1

Response to Comments on 

Implementation of the 2008 National

Ambient Air Quality Standards for

Ozone: State Implementation Plan

Requirements

February 13, 2015
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Table of Contents 

1.0 Introduction...................................................................................................................5

2.0 What are the SIP requirements for the 2008 ozone NAAQS?......................................10

A. What is the deadline for submitting nonattainment area SIP elements due under Clean 

Air Act (CAA or Act) section 182 for the 2008 ozone NAAQS? ................................10

1. Suggest consolidated SIP submittal at 36 months after designation.............10

2. Support consolidated SIP submittal due 30 months after designation..........11

3. Do not support consolidated SIP submittal...................................................12

4. Incorporate planning for the next ozone standard.........................................14

5. Marginal area RACT.....................................................................................15

6. RACT Implementation deadline ...................................................................16

7. Timely issuance of SIP guidance and rules ..................................................16

8. Multi-state nonattainment areas....................................................................17

B. What are the requirements for modeling and attainment demonstration SIPs? ...................18

1. Marginal areas...............................................................................................18

2. Moderate areas..............................................................................................19

3. Modeling guidance........................................................................................24

4. Capturing high emissions days in inventories ..............................................24

5. Modeled attainment test................................................................................35

6. Future years to model....................................................................................41

C. What are the RFP requirements for the 2008 ozone NAAQS?............................................44

1. 2008 ozone nonattainment areas for which no portion of the area has 

previously been required to meet the 15 percent RFP requirement 

for VOC ................................................................................................45

2. 2008 ozone nonattainment areas where portions have a previously 

approved 15 percent VOC reduction plan ............................................57

3. Non-creditable reduction calculations ..........................................................62

4. Alternative VOC-weighted RFP approach ...................................................64

5. Alternative Air quality approach ..................................................................68

6. Baseline year for RFP ...................................................................................73

7. Emissions outside the nonattainment area ....................................................85

D. How do RACT and RACM requirements apply for 2008 ozone NAAQS 

nonattainment areas?.....................................................................................................94

1. RACT SIP .....................................................................................................95

2. CTGs and ACTs............................................................................................97

3. RACT determinations.................................................................................101

4. Averaging over a nonattainment area .........................................................104

5. Trading within a nonattainment area ..........................................................105

6. Regional trading program ...........................................................................106

7. Consideration of the limited impact of VOC emissions in some areas ......110

8. MACT.........................................................................................................115

9. RACM in areas that are NOx-limited..........................................................116

E. Does the 2008 ozone NAAQS result in I/M programs?.....................................................117

1. Do not support check engine light proposal ...............................................117
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2. Alternative I/M programs ...........................................................................118

3. Substitute for I/M program .........................................................................120

4. Flexibility needed for future I/M programs................................................121

5. Onboard diagnostic (OBD) testing .............................................................122

6. Support acceleration simulation mode (ASM) testing................................123

7. Incorporation of Diesel Vehicles in I/M Program ......................................124

8. Funding for Vehicle Repair and Replacement Programs ...........................125

9. Separate rulemaking needed for I/M...........................................................126

10. Timing of I/M SIP.....................................................................................126

11. Oppose implementation of additional I/M programs................................127

F. How does transportation conformity apply to the 2008 ozone NAAQS? ..........................128

1. Requirements for VOC motor vehicle emissions budgets..........................128

2. Elimination of conformity requirements.....................................................128

3. Comment beyond the scope of the rulemaking...........................................133

G. What requirements for general conformity apply to the 2008 ozone NAAQS? ................133

1. Emission budgets for General Conformity should not be mandated ..........133

2. Support proposal to not make revisions to general conformity 

regulations...........................................................................................134

H. What are the requirements for contingency measures in the event of failure to meet a 

milestone or to attain?.................................................................................................134

1. 1 year’s worth of progress...........................................................................134

2. Reliance on already-adopted rules..............................................................135

3. Flexibility to use NOx or VOC measures....................................................137

4. Extreme nonattainment areas......................................................................138

5. Innovative measures....................................................................................140

I. How do the NSR requirements apply for the 2008 ozone NAAQS? ..................................140

1. General NSR requirements for the 2008 ozone NAAQS ...........................140

2. Offsets.........................................................................................................154

3. lnterpollutant Offset Substitution................................................................156

4. Economic Development Zones...................................................................161

5. SIP Submittal Date for Nonattainment NSR rules......................................162

J. What are the emission inventory and emission statement requirements? ...........................162

1. Emissions inventory....................................................................................162

2. Emissions statement requirements..............................................................166

K. What are the ambient monitoring requirements?...............................................................167

1. Cost of monitoring programs......................................................................167

2. Ambient monitoring rule.............................................................................167

L. How can an area qualify for a 1-year attainment deadline extension?...............................169

1. Support proposal .........................................................................................169

M. How will the EPA address transport of ozone and its precursors for rural 

nonattainment areas, multi-state nonattainment areas and international transport? ...169

1. Rural areas ..................................................................................................169

2. Methane as a Precursor...............................................................................170

3. International transport.................................................................................170

4. Interstate transport requirements.................................................................172
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N. How will the section 182(f) NOX provisions be handled?.................................................176

O. Emissions Reduction Benefits of Energy Efficiency/Renewable Energy Policies and 

Programs, Land Use Planning and Travel Efficiency.................................................176

1. Energy efficiency/renewable energy policies and programs ......................176

2. Land use planning.......................................................................................178

3. Travel efficiency . ......................................................................................179

P. Efforts to Encourage a Multi-Pollutant Approach When Developing 2008 Ozone SIPs...184

1. General support for a multi-pollutant approach..........................................184

2. Do not support a multi-pollutant approach .................................................185

Q. How does this proposed rule apply to tribes? ....................................................................185

1. VOC controls..............................................................................................188

2. Emission reduction credits..........................................................................189

3. NOx substitution..........................................................................................189

4. Areas with a previously submitted 15 percent VOC reduction plan ..........190

5. lnterpollutant Offset Substitution in the OTR.............................................190

S. Are there any additional requirements related to enforcement and compliance?...............191

T. What are the requirements for addressing emergency episodes? .......................................191

U. How does the ‘‘Clean Data Policy’’ apply to the 2008 ozone NAAQS? ..........................192

1. Support clean data policy............................................................................192

V. What assistance programs is the EPA considering for implementation of the 2008 

ozone NAAQS? ..........................................................................................................192

1. Ozone Advance...........................................................................................192

W. What is the deadline for states to submit SIP revisions to address the CAA section 

185 penalty fee provision for Severe and Extreme areas? ..........................................195

1. Support the proposed schedule ...................................................................195

X. Other Comments................................................................................................................195

1. Federal control measures ............................................................................195

2. Subpart 1 and Subpart 2..............................................................................197

3. Flexibility....................................................................................................202

3.0 What is the EPA proposing to address anti-backsliding issues related to 

transition from the 1997 ozone NAAQS to the 2008 ozone NAAQS?..................203

A. Revocation--general....................................................................................................203

B. Transition from the 1-Hour to the 1997 Ozone NAA.................................................203

C. Nonattainment NSR....................................................................................................203

D. Section 185 Fees.........................................................................................................203

E. Contingency Measures Requirement ..........................................................................203

F. What is the EPA proposing regarding anti-backsliding requirements for the 1-hour 

and 1997 ozone NAAQS?...........................................................................................203

G. Timing of 1997 Ozone NAAQS Revocation and Related Anti-Backsliding 

Requirements ..............................................................................................................203

1. Support revocation of the 1997 Ozone NAAQS.........................................203

2. Do not support revocation of the 1997 Ozone NAAQS .............................204

3. Comments regarding the date of revocation ...............................................206

4. Redesignation after revocation ...................................................................208

5. Continued attainment after revocation........................................................208
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H. What are the applicable requirements for anti-backsliding purposes following the 

revocation of the 1997 ozone NAAQS? .....................................................................209

1. General 209

2. New Source Review....................................................................................218

3. Section 185 fees..........................................................................................219

I. Application of Transition Requirements to Nonattainment and Attainment Areas....221

1. Requirements for Areas Designated Attainment for the 2008 Ozone 

NAAQS and Maintenance for the 1997 Ozone NAAQS....................222

2. Areas Designated Attainment for the 2008 Ozone NAAQS and 

Nonattainment for the 1997 Ozone NAAQS......................................226

3. Areas Designated Nonattainment for the 2008 Ozone NAAQS and 

Maintenance for the 1997 Ozone NAAQS .........................................228

5. Table 2 requirements--clarifications...........................................................230

J. Satisfaction of Anti-Backsliding Requirements for an Area ......................................230

1. Formal redesignation satisfies anti-backsliding requirements....................230

2. Redesignation Substitute satisfies anti-backsliding requirements..............233

1. General........................................................................................................239

2. Section 51.1118...........................................................................................240

L. What is the relationship between implementation of the 2008 ozone NAAQS and 

the CAA Title V permits program? ............................................................................240

1. Support for first approach for Title V permitting threshold .......................240

2. Support for the second approach for Title V permitting threshold.............241

4.0 Statutory and Executive Order Reviews.................................................................245

A. Environmental Justice.................................................................................................245

5.0 Other Comments.......................................................................................................247

A. General........................................................................................................................247

1. Improving the CAA ....................................................................................247

2. Most proposed rule elements are unnecessary............................................247

3. Menu of Control Measures .........................................................................247

B. Support for other commenters............................................................................................248

C. Codification error...............................................................................................................248

D. Los Angeles-South Coast Air Basin ..................................................................................248

2. Section 51.1118...........................................................................................240

L. What is the relationship between implementation of the 2008 ozone NAAQS and 

the CAA Title V permits program? ............................................................................240

1. Support for first approach for Title V permitting threshold .......................240

2. Support for the second approach for Title V permitting threshold.............241

4.0 Statutory and Executive Order Reviews.................................................................245

A. Environmental Justice.................................................................................................245

5.0 Other Comments.......................................................................................................247

A. General........................................................................................................................247

1. Improving the CAA ....................................................................................247

2. Most proposed rule elements are unnecessary............................................247

3. Menu of Control Measures .........................................................................247
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B. Support for other commenters............................................................................................248

C. Codification error...............................................................................................................248

D. Los Angeles-South Coast Air Basin ..................................................................................248

1.0 Introduction 

The Environmental Protection Agency (EPA) proposed a rule on June 6, 2013 (78 FR 34178), to 

facilitate implementing the 2008 ozone national ambient air quality standards (NAAQS) (the 

“2008 ozone NAAQS”) that were promulgated on March 12, 2008. This proposed rule addressed 

a range of state implementation plan (SIP) requirements for the 2008 ozone NAAQS, including 

requirements pertaining to attainment demonstrations, reasonable further progress (RFP), 

reasonably available control technology (RACT), reasonably available control measures 

(RACM), new source review (NSR) requirements in nonattainment areas, emission inventories 

and the timing of SIP submissions and of compliance with emission control measures in the SIP. 

Other issues also addressed in the proposed rule were the revocation of the 1997 ozone NAAQS 

and anti-backsliding requirements that would apply when the 1997 ozone NAAQS is revoked.

As noted in the proposal, the EPA will work closely with air agencies to provide assistance and 

flexibility in implementing the 2008 ozone NAAQS consistent with the implementation 

approaches that are adopted in the final implementation rule. 

Included in this document are summaries of the comments received on the proposed rule and the 

EPA’s responses. Comments are arranged consistent with the relevant sections of the proposed 

rule.

Table 1. Explanation of Acronyms and Frequently Used Abbreviations

Acronym Long Name

ACT Alternative Control Techniques 

CAA CAA

CFR Code of Federal Regulations

CSAPR Cross State Air Pollution Rule

CTG Control Techniques Guideline

EGU Electric Generating Units

EPA United States Environmental Protection Agency

FR Federal Register

HEDD High Electric Demand Days

MACT Maximum Achievable Control Technology

MATS Mercury and Air Toxics Standards

NAAQS National Ambient Air Quality Standards

NNSR Nonattainment New Source Review

NOx Nitrogen Oxides

NSPS New Source Performance Standards

NSR New Source Review
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PPB Parts per Billion

PSD Prevention of Significant Deterioration

RACM Reasonably Available Control Measures

RACT Reasonably Available Control Technology

RFP Reasonable Further Progress

SIP State Implementation Plan

TPY Tons per Year
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Table 2. List of Commenters and Associated Docket Numbers 

Docket Number Commenter Name

EPA-HQ-OAR-2010-0885-0119 J. Anderson

EPA-HQ-OAR-2010-0885-0122 Tauna M. Szymanski and Lucinda Minton Langworthy, 

Hunton & Williams LLP on behalf of the Utility Air 

Regulatory Group (UARG)

EPA-HQ-OAR-2010-0885-0127 Kipp A. Coddington, Environmental & Energy Counsel, 

American Automotive Leasing Association (AALA)

EPA-HQ-OAR-2010-0885-0128 Thomas Karol, Federal Affairs Counsel, National 

Association of Mutual Insurance Companies (NAMIC)

EPA-HQ-OAR-2010-0885-0129 Mathew Page, Vice President, Smith Aldridge, Inc.

EPA-HQ-OAR-2010-0885-0130 Michael G. Dowd, Director, Air Division, Virginia 

Department of Environmental Quality (DEQ)

EPA-HQ-OAR-2010-0885-0131 Kimberly A. Scarborough, Environmental Policy Manager 

- Air, PSEG Services Corporation

EPA-HQ-OAR-2010-0885-0132 Zak Covar, Executive Director, Texas Commission on 

Environmental Quality (TCEQ)

EPA-HQ-OAR-2010-0885-0136 Larry Greene, Executive Director/Air Pollution Control 

Officer, Sacramento Metropolitan Air Quality 

Management District (SMAQMD)

EPA-HQ-OAR-2010-0885-0137 Ronald W. Gore, Chief, Air Division, Alabama 

Department of Environmental Management (ADEM)

EPA-HQ-OAR-2010-0885-0138 Anonymous public comment

EPA-HQ-OAR-2010-0885-0139 Brad Poiriez, President, California Air Pollution Control 

Officers Association (CAPCOA)

EPA-HQ-OAR-2010-0885-0140 Pharr Andrews and Andrew Hoekzema, Co-Chair, Clean 

Air Coalition Advisory Committee (CACAC)

EPA-HQ-OAR-2010-0885-0141 John A. Paul, Administrator, Regional Air Pollution 

Control agency (RAPCA)

EPA-HQ-OAR-2010-0885-0142 Michael Bradley, Director, The Clean Energy Group

EPA-HQ-OAR-2010-0885-0143 E. Christopher Abruzzo, Acting Secretary, Pennsylvania 

Department of Environmental Protection (DEP)

EPA-HQ-OAR-2010-0885-0144 Jane Kozinski, Assistant Commissioner, Environmental 

Management, State of New Jersey

EPA-HQ-OAR-2010-0885-0145 Lorraine Krupa Gershman, Director, American Chemistry 

Council (ACC)

EPA-HQ-OAR-2010-0885-0146 Arthur N. Marin, Executive Director, Northeast States for 

Coordinated Air Use Management (NESCAUM)

EPA-HQ-OAR-2010-0885-0147 Seth Barna, Director, Chemical Products and Technology, 

American Chemistry Council (ACC)

EPA-HQ-OAR-2010-0885-0148 Michael Villegas, Air Pollution Control Officer, Ventura 

County Air Pollution Control District

EPA-HQ-OAR-2010-0885-0149 Hasan Ikhrata, Executive Director, Southern California 

Association of Governments (SCAG)
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EPA-HQ-OAR-2010-0885-0150 Barry R. Wallerstein, Executive Officer, South Coast Air 

Quality Management District (SCAQMD)

EPA-HQ-OAR-2010-0885-0151 Leslie Ritts, Counsel, National Environmental 

Development Association’s Clean Air Project 

(NEDA/CAP)

EPA-HQ-OAR-2010-0885-0152 Scott Nally, Director, Ohio Environmental Protection 

agency

EPA-HQ-OAR-2010-0885-0153 Keith Bentley, Chief, Air Protection Branch, 

Environmental Protection Division, Georgia Department 

of Natural Resources

EPA-HQ-OAR-2010-0885-0154 Todd Parfitt, Director, State of Wyoming Department of 

Environmental Quality

EPA-HQ-OAR-2010-0885-0155 George S. (Tad) Aburn and Lynn A. Liddington, CoChairs, Criteria Pollutants Committee, National 

Association of Clean Air Agencies (NACAA)

EPA-HQ-OAR-2010-0885-0156 Carlos Swonke, P.G., Director, Environmental Affairs 

Division, Texas Department of Transportation (TxDOT)

EPA-HQ-OAR-2010-0885-0157 George S. (Tad) Aburn, Director, Maryland Department of 

the Environment (MDE)

EPA-HQ-OAR-2010-0885-0158 Pamela F. Faggert, Vice President and Chief 

Environmental Officer, Dominion Resources Services, 

Inc.

EPA-HQ-OAR-2010-0885-0159 Tokesha M. Collins, Ken Miller LLP, Counsel for the 

Louisiana Chemical Association (LCA)

EPA-HQ-OAR-2010-0885-0160 Richard W. Corey, Executive Director, California Air 

Resources Board (CARB)

EPA-HQ-OAR-2010-0885-0161 Thure Cannon, President, Texas Pipeline Association 

(TPA)

EPA-HQ-OAR-2010-0885-0162 Lisa M. Jaeger, Counsel, Bracewell & Giuliani LLP, on 

behalf of the Council of Industrial Boiler Owners (CIBO)

EPA-HQ-OAR-2010-0885-0163 Joseph J. Martens, New York State Department of 

Environmental Conservation (NYSDEC)

EPA-HQ-OAR-2010-0885-0164 Michael Morris, Director of Transportation, North Central 

Texas Council of Governments (NCTCOG)

EPA-HQ-OAR-2010-0885-0165 Robert J. Morehouse and Shannon S. Broome, Points of 

Contact on behalf of The Air Permitting Forum

EPA-HQ-OAR-2010-0885-0166 Lucinda Minton Langworthy and Tauna M. Szymanski, 

Hunton & Williams LLP on behalf of the Utility Air 

Regulatory Group (UARG)

EPA-HQ-OAR-2010-0885-0167 J. Wick Havens, Interim Executive Director, Ozone 

Transport Commission (OTC)

EPA-HQ-OAR-2010-0885-0168 Ali Mirzakhalili, P.E., Director, State of Delaware 

Department of Natural Resources & Environmental 

Control, Division of Air Quality
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EPA-HQ-OAR-2010-0885-0169 Myra C. Reece, Chief, Bureau of Air Quality, South 

Carolina Department of Health and Environmental Control 

(SCDHEC)

EPA-HQ-OAR-2010-0885-0170 Peter Zalzal and Graham McCahan, Environmental 

Defense Fund (EDF)

EPA-HQ-OAR-2010-0885-0171 Zachary L. Craft, Baker Botts, LLP, on behalf of The 8-

Hour Ozone SIP Coalition (identical to comment 0173)

EPA-HQ-OAR-2010-0885-0172 John S. Lyons, Director, Kentucky Division for Air 

Quality, Energy and Environment Cabinet, Kentucky 

Department of Environmental Protection

EPA-HQ-OAR-2010-0885-0173 Zachary L. Craft, Baker Botts LLP on behalf of BCCA 

Appeal Group (BCCA)

EPA-HQ-OAR-2010-0885-0174 Michael O. Lebeis, Senior Environmental Engineer, 

Environmental Management and Resources, DTE Energy

EPA-HQ-OAR-2010-0885-0175 Bart Sponseller, Director, Bureau of Air Management, 

Wisconsin Department of Natural Resources (WDNR)

EPA-HQ-OAR-2010-0885-0176 J. Dillard

EPA-HQ-OAR-2010-0885-0177 Connecticut Department of Energy and Environmental 

Protection (DEEP)

EPA-HQ-OAR-2010-0885-0178 Kyra L. Moore, Director, Missouri Department of Natural 

Resources (DNR)

EPA-HQ-OAR-2010-0885-0179 Sheila C. Holman, Director, North Carolina Division of 

Air Quality (NCDENR)

EPA-HQ-OAR-2010-0885-0180 Earthjustice et al.

EPA-HQ-OAR-2010-0885-0181 Mark Macarro, Tribal Chairman, Pechanga Indian 

Reservation
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2.0 What are the SIP requirements for the 2008 ozone NAAQS?

A. What is the deadline for submitting nonattainment area SIP elements due under Clean Air 

Act (CAA or Act) section 182 for the 2008 ozone NAAQS?

1. Suggest consolidated SIP submittal at 36 months after designation

Comment: Commenters (0130, 0132, 0137, 0156 and 0175) supported the flexibility offered by 

a consolidated approach and stated the deadline for such a submittal should be 36 months 

following the effective date of designations. Commenters suggested, the timeline for the 

combined submittal be at the maximum statutory timeline for the attainment plan, in the case of 

Moderate nonattainment areas 36 months from designation. 

Commenter (0130) stated that, RACT determinations are highly contentious, facility-specific 

control determinations involving negotiation of control requirements and which must be SIP 

revisions with public notice requirements. The Commenter (0130) stated that, the deadline of 24 

months from designation is impossible to meet and 30 months would be difficult as well. The 

Commenter (0130) stated that, RFP plans are difficult to create and finalize in 36 months and 

attainment plans, with modelling demonstrations, are significant efforts that need every bit of 36 

months for proper development. 

Commenter (0132) stated that, the EPA does not provide a rationale for why 30 months provides 

for a de minimis delay, but 36 months does not. The Commenter (0132) stated that, submitting 

the attainment demonstration to the EPA in 30 months, instead of 36 months, would not advance 

attainment of the standard because the EPA's implementation deadlines for RACT, RACM and 

RFP control measures are independent of the SIP submittal date. Commenter (0132) stated that, 

the delayed release and finalization of the implementation rule and revised modeling guidance 

warrant a 36-month deadline given the length of time needed to have stakeholder meetings, 

proposal and adoption of the SIP and rule revisions. 

Commenter (0156) supported the consolidated approach because it would streamline 

administrative processing, increase meaningful public involvement, and it should also reduce the 

number of conformity determinations required by SIP actions (e.g. within 24 months of a new 

budget or a SIP revision). 

Commenter (0137) supported the EPA's proposal to align deadlines for the attainment SIP and 

any required new inspection and maintenance program (I/M) SIP so that both are due at the time 

the attainment SIP is due. 
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Response: Although we proposed a consolidated approach for the state’s choice to consolidate 

SIP submittal requirements for their respective areas into a SIP due at 30 months after 

designation, we are not finalizing that approach given the uncertainty regarding the statutory 

basis for providing such flexibility. Rather, the EPA is finalizing the approach that the various 

SIP elements are due based on the timeframes provided in CAA section 182.

The final rule requires all areas to submit the various elements of the SIP in the period of time 

provided by the statute. The time period specified in section 182 for the emission inventories and 

RACT SIPs is 2 years, 3 years for 15 percent RFP plans and Moderate area attainment 

demonstrations, and 4 years for 3 percent per year RFP plans and attainment demonstrations 

from Serious and higher areas. The specified time period for states to submit each required 

element will run from the effective date of an area’s nonattainment designation for the 2008 

ozone NAAQS.

2. Support consolidated SIP submittal due 30 months after designation

Comment: Commenters (0139, 0143, 0144, 0146, 0150, 0152, 0154, 0155, 0157, 0158, 0160, 

0166, 0169, 0172, 0177 and 0179) generally supported the EPA’s flexible approach.

Commenters (0143, 0146, 0150, 0154, 0155, 0157, 0166 and 0177) supported this flexibility if 

the EPA is able to establish a firm legal basis before finalizing the proposed rule and requested 

that the EPA carefully explain the policy and legal basis for these options in the final rule, to 

avoid the uncertainty of litigation. 

Commenter (0152) generally supported the EPA’s attempts to incorporate more flexible 

approaches but believed the proposal falls short of the flexibility needed to implement the CAA 

effectively—for example, the alignment of the attainment demonstration SIP with the emission 

inventory and RACT SIPs due earlier.

Commenter (0177) stated, the 30-month option provides a more realistic timeframe for 

completion of inventories and adoption of any new RACT regulations and added that, if this 

flexibility is included in the final rule, the EPA should make it clear that any associated RACT, 

RACM or other control measures must be implemented according to mandated CAA deadlines 

to ensure expeditious attainment. 

Commenter (0179) indicated a preference for the second option because it allows states to 

undertake a less burdensome planning process, including having one period for public review 

and opportunity for public hearing for all the SIP elements involved. Commenter (0179) added 

that, states should be given sufficient time to adopt rules in the event the EPA issues updates to 

Control Techniques Guidelines (CTG) or Alternative CTG. 

Commenters (0158 and 0166) supported giving states the option to follow the statutory deadlines 

or to submit a consolidated SIP within 30 months, but stated the EPA should make clear in the 

final rule that it is not requiring states to submit consolidated SIPs within 30 months since such a 
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requirement would be contrary to the Act, which provides for later deadlines for certain SIP 

elements. 

Commenter (0166) supported the EPA’s proposal allowing the use of existing, already-prepared 

inventories and previously established schedules.

Response: The EPA appreciates the support of the Commenters. However, we are not including 

the consolidated approach in the final rule. We proposed the consolidated approach to provide 

flexibility to states in order to balance such flexibility with what the CAA specifically requires. 

Several Commenters questioned the legal basis for providing such flexibility in the consolidated 

approach (See section below for details). The EPA agrees and is not providing the consolidated 

approach in the final rule. The final rule requires all areas to submit the various elements of the 

SIP within the period of time provided by the statute. 

3. Do not support consolidated SIP submittal 

Comment: Keep the SIP submission schedule consistent with the CAA

Commenters (0151, 0159, 0163 and 0168) stated their preference is to adhere to the period of 

time provided by the statute. Commenter (0151) expressed concerns regarding the use of 

modeling efforts under the Cross State Air Pollution Rule (CSAPR) and stated that it may make 

better sense for local authorities to stick to the established SIP submittal schedule and examine 

closely the emission inventory baseline before deciding which actions must be taken in the 

overall SIP strategy for attainment and then providing time to model those results. Commenter 

(0151) suggested accepting the fact that states could be late on their first 2008 SIP inventory 

submissions and keeping to the normal SIP submission schedule. 

Commenters (0151 and 0163) questioned the viability of the “state's choice” alternative because 

the required SIP elements create a significant workload that may be difficult for states to 

complete within 30 months. 

Commenter (0151) noted that, one of the dates that must be met sooner rather than later is not 

even discussed in the proposal— for states to adopt/make nonattainment NSR (NNSR) 

applicable in expanded nonattainment areas or adopt NNSR requirements within 18 months, as 

required by the D.C. Circuit in NRDC v. EPA (Phase 2 Ozone Plan). 

Commenter (0168) concluded that, this alternative should not be adopted because it is providing 

flexibility that is inconsistent with the CAA, inconsistent with prior rules and is not needed given 

the EPA’s classification scheme. Commenter (0168) stated that, the proposal would impact only 

areas classified as Moderate and higher, and given that most areas are classified as Marginal, it 

would have little utility. Further, the Commenter noted that, those states with areas currently 

classified as Moderate and above already have significant experience preparing emission 

inventories and have been through at least one round of RACT SIPs. 

Commenter (0180) stated, the EPA may not extend the deadlines because the proposed 

extensions would unlawfully rewrite the statute and be arbitrary. Commenter (0180) stated, the 
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EPA’s policy arguments cannot override Congress’s intent and cited NRDC v. EPA, 489 F.3d 

1364, 1373-74 (D.C. Cir. 2007). Commenter (0180) disagreed that, the 6-month delay is “de 

minimis” and argued that when Congress establishes an explicit submittal deadline, the EPA 

lacks authority to override it and cited Sierra Club v. EPA, 705 F.3d 458, 467-69 (D.C. Cir. 

2013) and Pub. Citizen v. FTC, 869 F.2d 1541, 1557 (D.C. Cir. 1989). Commenter (0180), citing 

SCAQMD, 472 F.3d at 886-88, 894-95, stated, Congress amended the Act to limit the EPA’s 

discretion and to expedite attainment of the NAAQS, thus the delay is thus contrary to 

Congress’s intent. Commenter (0180) stated that, because the proposal breaks the law to achieve 

an end that could be lawfully achieved and is irrational and arbitrary. Commenter (0180) also 

stated that, the text of § 51.1115 should reflect the preamble statement which indicated the 

preferred alternative would only be available for Moderate and higher areas. 

Response: After considering comments questioning the legal supportability of the consolidated 

approach, the EPA has concluded that we do not have a sufficient statutory basis to provide this 

flexibility. Therefore, the final rule includes only the option of submitting SIP elements on their 

statutory deadlines, as this approach is the one that is most clearly supported by the CAA. 

Additionally, we note that there is no need to modify § 51.1115 as suggested by the Commenter 

because we are not finalizing the consolidated approach.

Comment: Use the actual date of designation

Commenter (0180) contended that to be consistent with the Clean Air Act (CAA), the trigger 

date for the submission obligations must be when the designations are made, not some later 

“effective date” the EPA arbitrarily assigns. Commenter (0180) claims the proposed extensions 

would unlawfully rewrite the statute and be arbitrary if the trigger dates are based on the 

“effective date” of designations as the trigger for the nonattainment SIP submission obligations 

instead of the signature date by the EPA administrator for the 2008 ozone nonattainment 

designation action. Commenter (0180) argued that, the submission obligations originally ran 

from date of enactment of the 1990 Clean Air Act Amendments – November 15, 1990. 

Response: We disagree with the Commenter that the CAA mandates the SIP submittal due dates 

in subpart 2 must run from the date the designations are signed instead of from the effective date 

of designations and classifications. As an initial matter, the SIP deadlines in subpart 2 for the 1-

hour ozone standards, as set forth in section 182, are established as a specified period of time 

(months or years) from November 15, 1990, the date of enactment of the CAA Amendments of 

1990, and also generally the date it became effective. The EPA notes that the SIP deadlines for 

areas initially designated nonattainment for new/revised 8-hour standards are not directly 

addressed by the CAA. Instead, EPA logically refers to section 181(b)(1), which addresses new 

nonattainment designations for the 1-hour standards, to derive reasonable deadlines for SIP 

obligations associated with designations and classifications under the new/revised 8-hour 

standards. Section 181(b)(1) indicates that “...any absolute, fixed date applicable in connection 

with any such requirement is extended by operation of law by a period equal to the length of time 

between November 15, 1990, and the date the area is classified. We believe that provision can be 

reasonably interpreted to mean the effective date of the designation and classification, and we 

have historically interpreted it as such for ozone-related SIP obligations and attainment 

deadlines, and also similarly for other pollutants. See, 40 Code of Federal Regulation (CFR) 
14

51.902, Table 1 (specifying that the attainment periods in the Table for the 1997 8-hour ozone 

NAAQS are “years after the effective date of nonattainment designation”) 

After the comments were submitted, the D.C. Circuit has confirmed that the better reading of the 

CAA is that the clock for determining when attainment is due begins when an area’s designation 

becomes effective, not at some later time. NRDC v. EPA, D.C. Cir. No. 12-1321 (Dec. 23, 

2014). To provide clarity to states after the D.C. Circuit court decision, the EPA is modifying 40 

CFR 51.1103 consistent with that decision to establish attainment dates that run from the 

effective date of designation, i.e., July 20, 2012.

1 This is the same approach the EPA used in 

past ozone implementation rules and the approach the court indicated was consistent with 

Congressional intent.

2 The maximum attainment dates for nonattainment areas in each 

classification under the 2008 NAAQS based on the July 20, 2012 effective date are as follows: 

Marginal - 3 years from effective date of designation; Moderate - 6 years from effective date of 

designation; Serious - 9 years from effective date of designation; Severe - 15 years (or 17 years) 

from effective date of designation; and Extreme - 20 years from effective date of designation. 

4. Incorporate planning for the next ozone standard

Comment: Commenter (0151) suggested, the agency should re-propose this portion of the SIP 

Requirements Rule and “key” the 2008 NAAQS SIP to planning for the next ozone NAAQS. 

Commenter (0151) stated that, one alternative might be to actively anticipate that the EPA will 

 

1 We are finalizing this approach without additional notice-and-comment. As noted, we took 

comment in the original proposal on two approaches: the option we promulgated and which the 

court rejected, and the option we are promulgating here. Moreover, the court decision strongly 

indicates that the approach we are promulgating here is the only approach that is consistent with 

Congressional intent. In light of the need for certainty for the states and regulated parties, the fact 

that we previously solicited comment on the approach we are adopting here, and the limited 

discretion the court believes EPA has been provided under the Act, we believe additional 

comment is unnecessary and contrary to the public interest. 

2 We note that during the comment period on the May 2012 rule establishing the attainment 

dates, a few commenters claimed that the attainment period should run from the time the 

designations actions were signed by the Administrator rather than the effective date of 

designation. In the final May 2012 rule, we responded to this comment explaining why we 

believed the arguments the commenters raised were not supported by the statute. Regardless we 

note that whether the attainment date runs from the date of signature or the effective date of 

designation, the attainment year will be the same, as an attainment showing is based on the most 

recent three full years of ozone data available. Thus, for example, under either approach, the 

relevant years for demonstrating attainment for a Marginal area will be 2012-2014 and for a 

Moderate area, 2015-2017. 
15

need to make a deficiency finding on the first half of states’ SIP planning obligations and issue a 

generic SIP call (as it has done in the past for other NAAQS), which would provide at least 18 

months and possibly additional time for preparation of the 2014 emission inventory, RACT and 

infrastructure SIP, allowing additional time for ozone planning to catch up with the new 

standard. Commenter (0151) stated that, this 2008 NAAQS SIP Requirement Rule is an 

important link to achieving the anticipated revised ozone NAAQS and should be viewed in that 

context. Commenter (0151) suggested that, in finalizing this rulemaking the EPA should 

endeavor to minimize duplicative state legacy ozone SIP planning requirements for both the 

1997 and 2008 NAAQS. 

Commenter (0151) stated that, it would be reasonable to conclude that Congress meant only to 

apply 182(b) as minimum requirements to the SIP planning cycle immediately following the 

1990 CAA Amendments and thereafter, presumed that states would resume SIP planning under 

Title 1 Subpart 1, consistent with the Court’s determination in South Coast, supra, that section 

172(e) in Title 1 serves as the backstop against backsliding. Applying this legal theory, 

Commenter (0151) stated, allows the EPA to suspend multiple SIP-planning efforts for former 

ozone standards, concentrating on attainment of the most recent NAAQS, dispensing obsolete 

elements like RVP or all- volatile organic compounds (VOC) RFP and allowing states to tailor 

RFP planning without layering on multiple requirements that have no meaning except to penalize 

states and business.

Commenter (0169) stated, the shortened timeframe between finalizing the 2008 ozone NAAQS 

implementation rule and the expected proposal of a revised ozone NAAQS provides the EPA 

with an excellent opportunity to implement a co-proposal process. Commenter (0169) stated that, 

this is the perfect opportunity for the EPA to utilize many of the "lessons learned" from the 

Full/Life Cycle Analysis Project (FCAP/LCAP) which began during the 2012 PM2.5 NAAQS 

proposal process. 

Response: The EPA has not promulgated a revision to the 2008 NAAQS and designations for 

that standard would occur 2 (and up to 3) years following promulgation of any NAAQS revision. 

SIPs for any such revised standard would not be due until well after SIPs are required to be 

submitted for the 2008 ozone NAAQS. For this reason EPA believes it is premature, impractical, 

and not legally supported by the CAA to further delay planning obligations for the 2008 standard

in order to consider obligations associated with a future, yet to be determined standard.

5. Marginal area RACT

Comment: Commenter (0180) stated that, because the EPA has (correctly) determined that 

implementation of the 2008 standard is governed by subpart 2, the rule must require states to 

submit, within 6 months of designation, the RACT provisions required for Marginal areas under 

42 U.S.C. § 7511a(a)(2)(A). Commenter (0180) stated, the EPA’s proposed RACT 

implementation deadline also does not assure consistency with the statute with respect to areas 

that are designated nonattainment for the 2008 standard in the future. Commenter (0180) stated 

that, to be consistent with the Act and prior EPA rules and policy, RACT controls for Marginal 

areas must be implemented before the start of the ozone season in the year in which the 

attainment deadline falls. 
16

Response: The EPA disagrees with the comment that states must submit RACT corrections or 

additions for Marginal areas within 6 months of designation for the 2008 ozone NAAQS. The 

EPA clarifies that the obligations under §182(a)(2)(A) section apply only to nonattainment areas 

designated before 1990. The 2008 ozone NAAQS implementation rule takes the same position as 

the 1997 ozone implementation rule for the application of the RACT “fix-up” obligations under 

§182(a)(2)(A). The 1997 ozone implementation rule took the position that §182(a)(2)(A) only 

applies to pre-1990 nonattainment areas. The RACT fix-up provision under §182(a)(2)(A) for a 

nonattainment area classified as Marginal under the 2008 ozone NAAQS would only apply to 

those areas for which the EPA issued a RACT SIP Call before the 1990 CAA Amendments. 

6. RACT Implementation deadline

Comment: Commenter (0180) stated, the proposed implementation deadline is unlawful and 

arbitrary as to the RACT requirements in section 182(a)(2)(A) for Marginal areas, as it would 

post-date the attainment deadline for such areas by more than 2 years.

Response: The EPA agrees with the comment that implementation deadline of 54 1⁄2 months

applies to states required to implement RACT for areas designated nonattainment for the 2008 

NAAQS. The EPA does not agree that RACT is required for the designated nonattainment areas 

classified as Marginal.

Comment: Commenter (0180) believed that the EPA must rephrase the outside implementation 

deadline for RACT for sources covered by section 182(b)(2)(B) and (C) as 54 1⁄2 months after the 

date of nonattainment designation for the 2008 standard.

Response: The EPA agrees with the comment that RACT rules should be implemented by the 

respective state within 54 1⁄2 months after the date of nonattainment designation for the 2008 

standard.

7. Timely issuance of SIP guidance and rules

Comment: Commenters (0139, 0150, 0153, 0155, 0157, 0163, 0169, 0175 and 0178) requested 

that the EPA issue guidance necessary for nonattainment areas to complete their SIP submittals 

on a timely basis. 

Commenter (0139) stated that, states need to know what they are required to do as they prepare 

their SIP submissions. Commenter (0163) urged the EPA to update outdated guidance (e.g., 

RACT, Emissions Inventory) that states use in preparing their SIPs; most of these documents 

were prepared two decades ago to address the 1-hour ozone standard and are inadequate for the 

2008 ozone NAAQS. Commenter (0150) stated, it is important to identify the test method in the 

rule, so that industry will know how compliance will be measured and for the EPA to include 

SIP implementation guidance as quickly as possible, so that states will know how the adequacy 

of their SIP revisions will be measured. Commenter (0169) stated, it is difficult to have 

meaningful public participation when the state cannot address stakeholder and community 

questions because the EPA has not finalized guidance and other requirements necessary to 
17

implement the standards. Commenter (0175) stated that, states may be unable to meet the CAA 

deadlines if these rules are not issued in a timely manner.

Commenter (0130) stated that, in areas where reductions in VOC ozone precursors are shown to 

have minimal effects on ozone air quality, the EPA should update its redesignation request and 

maintenance plan guidance to reflect this science. Commenter (0130) added that, states also need 

other types of guidance on the analysis and regulation of High Electric Demand Days (HEDD) 

units, including RACT analyses and other types of controls which generally are not cost effective 

given current guidance on the calculations of cost/ton metrics. 

Commenters (0139, 0141, 0150, 0153, 0155, 0157, 0169 and 0175) stated that, SIP guidance 

should be proposed and finalized on the same time schedule as the proposal and finalization of 

the standard itself. If the EPA is not able to simultaneously release both a NAAQS and the 

implementation rule (proposed and final), Commenter (0169) suggested that, the effective date 

for the standard should be delayed until the implementation rule is finalized.

Commenter (0154) implored the EPA to propose implementation guidelines when the EPA 

finalizes an NAAQS. Commenter (0154) stated that, failure on the EPA's part to issue timely 

rules, sets the states up for failure, invites lawsuits by frustrated interest groups and leads us all 

down a path where we spend most of our time fighting over missed deadlines, rather than 

focusing on environmental protection. Commenter (0139) requested the EPA’s prompt action on 

SIP submittals that have already been received.

Response: The EPA issues NAAQS implementation guidance to aid air agencies in efficiently 

meeting their CAA obligations even though the Act does not mandate the EPA to issue such 

guidance (with a few exceptions). The EPA strives to issue these guidance and rules with clarity 

and in a timely manner, as we understand the challenges that states face in implementing actions 

to meet the intent of the statute. To improve our performance in this regard, over the past year, a 

joint EPA-state work group has been focusing on the timing of issuing guidance needed for 

states to meet their NAAQS implementation CAA deadlines. The work group’s efforts have led 

to the development of an optimal schedule for the EPA to target for developing and issuing any 

implementation guidance and rules, as necessary, which the EPA intends to follow. 

8. Multi-state nonattainment areas

Comment: Commenter (0159) supported the EPA’s interpretation of the requirements for multistate nonattainment areas, noting that it would be patently unfair for a cooperative and fully 

engaged state to be penalized for the actions, or lack thereof, of another state that is part of the 

same multi-state nonattainment area. 

Commenter (0169) did not support the EPA’s proposal that multi-state nonattainment areas adopt 

the same SIP submittal deadline and viewed this as impractical in light of South Carolina's past 

experience with the York County 1997 ozone nonattainment area (York County area) which is 

part of the Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina (Metrolina) 

nonattainment area. Commenter (0169) stated that, states often have differing regulatory 

processes and legislative timeframes, which make SIP submittal deadlines impossible to 
18

coordinate across state lines.

Response: These comments were made in response to the EPA’s proposed option to allow states 

to choose between the statutory SIP due dates or a consolidated approach with all SIP 

requirements due at 30 months from the designation effective date. The proposed option would 

have allowed the states the option to choose between the statutory or consolidated SIP due dates. 

The EPA proposal required states in a multi-state area to choose the same SIP due date option. 

The EPA is finalizing the approach requiring that all SIPs are due according to the statutory 

deadlines. We believe since the consolidated approach is not being finalized then the 

Commenter’s concern is not an issue with the states not having a choice between different SIP 

due date schedules because all states in the multi-state area will be on the same statutory SIP due 

date schedule.

B. What are the requirements for modeling and attainment demonstration SIPs?

1. Marginal areas

Comment: Support proposal

Commenter (0163) stated, they agreed with the EPA’s proposal and had requested a 

reclassification to Moderate based on a demonstration (with modeling) that the New York City 

metropolitan area is unlikely to attain the 2008 ozone NAAQS by the Marginal attainment 

deadline. 

Response: Under the CAA section 181(b)(3) states are able to request a voluntary 

reclassification to a higher level. However, in this scenario, the state requesting a voluntary 

reclassification is one of several states in a multi-state nonattainment area. In line with CAA

§182(j)(1) addressing multi-state nonattainment areas, the EPA believes that the states should 

behave in a coordinated manner when working toward attainment. For the EPA to honor any 

request for a reclassification of a multi-state area, the EPA has interpreted §182(j)(1) to require 

all states that are part of a multi-state nonattainment area to support the request.

Comment: CSAPR Model

Commenter (0159) agreed with the EPA's position that Marginal areas should implement such 

controls as needed to get the necessary emissions reductions to meet the 2008 ozone NAAQS 

within 3 years, but did not support the EPA's recommendation that such areas use the CSAPR 

model to examine whether they will timely attain the 2008 standard. 

Response: The EPA recommended that states with Marginal areas look at available information 

(including modeling) to help determine if the area is likely to attain the NAAQS within 3 years. 

This was a recommendation and imposed no modeling or attainment demonstration requirements 

on Marginal nonattainment areas. The EPA is not “promoting” the use of the CSAPR modeling 

or any other specific technical information. We simply listed the CSAPR modeling as possibly 

providing useful information to the states. That may or may not be the case for any particular 

Marginal nonattainment area. There may be other information, including more recent modeling 

analyses that are more relevant to a particular area. Regardless, states with Marginal areas are not 
19

obligated to submit an attainment demonstration or complete a modeling analysis for these areas.

Comment: Bump-up concern

Commenter (0169) questioned both how to prove to the EPA that York County has attained the 

2008 ozone NAAQS and how to defend the area against a mandatory "bump-up" despite the SIP 

Requirements Rule suggestion that states "use available modeling information to examine the 

likelihood of whether a Marginal area would attain within 3 years." Similarly, given the current 

status of the CSAPR per the DC Circuit Court's opinion in EME Homer City Generation v. EPA

(DC Cir. 2012), Commenter (0169) considered it largely inappropriate for the EPA to suggest 

states rely on modeling from the CSAPR and to assume that states have the ability to model as 

suggested in the rule. Commenter (0169) added that, in the letter denying the Department's 

request for reconsideration of the 2008 ozone NAAQS designation for York County, Lisa P. 

Jackson (former EPA Administrator) stated, "York County is properly designated nonattainment 

because of its contribution to ozone nonattainment in the Charlotte, N.C.-Rock Hill, S.C., area." 

Response: The EPA is not promoting the use of the CSAPR modeling. Rather, we simply listed 

the CSAPR modeling as possibly providing useful information to the states. That may or may not 

be the case for any particular Marginal nonattainment area. There may be other data, including 

more recent modeling analyses that are more relevant to a particular area. But either way, states 

with Marginal areas are not obligated to submit an attainment demonstration or complete a 

modeling analysis for these areas. Regarding the issue pertaining to York County, the County is 

part of a multi-state nonattainment area. In line with CAA §182(j)(1) addressing multi-state 

nonattainment areas, the EPA believes that the states should behave in a coordinated manner 

when working toward attainment. 

2. Moderate areas

Comment: The EPA exceeded its authority

Commenters (0151 and 0173) stated that, the EPA exceeded its authority to require states to 

utilize photochemical grid modeling for 2008 ozone SIP demonstrations. 

Commenter (0173) added that, for the EPA to require photochemical modeling for Moderate 

nonattainment areas undermines states' discretion under the statute. Commenter (0173) asserted 

that, Courts have routinely noted that states have broad discretion in fashioning their control 

strategies where the CAA does not make a specific prescription (citing Union Elec. Co. v. EPA, 

427 U.S. 246 (1976); and Train v. NRDC, 421 U.S. 60 (1975). Commenter (0173) stated, the 

EPA's authority to prescribe requirements for Moderate nonattainment area SIPs is restricted to 

that which is specified by the CAA, which does not include photochemical modeling.

Commenter (0173) also opposed the proposed expansion of photochemical modeling 

requirements because it would worsen existing bottlenecks in the SIP development and approval 

process. Commenter (0173) asserted, the EPA should not require more areas to submit modeled 

attainment demonstrations where the EPA cannot keep up with the existing rate of SIP 

submissions. 
20

Response: The EPA disagrees with the Commenters and believes that EPA has the authority to 

require states to use appropriate modeling to predict the effect of emissions on air quality of any 

NAAQS, as we did for the 1997 ozone NAAQS. States are required to submit an attainment 

demonstration for Moderate areas. Since photochemical modeling is the most scientifically 

rigorous technique to determine NOx and/or VOC emissions reductions needed to show 

attainment of the NAAQS, we are requiring photochemical modeling for all attainment 

demonstrations, including those for Moderate areas. However, in concert with the flexibility 

applicable to Serious and above areas under section 182(c)(2)(A), EPA will consider on a caseby-case basis other analytical methods that are at least as effective as photochemical modeling.

The CAA section 182(c)(2)(A) requires Serious nonattainment areas to submit an attainment 

demonstration which includes photochemical modeling or any other analytical method 

determined by the Administrator to be at least as effective. Section 182(j)(1)(B) also requires 

multi-state nonattainment areas to use photochemical grid modeling (or any other analytical 

method determined by the Administrator to be at least as effective) for their SIPs. Since 182(j) 

applies to all nonattainment areas, not just Serious and above, we have interpreted this provision 

to also apply to multi-state Moderate nonattainment areas.3

The specific authority to require photochemical modeling for Moderate nonattainment areas is 

derived from section 110(A)(2)(k) which gives the Administrator the authority to require air 

quality modeling for the purpose of predicting the effect on ambient air quality of emissions of 

any air pollutant for which there is an established NAAQS. Here, the EPA is requiring states to 

use photochemical modeling to predict the amounts of NOx and/or VOC reductions that are 

needed to show that the area will attain the ozone NAAQS. Since the EPA has the legal authority 

to require photochemical modeling, and there is no technical reason to differentiate between the 

rigor of the attainment demonstration for all Moderate and above areas, the EPA continues to 

believe that it is appropriate to require an attainment demonstration based on photochemical 

modeling (or any other analytical method determined by the Administrator to be at least as 

effective) for all Moderate areas. 

Comment: State discretion

Commenter (0152) stated that, modeling should be left at the state's discretion because the state 

is in the best position to determine if, and when, a more in-depth analysis than required by statute 

may be necessary and it should not be mandated by the EPA in all instances.

Response: The EPA believes that a minimum requirement for all Moderate and above 

nonattainment areas is to submit an attainment demonstration that is based on photochemical 

modeling or any other analytical method determined by the Administrator to be at least as 

 

3 The photochemical grid modeling requirement does not apply to multi-state Marginal areas 

because Marginal areas are not required to submit an attainment demonstration.
21

effective. Although photochemical modeling is the most scientifically rigorous technique to 

determine NOx and/or VOC emissions reductions needed to show attainment of the NAAQS, 

states still have discretion to propose to EPA other techniques that would fulfill the attainment 

demonstration obligation. Since states need EPA approval of alternative analytical methods, they 

should work closely with the EPA to determine the most appropriate option(s) for the attainment 

demonstration. 

Comment: Rural wintertime exemption

Commenter (0154) stated that, there are now a number of rural areas in the country with 

wintertime ozone attainment issues and recommended that the EPA exempt rural wintertime 

ozone nonattainment areas from the photochemical modeling requirement for the same reason—

that a wintertime PGM or proven alternative analytical method has not been developed. 

Commenter (0154) stated, the EPA clearly has a lead responsibility to develop and test models 

that can be used consistently across the nation.

Response: The EPA recognizes that the causes of rural wintertime ozone exceedances are 

different than typical summer exceedances. However, the CAA does not distinguish between 

summer and winter ozone areas. Areas with wintertime violations are designated as 

nonattainment based on the same classification tables as all other nonattainment areas. They 

therefore must meet all of the appropriate CAA requirements for their particular nonattainment 

classification. 

Nonattainment areas classified as Moderate and above, even those that may experience 

wintertime ozone problems, are required to submit an attainment demonstration. However there 

is flexibility in determining analytical methods to be used in developing the demonstration. The 

EPA will consider the nature of the ozone problem in reviewing available models and potential 

alternative methods for demonstrating attainment. There is also ongoing research which has 

successfully identified model science enhancements which have improved photochemical model

performance in wintertime ozone situations. Some of these science updates may be available for 

states to use in their attainment demonstrations by the time modeling is needed for areas with 

wintertime ozone problems.

Comment: Alternatives to photochemical modeling

Commenters (0173, 0175 and 0179) requested that, the EPA support states in using alternatives 

to photochemical grid modeling for their attainment demonstrations. 

Commenter (0175) stated that, while photochemical modeling is an important and long-used tool 

for ozone SIP planning, it also has key limitations. For example, Commenter (0175) claimed 

modeling relies heavily on limited spatial and temporal information on emissions and 

meteorology and often cannot be precisely calibrated to reflect measured air quality data and that 

some control strategy elements may be difficult to assign to emissions at a distinct point and 

time. Commenter (0175) stated that, an example of a successful SIP that relied on an alternative 

to photochemical modeling was the Houston area's SIP, approved by the EPA in 2006, which 

demonstrated that a photochemical model could not replicate the events involving rapidly formed 
22

ozone that then drove the area's design value. Commenter (0175) stated, the Houston SIP relied 

in part on photochemical modeling, but also included assessments of ambient monitoring data, 

aircraft studies and other tools to support a change from the previous control strategy, including a 

tailored strategy to reduce emissions of selected highly-reactive VOC species by approximately 

36 percent. See TCEQ, Post-1999 Rate-of-Progress and Attainment Demonstration Follow-Up 

SIP for the Houston/Galveston Ozone Nonattainment Area (Rule Log No. 2002w046a-SIP-AI) 

(Dec. 13, 2002). 

Response: The EPA agrees that additional information, including alternative techniques, could 

be used to help demonstrate that an area will attain the NAAQS. Photochemical modeling is the 

most technically credible tool to estimate emissions reductions needed to show attainment. 

However, other tools, such as ambient data and emissions analyses can be used to supplement 

modeling. In addition, as the Commenter notes, modeling conducted by other groups, including 

multi-jurisdictional organizations and the EPA, can be used as part of the attainment 

demonstration. 

In some cases, regional or national photochemical modeling may be sufficient to serve as the 

modeling analysis for the attainment demonstration. In that case, the EPA could consider 

appropriate regional or national scale photochemical modeling as having satisfied the 

“photochemical modeling” requirement for Moderate and above areas. Photochemical modeling 

conducted by a third party needs to be well documented and shown to be appropriate for the area. 

But since it is photochemical modeling, it would not need to be approved as “an equivalent 

method”.

Comment: Support for weight-of-evidence

Commenter (0160) supported allowing Moderate areas to use an alternative attainment 

demonstration approach such as weight-of-evidence (WOE). Commenter (0160) suggested this 

approach could include a combination of regional air quality modeling and data analysis 

techniques. Commenter (0160) noted that, in California, some rural Marginal areas may become 

Moderate in the future making it important to include this alternative attainment demonstration 

approach in the final rule. Commenter (0160) added that, use of air quality modeling done for 

upwind areas, transport analyses and other technical information could be included in a WOE 

approach. Commenter (0160) appreciated the flexibility to address SIP planning for Moderate 

nonattainment areas in a manner that is tailored to specific situations, providing an alternative to 

resource-intensive modeling for each Moderate area.

Response: The EPA agrees that an alternative attainment demonstration approach may in some 

cases substitute for photochemical modeling (with proper approval). But we wish to clarify that 

the EPA does not use the term “weight of evidence” (WOE) to specifically refer to such an 

approach. As used by EPA, WOE refers to a set of analytical information that supplements a 

modeled attainment demonstration. While there are analyses that could be included in a typical 

WOE demonstration that could potentially serve as alternative analytical method to 

photochemical modeling, WOE itself does not serve as an alternative. States are encouraged to 

submit WOE information to supplement their attainment demonstration. Any state contemplating 
23

an alternative analytical method to substitute for photochemical modeling must identify and 

document the method and seek formal approval from the EPA.

Comment: Do not support weight-of-evidence

Commenter (0180) stated that, because WOE determinations have often led to litigation or SIP 

disapproval, this method wastes limited state and EPA resources and impedes achievement of 

emissions reductions. Although the Commenter cited two cases in which the EPA prevailed 

regarding WOE, the Commenter (0180) stated that, the cases nonetheless indicate the limits of a 

weight of evidence approach and asserted the EPA’s guidance appears to violate the directive of 

Environmental Defense v. EPA, where the demonstration would, contrary to the court’s 

admonition, “abandon the model all together.”

Commenter (0180) stated that, the guidance would go far beyond legal bounds if the EPA 

allowed the modeled attainment test to be supplemented with evidence of unusual events that 

were not the “but for” cause of an exceedance. Commenter (0180) stated, the EPA must look at 

monitored values that reflect air quality at the time of the measurement, not values that are 

arbitrarily lowered if the state or the EPA believes the reading to be too high on a certain day. 

Commenter (0180) stated, Congress provided a mechanism through exceptional events (EE) for 

those situations to be addressed after they have occurred, once the facts can be evaluated, not in 

an anticipatory and speculative manner as the EPA describes it. Commenter (0180) objected to 

the EPA’s WOE approach because it appears to be designed to let states specifically ignore years 

like 2012 and the impacts of climate change in general. 

Response: The EPA disagrees with the comment that WOE analyses should not be allowed to 

support attainment demonstrations. While modeling is still the critical component of an 

attainment demonstration, there is always uncertainty associated with modeling results. WOE 

analyses are meant to support and supplement the modeling results. Many types of information 

can be used to demonstrate that expeditious attainment is likely. These include alternative 

modeling applications, ambient data analyses and trends, emissions analysis and trends and in 

some cases additional emissions controls that were not directly accounted for in the modeling 

demonstration. 

The Commenter notes cases where the EPA both approved and did not approve attainment 

demonstrations based on the combined strength of modeling and weight of evidence analyses. 

These examples illustrate that WOE arguments are sometimes convincing and sometimes not. 

EPA has approved attainment demonstrations with WOE demonstrations and has also disapproved demonstrations where the overall evidence does not support an approval. Contrary to 

the Commenter’s assertion, the EPA is not skeptical of WOE demonstrations. We recognize that 

some attainment demonstrations and WOE are convincing and some are not. The fact that we do 

not always approve attainment demonstrations is not a reason to abandon the WOE concept. 

In addition, the Commenter notes several court cases that support the ability to use WOE in 

evaluating attainment demonstrations. Since the EPA clearly has the legal authority to do so and 

since there are numerous technical reasons to evaluate as much data and information as 
24

appropriate, the EPA will continue to allow states to use WOE in support of modeled attainment 

demonstrations. 

Comments related to the Exceptional Events (EE) are addressed in section 2.B.5.

3. Modeling guidance

Comment: Commenters (0132, 0152 and 0154) requested that, the EPA update its ozone 

modeling guidance as soon as possible since modeling must be completed well in advance of SIP 

submission. Commenter (0152) stated that, too often the EPA modeling guidance is issued too 

late for states to meaningfully apply it to SIP submittals that are on strict deadlines. 

Response: The EPA agrees with the Commenters that, revised ozone photochemical modeling 

guidance is needed. A revised draft has been released for public comment and a final version will 

be released soon after the final implementation rule is published. 

4. Capturing high emissions days in inventories

Comment: Use a summer day emissions inventory

Commenters (0143, 0144, 0146 and 0167) stated that, the EPA should include the requirement in 

the rule that the baseline inventory for RFP and contingency measures should be a summer day, 

rather than an annual inventory. One Commenter (0167) commented that, a “high ozone season 

day” inventory be required. The Commenter indicated that, the EPA states in the proposed rule, 

“On December 4, 2008, the EPA promulgated the Air Emissions Reporting Requirements 

(AERR) rule (40 CFR 51, Subpart A). The AERR requires states to submit comprehensive 

statewide 3-year cycle emission inventories (2008, 2011, 2014, etc.) regardless of an area's 

attainment status. The EPA indicates it would be appropriate for states with periodic inventory 

obligations under 182(a)(3)(A) to rely on their 3-year cycle inventory as described in the AERR 

to satisfy their 182(a)(3)(A) periodic inventory obligation.” Ozone concentrations are most likely 

to be higher in the summer time since ozone concentrations are dependent on atmospheric 

conditions typical of a summer day. States depend on accurate summer day emissions of NOx

and VOC to develop atmospheric modeling runs. An accurate account of summer daily 

emissions is necessary for Pennsylvania's planning effort. The Commenter believed that, this is 

especially important if an air agency will also be required to model the effect of HEDD units 

which could elevate ozone concentrations on certain summer days. (0143)

Another Commenter (0144) contended that, current inventory guidance is inconsistent. The 

proposal and background section references the air emissions reporting requirements (AERR) for 

the purposes of defining the data elements for the emissions inventories for ozone relevant data 

element requirements, but the simultaneous AERR proposed amendments are removing the 

ozone related definitions and guidance. The background section of the proposal also references 

the EPA August 2005 inventory guidance document. This 2005 guidance document references 

and includes the consolidated emissions reporting rule (CERR), which no longer exists. States 

need clear guidance and definitions on ozone inventory development that is no longer obsolete. 

(0144)
25

Another Commenter (0146) requested that, the EPA expressly state that the baseline inventory 

for RFP and contingency measures be based on a summer day inventory, not on annual 

emissions. Such specificity was expressed in the previous ozone implementation rule as follows: 

“Consistent with the manner in which [rate of progress (ROP)] plans under the 1-hour ozone 

standard were developed, the RFP baseline for 2002 will have a typical summer day tons/day 

basis. As such, the attainment year target will also be a typical summer day target.” If the intent 

of the language in the proposal was to allow such elements to be based on annual inventories, 

then the EPA is misguided. If this is instead an error of omission, then the EPA must clarify the 

requirements with language consistent with that used previously. (0146)

Commenter (0167) stated that, the EPA’s proposed rule does not clearly state the baseline 

inventory requirements. The EPA’s proposed rule mentions only annual data inventory. OTC 

states firmly believe that a high ozone season day inventory is also required. The EPA should 

expressly state that the baseline inventory for RFP and contingency measures be based on a 

summer day inventory. (0167)

Response: The EPA agrees that the baseline inventory for RFP should be based on an actual 

summer day inventory, which is consistent with the existing AERR requirements of 40 CFR Part 

51 (the AERR). The EPA also partly agrees with the comment to use a “high ozone season day” 

inventory. In particular, the EPA agrees with the concept of an “ozone season day” inventory, 

because some areas have been observed to have exceedances during periods other than the 

summer season, which is typically when violations occur. Otherwise, the EPA believes that the 

existing definition is sufficient, which is supported both by those Commenters asking for a return 

to use of “summer day” emissions as well as by the progress achieved to date for reducing NOx

and VOC with the existing inventory approaches. Thus, the EPA disagrees with the addition of 

the word “high” to the “ozone season day” emissions.

Consequently, the EPA has included in the final rule the requirement that the inventories 

required by the CAA sections 182(a)(1) and 182(b)(1)(B) include actual ozone season day 

emissions, but has otherwise used a definition consistent with the “summer day” emissions 

definition previously in 40 CFR Part 51. Thus, ozone season emissions are defined in this final 

rule as an average day’s actual emissions for a typical ozone season work weekday. Also 

consistent with 40 CFR Part 51, this final rule specifies that the “ozone season” is defined by the 

state in consultation with the regional office. This approach adopts the previous approach in 40 

CFR Part 51 for the period defined as “summer,” but replaces “summer” with “ozone season.” 

The EPA also clarifies that the concept of “ozone season” for inventory purposes is not the same 

“ozone season” as that used for monitoring requirements. In general, the EPA expects that the 

period used for defining the ozone season for computing emissions inventories will be shorter 

and aligned with periods of the most significant ozone exceedances.

Comment: Require maximum daily emissions

Commenters (0144 and 0146) recommended that, the EPA address whether maximum daily 

emissions should be included in SIP planning. The Commenter (0144) stated that, the EPA 

should require a maximum daily actual emissions inventory during the ozone season to more 

accurately depict the cause of ozone exceedances, which are not predicted by an annual or 
26

typical ozone season day inventory; such an inventory would more accurately capture HEDD 

units and distributed generation units. (0144). Another Commenter (0146) expressed that, the 

EPA should consider requiring maximum daily emissions, such as HEDD emissions, during the 

ozone season to more accurately depict the cause of ozone exceedance. These emissions are not 

currently captured in an annual or typical ozone season day inventory. 

Response: While the first Commenter used the term “actual” in the comment and the second 

Commenter did not, we are assuming that based on the context in which these comments were 

given, both Commenters would like maximum actual emissions to be used as part of SIP 

planning. The context of both of these comments were for using emissions during HEDD 

periods, which we address in the response to the next comment summary.

In the final rule, we have indicated the need for areas to use emissions that are consistent with 

periods that have ozone exceedances. These periods can include HEDD periods for areas where 

emissions are higher during HEDD events. Rather than change the wording to include 

“maximum,” we have elected to take a similar approach as in past rules as encouraged by 

Commenter 0146. As described in the response to the previous comment, we are requiring ozone 

season day emissions, the definition for which the EPA believes achieves the intent of these 

Commenters to use emissions estimates from periods of high ozone. 

Comment: Require HEDD emissions in SIP planning

Commenters (0167 and 0168) recommended that the EPA require that HEDD emissions 

inventories be included in SIP planning. The Commenters recommended, as part of the high 

ozone day inventory, states need to factor in HEDD data into their modeling to appropriately 

factor in the impact of HEDD. The OTC states request that EPA take steps to account for and 

address peak emissions that contribute to high ozone days. (0167). Commenter (0168) agrees 

with the EPA proposal that, these emissions must be appropriately accounted for in modeling. 

Because of their significance we recommend that the EPA take a stronger stance in the proposal 

and clearly require areas to specifically address HEDD not only in modeling, but also in all other 

SIP requirements, to include ROP calculations and RACT determinations. (0168)

Response: The EPA agrees with the Commenters that HEDD emissions should be included in 

SIP inventories where appropriate. The EPA also agrees with the principle of a Commenter’s 

(0168) recommendation to include HEDD-related emissions in non-modeling inventories, but the 

EPA believes that such emissions are already required based on existing definitions and continue 

to be required by the final rule. 

The final rule requires a base year inventory for the nonattainment area in accordance with the 

CAA 182(a)(1) and 182(b)(1)(B) requirements for states to develop current and baseline 

inventories of actual emissions for the nonattainment area as part of SIPs. This “base year 

inventory for the nonattainment area” is used to form the baseline for ROP/RFP calculations and 

for motor vehicle conformity, as well as to provide an ozone season average overview of the 

current emissions sources. The emissions required for this base year inventory are ozone season 

day emissions as defined above and the spatial extent includes only the nonattainment area.
27

Furthermore, the final rule relies on 40 CFR Part 51 for defining which emissions are to be 

included in emissions inventories reported to the EPA. The current requirement for emission 

inventories in 40 CFR 51.20 (a) states: “All anthropogenic stationary sources must be included in 

your inventory as either point or nonpoint sources.” In addition, 40 CFR 51.20(d) further 

clarifies that “Nonpoint source categories or emission events reasonably estimated by the state to 

represent a de minimis percentage of total county and state emissions of a given pollutant may be 

omitted.” The EPA believes that for nonattainment areas for which emissions sources inside the 

area contribute emissions during HEDD periods, those emissions sources would not pass the de 

minimus test of 40 CFR 51.20 (d) and should therefore be included in the base year inventory for 

the nonattainment area. The EPA additionally recommends that the use of the phrase “typical” 

does not prevent areas from including emissions associated with HEDD events, particularly if the 

conditions causing nonattainment typically include HEDD-related emissions within the 

nonattainment area.

States are encouraged to examine emissions data and other information to determine if HEDD 

emissions sources need to be considered in their plan. As is the case with other emissions 

sources, it is inherently a state responsibility to develop emissions inventories, perform modeling 

(where necessary) and submit an attainment demonstration that shows how the state will attain 

the ozone NAAQS. It is also the state’s responsibility to ensure that the emissions and modeling 

accurately represent the conditions that form ozone in the area and will show that they will attain 

the NAAQS by their attainment date (for Moderate and above areas).

The EPA has also considered the possibility that the intent of these comments may include 

seeking to compel other states to include HEDD-related emissions in their inventories. Such 

emissions estimates could be needed by downwind states from upwind states to help characterize 

the downwind state’s nonattainment problems. However, since the purpose of the CAA 182(a)(1) 

and 182(b)(1)(B) emissions inventory requirements are to characterize the emissions within a 

nonattainment area that are needed for SIP development purposes for that nonattainment area, 

the EPA does not believe it should compel states to include HEDD-related emissions if those 

emissions are not relevant for bringing their own nonattainment area(s) into compliance. The 

resulting approach in this final rule allows for HEDD emissions to be included, but does not 

require them.

Comment: Create guidance and require emissions from the distributed generation sector 

for SIP planning

Commenter (0130) urged the EPA to provide specific guidance on the quantification of 

emissions from the distributed generation sector. The Commenter claimed widely available data 

from sources such as PJM seem to indicate that this emissions sector may be a segment of the 

emissions inventory that is currently under-estimated by the NONROAD model. Also important 

is the temporal and spatial profiles for this sector, which are poorly understood and could be 

important to air quality modeling. The Commenter contended it is known that such units operate 

during HEDD events and may emit NOx in quantities that could be of concern in the short term, 

yet no federal guidance exists for the quantification, temporalization and spatial allocation of 

emissions in the base year or the future attainment years from this category. Without such basic

information, estimating the impact on ozone air quality from this sector using EPA-approved 
28

models is not possible. (0130)

Commenter (0144) stated, the EPA should require data from uncontrolled diesel engines used for 

demand response purposes as a part of a demand side management program be incorporated into 

the inventories and the modeling. 

Response: The EPA agrees with the comments that distributed generation emissions could be 

important in some nonattainment areas. The EPA also agrees with the comment that emissions 

from uncontrolled diesel engines should be included in emissions inventories and modeling, but 

the EPA also believes that states are already required to do so under 40 CFR Part 51. The EPA 

disagrees with the comments that no guidance is provided for these sources of emissions and that 

it is not possible for states to estimate the impact on ozone from this sector without additional 

information from the EPA. 

As described in the response to the comments above (See “Require HEDD emissions in SIP 

planning”), the governing rule for which sources to include in emissions inventories is found in 

40 CFR Part 51. As with HEDD emissions, the EPA believes that these sources of emissions are 

already required and do not pass the de minimus test for being able to be excluded from 

inventories. Thus, the EPA concludes that the governing emissions reporting regulations already 

require the reporting of emissions from distributed generation where such emissions are 

important for analysis of ozone nonattainment. Because of the intermittent and smaller capacity 

of these sources, the EPA anticipates that they would be included as nonpoint sources, as an 

individual generator may be unlikely to meet the potential-to-emit point source reporting 

thresholds included in 40 CFR Part 51. However, states are permitted to get more detailed than 

required and include these sources as point sources.

Furthermore, the EPA disagrees with the implication that the EPA is required to provide 

information and emissions approaches for a given category prior to a state being able to include 

emissions in their SIP planning from that category. As is the case with other emissions sources, it 

is inherently a state responsibility to develop emissions inventories, perform modeling (where 

necessary) and submit an attainment demonstration that shows how the state will attain the ozone 

NAAQS. It is also the state’s responsibility to ensure that the emissions and modeling accurately 

represent the conditions that form ozone in the area and will show that they will attain the 

NAAQS by their attainment date (for Moderate and above areas). While the EPA can assist in 

preparing these estimates by publishing emission factors, compiling national inventories and 

producing emissions models, any lack of such information does not remove the state 

responsibility of complete emissions inventories for SIP planning purposes.

In addition to the comments on the rule requirements, this comment also reflects on the EPA’s 

guidance documents. While comments on the EPA’s guidance does not directly impact the 

outcome of the rule, the EPA addresses these comments here to be complete.

The EPA disagrees with the Commenter’s assertion that, no federal guidance exists for the 

quantification of emissions in the base year or the future attainment years for this category. 

Emissions from generator engines are covered in AP-42, Chapter 3, Section 3 provides emissions 

methods for these engines. As stated in that section: “The engine category addressed by this 
29

section covers a wide variety of industrial applications of both gasoline and diesel internal 

combustion (IC) engines such as aerial lifts, fork lifts, mobile refrigeration units, generators

[emphasis added], pumps, industrial sweepers/scrubbers, material handling equipment (such as 

conveyors) and portable well-drilling equipment.” The emission factors for NOx and other 

pollutants included in this AP-42 section are provided in two forms: power output (emissions in 

lb/hp-hr) and fuel input (emissions in lb/MMBtu). To use these emission factors, state and local 

air agencies can conduct surveys of their area to obtain the necessary activities of power output 

and/or fuel input. Such surveys are a typical part of the SIP planning process, especially for new 

or unfamiliar source categories.

The Commenter asserts that, the NONROAD emissions model underestimates the emissions 

from the distributed generator sector of the emission inventory. The EPA disagrees with the 

Commenter’s assertion. The NONROAD model only calculates emissions from a generator that 

is “trailer or skid mounted self-contained engine\electric generator designed to supply electric 

power at a job site. (User’s Guide for the Final NONROAD2005 Model, EPA420-R-05-013, 

December 2005, Table B-6)4 Therefore, NONROAD2008 should not be used to calculate 

emissions from generators that are installed at a fixed location. This is consistent with the 

definition of a nonroad engine, which states in part that an internal combustion engine is not a 

nonroad engine if the engine...remains or will remain at a location for more than 12 consecutive 

months or a shorter period of time for an engine located at a seasonal source. (40 CFR part 89.2)

The EPA also disagrees with the Commenter’s assertion that, no federal guidance exists for 

temporalization and spatial allocation of the distributed generation sector. These emissions 

allocation steps are particularly relevant for inventories used for modeled attainment 

demonstrations and temporal allocation may be important for estimation of ozone season 

emissions for the nonattainment area inventories. While the Commenter is correct that, there is 

no formulaic approach provided by the EPA for use in distribution generation emissions, the 

general guidance on temporal and spatial allocation of the emissions provided in the modeling 

guidance applies sufficiently for this sector. In addition, to the extent that distributed generation 

emissions are included in a state’s inventory as a nonpoint source, the EPA provides several 

spatial allocation surrogates that could be appropriate for this type of industrial/commercial 

source. In addition, local survey data would benefit the spatial allocation approaches. Lastly, 

temporal allocation of these types of emissions is highly specific to a given episode and 

electricity generation and so those local conditions should be considered. The EPA does not 

believe that any default temporal profiles would sufficiently describe the temporal nature of 

these sources given their specificity, intermittent use and variability from one ozone season or 

episode to the next. For areas where such distributed generation emissions are significant, such a 

local-specific approach is consistent with the temporal allocation guidance provided in the 

modeling guidance.

 

4 The user’s guide is available at: 

http://www.epa.gov/otaq/models/nonrdmdl/nonrdmdl2005/420r05013.pdf
30

Comment: State discretion

Commenter (0152) stated that, it should be up to the states to decide if HEDD days necessitate 

modeling.

Response: The EPA agrees that it is up to the states to decide if HEDD issues (selection of 

modeling time periods, emissions generation and control strategies) are important in their area 

and attainment demonstration. This final rule does not impose any new HEDD-related 

requirements for SIPs. It simply raises the issue so that states are aware that HEDD emissions 

could be important on some days in some areas. States are encouraged to examine emissions data 

and other information to determine if HEDD emissions sources need to be considered in their 

plan. As is the case with other emissions sources, it is inherently a state responsibility to develop 

emissions inventories, perform modeling (where necessary) and submit an attainment 

demonstration that shows how the state will attain the ozone NAAQS. It is also the state’s 

responsibility to ensure that the emissions and modeling accurately represent the conditions that 

form ozone in the area and will show that they will attain the NAAQS by their attainment date 

(for Moderate and above areas).

Comment: Reporting of HEDD emissions by industry for use in modeling

Commenter (0143) stated that, the EPA should utilize its existing authority under section 114 of 

the CAA to require owners or operators of all HEDD units to report their daily NOx emissions to 

the EPA and the EPA should publish that data for states to use in their atmospheric modeling 

analysis.

The Commenter believed that, the EPA indicates that the episode selection for the modeling 

should be used to address HEDD emissions timeframes by each state in which HEDD issues 

exist. The Commenter pointed that, in the proposed rule, the EPA stated, “Since NOx emissions 

from electric power generation are a significant contributor to the total NOx emissions for many 

ozone nonattainment areas, states that experience this phenomenon should be careful to fully 

account for it by ensuring that these emissions are included in photochemical modeling of 

episode days on which the phenomenon occurs. In order to properly account for HEDD 

emissions, careful attention should be paid to the temporalization of emissions to the specific day 

and hour of the day when these emissions occur (78 FR 34186).” The Commenter believed that, 

the EPA, however, fails to use its authority under section 114 of the CAA to either require 

reporting from companies that contract HEDD units or obtain the information that they are 

proposing the states obtain to perform the analysis and modeling. If companies were required to 

submit information to the EPA on the location of generating units with a power rating below 25 

megawatts, the associated emissions information from these units could be appropriately 

analyzed and modeled to determine if smaller HEDD units have an impact on air quality. This is 

especially important for distributed generation that is participating in a Demand Response 

Program. The EPA should request data from owners/operators of sources that do not currently 

report data to states or the EPA. After the EPA obtains this information, this data should be 

provided to states so they can use the data to determine appropriate control measures as needed. 

(0143)
31

Response: Section 182(a)(3)(B)(i) mandates States to include in their SIP a requirement that 

owners and operators of each stationary source of VOC and NOx emissions must provide to the 

state a showing of actual emissions of VOC and NOx from that source. The EPA acknowledges 

that it could use its authority under Section 114 of the CAA to require additional reporting of 

emissions when appropriate; however, adding such a reporting requirement would be outside of 

the scope and context of the final rule. Additionally, neither the CAA nor the EPA has 

determined a way to subcategorize electricity generating units into a class, as the Commenter 

suggest, of “HEDD units.” The EPA agrees that some units are used predominantly during 

HEDD periods, but classification of units based on when they are used is not a trivial exercise 

that the EPA believes can be resolved as part of this response. Nor can it be resolved as part of 

this rule.

The EPA disagrees that it needs to require additional reporting of location of generating units 

with a power rating below 25 megawatts. This information is available already through the 

database provided by the EPA entitled the “National Electric Energy Data System” database. The 

most current version (version 5.13) of this database is publicly available at 

http://www.epa.gov/powersectormodeling/BaseCasev513.html and includes a user’s guide. While 

the database does not explicitly include latitude longitude, it does include the state and county 

code and the ORIS Plant Code field that the EPA has used to match to the National Emissions 

Inventory, which does include the latitude/longitude locations.

Further, the EPA notes that one key aspect of the EPA’s identification of this issue in the 

preamble to this rule is that episodes selected for the modeled attainment demonstration should 

include HEDD periods and associated emissions when it is appropriate to do so. While the EPA 

agrees that quantifying all emissions associated with HEDD periods is difficult, the EPA believes 

that in most if not all cases, existing data collection programs provide enough information to 

identify the HEDD periods. After such identification, air agencies should then work to better 

quantify the emissions from important extra sources of emissions during these periods. The EPA 

points to existing EPA programs that require the use of Continuous Emissions Monitoring 

System (CEMS). While the emissions from all units operating during HEDD periods are not 

captured by the CEMS, the EPA believes that enough information is captured to identify HEDD 

periods and to determine if such periods are potentially contributing to ozone formation.

The EPA acknowledges challenges to estimating additional emissions during HEDD periods, but 

points to the following mechanisms as reasonable approaches to collecting more information. 

First, air agencies should collaborate with their state energy and public utility commission 

counterparts, who may have established (or can establish) mechanisms for information collection 

and sharing. Air agencies may also need to assess the demand response programs in their area by 

working directly with utilities and independent system operators (ISOs). Second, starting in 2015 

the National Emission Standard for Hazardous Air Pollutants (NESHAP) and New Source 

Performance Standards (NSPS) for Reciprocating Internal Combustion Engines (RICE) (40 CFR 

Part 60, Subparts IIII and JJJJ and 40 CFR Part 63, Subpart ZZZZ), also called the RICE rules, 

will require owners/operators of emergency engines participating in emergency demand response 

programs to report the dates and times that the engines operate for emergency demand response 

as well as engine information such as horsepower and model year. While the RICE rules do not 

require the reporting of NOX emissions or information about non-emergency programs, they will 
32

start to help provide information useful for understanding the activity of these back-up 

generators and engines, which may also be helpful for ozone planning purposes. 

Comment: States need guidance on HEDD periods for modeling issues

One Commenter (0130) stated that, states need other types of guidance on the analysis and 

regulation of units operating during HEDD periods. The Commenter provided an example that, 

since these units have relatively low ozone season emissions, RACT analyses and other types of 

controls generally are not cost effective given current guidance on the calculations of cost/ton 

metrics. Federal regulation and/or guidance on the application of various CAA requirements to 

these units would allow states to develop strategies for their control and would standardize the 

approach to these units across regions. (0130)

Commenters (0131, 0144 and 0177) recommended that, the EPA update its guidance to account 

for the potential for high contributions of emissions during HEDD.

Commenter (0131) referenced a study by Northeast States for Coordinated Air Use Management 

(NESCAUM. Air Quality, Electricity and Back-up Stationary Diesel Engines in the Northeast. 

August 2012) and stated that, given the potential of high contributions of NOx emissions during 

high electricity demand days, the EPA should revise its guidance to require consideration of 

emissions from emergency generators that participate in emergency demand response programs, 

particularly given their potential impacts on HEDDs and implications for attainment. The 

Commenter added that, the EPA should provide guidance on how states should quantify the 

amount of additional capacity dispatched during HEDD events that is attributable to exempt 

emergency generators, in light of the EPA's acknowledgement that little data exist on the number 

or location of such generators at this time. At the very least, the EPA should publish assumptions 

that states can use in the absence of such data to accurately assess the contribution from exempt 

emergency RICE participating in demand response programs to regional ozone formation, which 

assumptions, if used in a state's photochemical modelling, will be deemed acceptable by the EPA 

for purposes of attainment demonstration. (0131)

Commenter (0144) agrees that, HEDD emissions should be properly accounted for. The 

Commenter contended that, the EPA should update its modelling guidance to ensure accounting 

for daily peaks in HEDD usage and ozone levels. 

Commenter (0158) stated that, the EPA suggests that states experiencing the phenomena of 

HEDD should make efforts to include emissions during these days in photochemical modeling 

but believed the EPA should make clear that states must continue to follow the procedures 

identified in current EPA photochemical modeling guidance for ozone episode selection for 

attainment demonstration modeling purposes. The Commenter maintained that, while HEDD 

may coincide with high ozone days, HEDD events should not be the driving force behind 

episode selection. The Commenter pointed out that, the EPA also states it will consider whether 

additional updates to current photochemical modeling guidance are needed to address modeling 

of HEDD. The Commenter endorsed to the extent that, the EPA revises existing guidance to 

address HEDD issues, such revisions should be undertaken through a public review and 

comment process. 
33

Commenter (0177) encourages the EPA to consult with all eastern U.S. regional grid operators, 

state and regional modeling partners to obtain specific HEDD emissions profiles and develop 

explicit HEDD procedures for incorporation into the modeling guidance. The Commenter also 

notes that, the Eastern Regional Technical Advisory Committee (ERTAC) has gathered and 

analyzed available Electric Generating Unit (EGU) data to develop a tool that projects hourly 

growth rates in EGU generation during peak-demand times. The commenter claims this 

information could prove useful in developing appropriate procedures to more accurately simulate 

HEDD emissions in photochemical modeling. (0177)

Response: To address these comments, the EPA has assumed that all Commenters are referring 

to the modeling guidance and not the emission inventory guidance (some Commenters 

specifically state this while others do not). The EPA also notes that these are comments on 

guidance rather than comments on the ozone implementation proposal for which this response to 

comments document is intended. Nevertheless, the following response is included for the 

purposes of completeness and to provide these Commenters with more information regarding the 

EPA’s intentions for guidance related to HEDD emissions.

The modeling guidance provides information for states to use in creating the emissions for their 

modeled attainment demonstrations. This is in contrast to the emissions inventory guidance, 

which provides information for states to use in creating the nonattainment area inventories for 

the base year and projected attainment year. The inclusion of HEDD-related emissions in the 

nonattainment area inventories is addressed in the response above to separate comments on 

including such emissions in the nonattainment area inventories (See “Comment: Require HEDD 

emissions in SIP planning”).

The EPA believes that in answering these questions, it is important to clarify that the EPA has no 

expectation that the same emissions will be used in the nonattainment area inventories as are 

used in the modeled attainment demonstration. To the contrary, the EPA expects that these 

inventories will not be consistent in many cases. The inventories should be consistent where 

consistency makes sense, but there are valid reasons why the inventories would not be the same. 

These reasons are related to the purpose of the inventories. 

The purpose of the base year inventory for the nonattainment area is to form the baseline for 

ROP/RFP calculations and for motor vehicle conformity, as well as to provide an overview of 

the emissions sources in the nonattainment area relevant to the nonattainment problem. 

In contrast to the base year inventory for the nonattainment area, the purpose of the inventory 

used for the modeled attainment demonstration is to represent the actual emissions during the 

modeled episode. As many Commenters have noted, this period may include higher emissions 

from smaller electricity generating units that operate only on high electricity demand days and 

distributed generation sources. Since modeled attainment demonstrations use high ozone periods 

rather than an ozone season average conditions to help ensure future attainment, the emissions 

during those periods are unlikely to match the ozone season day emissions included in the 

inventories for the nonattainment area. The EPA believes that existing guidance and this final 

rule allow for inclusion of the HEDD-related emissions and distributed generation emissions in 
34

both the nonattainment area inventories and the inventories used for the modeled attainment 

demonstrations.

In addition, the EPA does intend to update the photochemical modeling guidance to specifically 

mention high electricity demand days as an issue when selecting time periods to model, 

generating emissions for modeling and selecting control strategies. Since attainment 

demonstration modeling and SIP submittals are the responsibility of the states, it is up to 

individual states to determine the importance of HEDD emissions in their nonattainment area 

(and the surrounding region) and whether HEDD emissions and emissions controls need to be 

considered in their demonstration. This responsibility includes collecting information needed to 

estimate emissions of these sources. As with any other source of NOx or VOC emissions, it is 

also up to the states to determine a set of controls that will demonstrate attainment by their 

attainment date.

Comment: Climate change

Commenter (0180) stated, the EPA needs to require states to model meteorology that reflects the 

impacts of climate change. Commenter (0180) stated, for example, 2012 was a very hot year for 

a large part of the country and had very high ozone levels and states should be using 2012 

meteorology in their modeling as it represents what may become more common as we suffer the 

effects of climate change. 

Response: The modeling guidance contains details on “episode selection” for ozone modeling 

applications. States should refer to the guidance when choosing base year modeling periods. In 

general, states should model ozone periods which are generally conducive to ozone formation 

and which are representative of observed design values. There have been several recent summers 

with above normal temperatures in some parts of the country. However, the impact of climate 

change on the meteorology in any particular year in any particular area is unclear. Therefore, we 

believe the current guidance recommendations are sufficient. Base modeling periods should be 

selected based on several criteria, the severity of meteorology being one of them. 

In addition, recent research indicates that there could be an ozone “climate penalty” in the future. 

Assuming temperatures will rise in the future due to climate change and that other 

meteorological variables may also become more conducive to high ozone concentrations, there 

could potentially be a need for more stringent emissions reductions to counteract the higher 

ozone potential from warmer conditions. However, there are significant uncertainties in the 

impacts of climate change on air quality. Generally, the analytical horizon for climate 

applications is on the order of 20 to 100 years, while the horizon for attainment demonstrations is

typically shorter. Additionally, the forcing mechanisms that drive near-term natural variability in 

climate patterns (e.g., El Nino, North American Oscillation) have substantially larger signals 

than the driving forces related to climate change over short time spans. Research also suggests 

that the variability between climate modeling platforms is larger than the variability between 

modeled climate scenarios. Given the relatively short time span between base and future year 

meteorology in most SIP demonstrations, the EPA is not requiring states to explicitly account for 

long-term climate change, but does suggest states consider potential impacts in their specific 
35

areas, when impacts are believed to be important.

5. Modeled attainment test

Comment: Modeling in unmonitored areas

Commenters (0137, 0151 and 0152) did not support the EPA’s proposal that states model 

unmonitored areas. Commenter (0137) stated that, if a state has a monitoring plan that has been 

approved by the EPA, then use of the modeled attainment test in unmonitored areas should only 

be performed at the discretion of the state. Commenter (0152) stated that, attainment tests should 

be performed at monitored locations where real world checks can occur to confirm the accuracy 

of the model. Commenter (0151) stated that, additional modeling of areas that lack monitors only 

should be done if the state has a reason to believe that a number of people are likely to be 

exposed to ozone concentrations above the standard or there are large and/or clustered VOC/NOx

emitters that may be contributing to those excursions unhealthful air. Commenter (0151) 

asserted, the EPA already presented guidance adopting such a strategy for modeling of the SO2

NAAQS. Even though ozone is a regional pollutant, in contrast to SO2, which tends to have more 

localized effects, Commenter (0151) believed, that requiring statewide modeling is neither 

needed nor required by the Act. 

Commenter (0180) stated, the EPA should clarify in its regulations that the ozone attainment 

demonstration modeling must include a receptor grid that covers the entire nonattainment area 

and that the design value for all receptors in the attainment year must be below the 2008 ozone 

NAAQS. Commenter (0180) asserted that, 42 U.S.C. § 7502(c)(1) provides that nonattainment 

SIPs must provide for “attainment of the national primary ambient air quality standards” and that 

42 U.S.C. § 7511a(c)(2)(A) contains a similar requirement. Commenter (0180) stated that, only 

modeling for modeling receptors at ambient monitoring locations is arbitrary and capricious 

because it ignores whether there will be attainment throughout the nonattainment area except for 

the tiny percentage of the nonattainment area where the ambient monitors are located. 

Commenter (0180) believed, this could result in subjecting millions of people to unsafe ozone 

levels because they happen to live, work or exercise in areas not right next to an ambient 

monitoring location. 

Response: The EPA continues to require a modeling analysis of future year ozone 

concentrations in locations with current or recent ozone monitors. In the proposed rule, the EPA 

also recommended for states to perform an attainment test in unmonitored areas. The 

recommended attainment test methodology for unmonitored areas has been used in 8-hour ozone 

SIPs developed for the 1997 ozone NAAQS. The EPA continues to believe that this is a valid 

approach. To make it easier for states to apply the attainment tests, both the monitor-based test 

and the unmonitored area test have been incorporated in a software package called the “Modeled 
36

Attainment Test Software.”5

Under the CAA section 110(a)(2)(B), all states are required to have an approved monitoring 

plan. The EPA’s monitoring requirements for ozone are designed to ensure a robust nationwide 

monitoring network in both nonattainment and attainment areas. Air agencies have done this by 

maintaining their ozone networks in accordance with the EPA’s network design criteria. These 

criteria provide that Core Based Statistical Areas (CBSA’s) have at least one ozone monitoring 

site located in a location of expected maximum concentration. Thus, by assuring compliance 

with the NAAQS at the expected highest concentration area, air quality is protected throughout 

each CBSA. However, due to limited resources, there are limits to the number of air quality 

monitors that can be deployed and it therefore may be useful to consider, what, if any additional 

monitoring needs there may be as agencies prepare their implementation plans.

6

The EPA proposed to require states to follow the existing modeling guidance which 

recommended a modeled attainment test where states demonstrate attainment at ambient 

monitors. The guidance also recommends that states conduct further analyses based on the 

modeling results to determine whether there are unmonitored areas that merit additional analysis 

or investigation. We believe this approach was appropriate, but the requirements for the 

unmonitored area analysis in the 2007 modeling guidance were not entirely clear. We are 

therefore clarifying the treatment of model results in unmonitored areas and will update the 

modeling guidance to reflect the latest recommendations on handling and documenting the 

results of an unmonitored area analysis. In the final rule, the attainment test must be performed at 

current or recent monitor locations. An unmonitored area analysis is not required as part of the 

attainment demonstration. However, we continue to recommend states perform an unmonitored 

area analysis and encourage states to use information available to them to determine the 

likelihood of violations in unmonitored areas. This may be especially important in areas with a 

relatively sparse ozone monitoring network or in locations where information such as modeling, 

emissions, or other monitoring data may indicate potential high ozone concentrations in areas 

that are currently unmonitored. 

 

The EPA does not believe that the CAA requires states to specifically determine through 

modeling that attainment has been shown in unmonitored areas. The CAA section 172(c)(1) 

 

5 The Modeled Attainment Test Software is available for no charge at: 

http://www.epa.gov/scram001/modelingapps_mats.htm.

6 Annual monitoring network plans and 5-year assessments are required by regulation in section 

58.10. The 5-year monitoring network assessment is a comprehensive evaluation of the 

monitoring agencies ambient air monitoring network, while the annual plans describes the 

existing network and changes being proposed to support implementing recommendations from 

the most recent 5 year assessment as well as any applicable changes from revisions to NAAQS.
37

requires the SIP to provide for attainment of the 2008 ozone NAAQS and the CAA section 

182(b)(1)(A)(i) requires the SIP to provide for annual reductions in emissions of VOC and NOx

as necessary to attain the NAAQS. The EPA requires states to show that they are attaining the 

ozone NAAQS by showing that they are attaining at monitoring locations which are 

representative of air quality in the entire nonattainment area. 

Determining future year attainment at monitoring locations is consistent with how attainment of 

the ozone NAAQS is determined for purposes of designations and redesignations. The EPA 

promulgates designations for ozone NAAQS nonattainment areas based primarily on ambient 

data measured at monitors.7 Although the EPA considers other forms of information for purposes 

of evaluating areas with sources that contribute to those monitored violations for inclusion within 

the nonattainment area boundaries, the fundamental basis for a designated nonattainment area is 

the presence of one or more monitors with data showing violations of the NAAQS in question. 

Similarly, determinations of attainment of the ozone NAAQS for purposes of redesignation 

actions are based primarily on monitored data. When all ozone monitors in a nonattainment area 

measure attainment of the NAAQS, the area is eligible to submit a redesignation request, 

assuming compliance with the other requirements for redesignation. The EPA’s approval of a 

redesignation request is subject to meeting the requirements of the CAA section 107(d)(3)(E). 

Among those requirements is that the area has attained the NAAQS. For the ozone NAAQS, this 

determination is based on ambient data measured at the ozone monitors in the area in question. 

Thus, neither ozone designations nor redesignations are premised upon whether there are 

violations of the NAAQS at unmonitored locations throughout a given area. Therefore, 

consistent with how ozone areas are designated and redesignated, the EPA is only requiring that 

states show attainment at ozone monitoring locations as an element of their attainment 

demonstration for the ozone NAAQS.

In addition, the “relative” attainment test for ozone uses ambient ozone monitoring data, 

combined with future year modeled percentage changes in ozone concentrations, to project future 

year design values. Since the attainment test relies on ambient monitoring data, an analysis of 

future year concentrations in unmonitored areas can only be accomplished by interpolating 

ambient data to a particular location where there is no existing monitor or recent monitoring data. 

Therefore, in the context of an attainment demonstration, the projection of future year ozone 

concentrations in unmonitored locations is inherently more uncertain than projections in 

monitored locations due to the fact that the ambient concentrations from which these projections 

are developed are unknown in the unmonitored locations. 

States should consult with their EPA Regional Office to determine if an unmonitored area 

analysis should be conducted for a particular nonattainment area. Where an unmonitored area 

analysis is performed, states should use the unmonitored area analysis results to develop an 

assessment of the likelihood of violations in unmonitored areas. The nature of the assessment 

 

7 Determinations are based on design values which is an average of 3 years of ambient data. A 

monitor must have 3 years of ambient data to be used to determine compliance with the NAAQS.
38

depends on the local area modeling, but could include, as appropriate, elements such as an 

evaluation of the emissions inventory, the existing ambient data for the area and meteorological 

model inputs to determine if the modeled violations in unmonitored areas appear to be credible. 

If potential violations are found to be credible, additional steps may include imposition of 

enforceable emissions reductions at nearby emission sources or a commitment to deploy special 

purpose monitors and/or saturation monitors in the area (in order to further evaluate the 

problem). The state should document the assessment, including analyses of emissions, 

meteorological inputs and ambient data and/or make a commitment to establish special purpose 

monitors as part of the attainment demonstration. Special purpose ambient air monitoring data 

that is collected after the attainment demonstration is submitted should be summarized for use in 

the area’s 5-year monitoring assessment and where appropriate, annual monitoring network 

plans.8

Comment: Regional modeling 

Commenter (0141) stated, RAPCA does not have direct responsibility for the modeling and 

attainment demonstration; that responsibility falls to Ohio EPA. Given the limited resources 

available to many agencies today, the Commenter recommended maximum flexibility on this 

issue including the allowance of regional modeling plans covering large area as conducted either 

by the EPA or regional planning organizations such as LADCO.

Response: The EPA intends to allow flexibility regarding the nature of the modeled attainment 

demonstration. We understand that there are limited resources to conduct modeling. We urge 

RAPCA to closely coordinate with Ohio EPA, the EPA and LADCO to ensure that any 

attainment demonstration modeling requirement is adequately satisfied for the area. 

Comment: Discourage across-the-board reductions

Commenter (0151) requested that, the EPA actively discourage states from imposing another 

round of proportional “across-the-board percentage VOC and/or NOx reductions” on stationary 

sources based on their estimate of needed area-wide ozone reductions in the final rule because 

regulators now know so much more about the interactions of NOx, VOC and the reactivity of 

different VOC in different air-sheds. A number of jurisdictions, according to Commenter (0151), 

thought such an approach was more politically viable for meeting the 1997 ozone NAAQS, but it 

appears arbitrary legally and even less likely to work for meeting the 2008 ozone NAAQS and 

could result in more pollution. Commenter (0151) believed, states have to be encouraged to take 

a look at the reactivity of the VOC and the likely impact of VOC reductions on actual ozone 

concentrations before requiring addition controls for the sake of controls. 

 

8 All states are required to have an annual monitoring plan which meets the siting criteria for 

ozone monitors (40 CFR 58.10). 
39

Response: States should use science-based judgments to determine the appropriate mix of NOx

and VOC controls that are necessary to bring an area into attainment. The purpose of an 

attainment demonstration is to identify the emissions reductions that are needed by states to 

attain the NAAQS as expeditiously as practicable. However, as detailed in the RFP, ROP and 

RACT sections of the final preamble, the CAA section 182 requires a certain percentage 

reduction in area-wide VOC and/or NOx emissions for Moderate and above areas for RFP. See

sections C and D in Part 2 of this document for more details. Any additional VOC and/or NOx

reductions needed to show attainment can come from any source sector, in any amount that is 

found to lead to expeditious attainment.

Comment: EE proposal

Commenters (0130, 0132, 0159 and 0173) generally supported the EPA’s approach for the 

upcoming Modeling Attainment Test guidance, footnote 20 (78 FR 34186), that may allow the 

adjustment of air quality data to remove the effect of EE from the ozone design values. 

Commenter (0130) added that, guidance on the application of the Exceptional Events Rule 

(EER) to ozone exceedances is needed. 

Commenter (0132) stated, the adjustment of monitored ozone values needs to be carefully 

evaluated and should only be based on scientifically validated unusual natural events and 

catastrophic occurrences, whether human-caused or not. Regarding the EPA’s suggestion, at 

Footnote 20, of an alternative method for calculating future design values for WOE 

determinations by adjusting monitored air quality days if influenced by unusual natural or 

anthropogenic events, Commenter (0132) stated that, without specific and limited definition 

criteria, any day could be interpreted to be influenced by an unusual event. 

Commenter (0132) supported the exclusion of days impacted by major industrial accidents, such 

as refinery fires, as well as foreign transport or other unusual natural events or events outside the 

control of the state, from the calculation of baseline design values, since it would be 

inappropriate to include effects of such rare but extreme events in the development of control 

strategies. 

Commenter (0151) requested the EPA to address how states should handle EE that contribute to 

ozone nonattainment in this round of SIP planning. Commenter (0151) noted that, the EPA 

proposed revisions to its EE policy in 2012 and that a final policy is critical for states to flag and 

exclude excess ozone values caused by EE from 2008 NAAQS SIP planning. 

Commenter (0180) stated, the EER was overbroad and the guidance goes beyond legal bounds, 

swallowing the WOE demonstration and the attainment demonstration. Commenter (0180) 

believed the EPA seems to acknowledge as much, since the agency “expects that there will be 

limited situations where this potential adjustment would make a difference between future year 

estimated attainment and nonattainment.” Commenter (0180) stated, the EER is an example of 

the harms wrought by similar exclusions and asserted Congress crafted a narrow definition of 

“exceptional event,” reserving the term for certain extraordinary natural events and for human 

activities that are “not reasonably controllable or preventable” and “unlikely to recur at a 
40

particular location.” 42 U.S.C. § 7619(b)(1)(A). 

Response: The EPA does not intend to update its guidance on attainment demonstrations, 

Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality 

Goals for Ozone, PM2.5 and Regional Haze (April 2007), to permit states to supplement their 

attainment test with evidence that could include recently monitored values that have been 

adjusted to better represent the air quality that would have existed in the absence of any unusual 

natural or anthropogenic events (if any) that influenced (ozone/PM2.5) concentrations on the 

monitored day(s). While analysis of ambient data related to EE can be an appropriate component 

of a weight of evidence demonstration, EPA believes it is premature to formally allow such 

ambient data adjustments without first addressing this issue through revisions to the EER 

anticipated to be proposed in mid-2015 and finalized in mid-2016. The photochemical modeling 

guidance will continue to recommend adjustments to ambient data as allowed under the EER and 

as otherwise appropriate as part of a weight of evidence analysis. 

Comment: Request for clarification

Commenter (0155) requests that, the EPA clarify in footnote 15 on p. 34185, relative to multistate nonattainment areas, that the requirement to prepare an attainment plan applies only to 

Moderate and above areas and not to all multi-state nonattainment areas.

Response: The EPA agrees that the requirement to prepare an attainment plan only applies to 

Moderate and above areas. Marginal nonattainment areas are not required to submit an 

attainment demonstration and are therefore not required to perform photochemical modeling.

Comment: Flexible modeling approach

Commenter (0162) endorsed a flexible attainment demonstration approach that recognizes the 

site-specific nature of each nonattainment area and the need to tailor emission reduction 

strategies based on local, site-specific factors. Commenter (0162) supported the use of sciencebased judgments to determine the appropriate mix of NOx and VOC controls that are necessary 

to bring a nonattainment area into attainment on schedule rather than having to rely on an acrossthe-board VOC reduction strategy. Commenter (0162) stated that, ample evidence shows that a 

tailored control program is much more effective in reducing ozone concentrations than an 

inflexible, across-the-board program and such a program should apply to RACT/RACM control 

decisions as well as any new RFP requirements. 

Commenter (0162) further supported a flexible modeling approach that would allow states 

preparing attainment SIPs to take credit for emission reductions from existing federal programs 

and for on-the-way federal programs that will be implemented before the first attainment 

deadline, thus minimizing need for additional state-specific control requirements.

Response: The EPA agrees in part and disagrees in part with the comments. The EPA agrees 

that states should use science based judgments to determine the appropriate mix of NOx and 

VOC controls that are necessary to bring an area into attainment. The purpose of an attainment 

demonstration is to identify the emissions reductions that are needed by states to attain the 
41

NAAQS as expeditiously as practicable. This can include emissions reductions from Federal 

programs that achieve emissions reductions before the area’s attainment date. However, as 

detailed in the RFP, ROP and RACT sections of the preamble, the CAA section 182 requires all 

Moderate and above areas to meet certain minimum percentage reductions in VOC and/or NOx

emissions in the nonattainment area. See sections C and D of Part 2 on this document for more 

details. Any additional VOC and/or NOx reductions needed to show attainment can come from 

any source sector, in any amount that is determined to be expeditious attainment. 

Comment: Over-prediction by models

Commenter (0159) stated that, the agency should not push states to rely on the EPA’s models as 

part of attainment demonstrations and did not support the use of modeled data when monitored 

data is available. Commenter (0159) asserted that, current models for attainment demonstrations 

have an unacceptably high margin of error. Commenter (0159) noted that, just recently, the 

model used by the EPA as part of the CSAPR rule had to be technically adjusted several times to 

“address discrepancies in unit-specific modeling assumptions that affect the proper calculation of 

Transport Rule state budgets and assurance levels in” several states, including Louisiana. See 

EME Homer City Generation v. EPA, 696 F.3d 7, 19 (D.C. Cir. 201 2). See also 77 FR 10,324 

(Feb. 2 1, 201 2). Commenter (0159) asserted that, the EPA's models over predict air quality 

problems. 

Response: The EPA disagrees with the Commenter. Photochemical grid modeling is the most 

technically credible scientific technique to estimate future NOx and VOC emissions reductions 

that are needed to attain the NAAQS in an expeditious manner. Ambient monitoring data cannot 

be used to project future ozone concentrations. To clarify, when the commenter uses the term 

“model,” it appears that they are referring to the Integrated Planning Model (IPM), which is used 

to generate future year emissions from EGUs. These are among many emissions inputs used in 

photochemical models. When performing photochemical modeling, states must project EGU 

emissions to the future modeling year, but they are not required to use IPM. Although IPM has 

been used extensively by the EPA in modeling analyses to support national rules, states have the 

flexibility to use whatever model or projection technique they believe is most credible to 

generate future year emissions for input to a photochemical model. 

6. Future years to model

Comment: Commenter (0130) suggested that, the EPA consider the difficulty and practicality of 

changing attainment years in their discussion of RACM and of attainment year determination. 

Commenter (0130) agreed that, this is a literal interpretation of the CAA requirements for 

RACM and attainment dates, but stated that, in practice, base years and future projection years 

must be chosen well in advance of the actual development of the RACM analysis and the 

attainment SIP submittal; due to the extensive work needed to develop a defensible base year 

inventory and meteorological data files for input into the CMAQ model. 

Commenter (0159) supported the proposal that, for the 2008 ozone NAAQS, control measures 

relied upon to demonstrate attainment should be implemented by the beginning of the last full 

ozone season prior to the area's attainment date. Commenter (0173) requested that, the EPA 
42

clarify that the ozone season to be modeled should be the ozone season during the attainment 

year. Commenter (0179) agreed that, the future modeling year should be selected such that all 

emissions control measures relied on for attainment will have been implemented by that year. 

Commenter (0152) disagreed with the EPA’s statement that control measures relied upon to 

demonstrate attainment should be implemented by the beginning of the last full ozone season 

prior to the area's attainment date. Commenter (0152) believed there may be scenarios where this 

is not plausible or necessitated; e.g., there could be a reliance on shutdowns from large sources to 

demonstrate attainment and the shutdown date may not fall precisely at the beginning of the last 

full ozone season. Commenter (0152) stated, it should not matter when the control measure is 

implemented if the demonstration shows attainment by the attainment date. 

Commenter (0159) did not support a rule that, requires nonattainment areas to demonstrate 

attainment prior to the dates set forth in the CAA section 181(a). To the extent that this proposal 

could be viewed to require that the demonstration of attainment be required earlier than is 

required by statute, Commenter (0159) objected to this proposal. 

Response: Most Commenters supported the proposal to allow modeling of the last year of the 

statutory attainment date. As requested, by way of clarification, for a Moderate area with a 6-

year attainment date the state would be able to model the 6th year after designation. Controls 

needed for attainment must be in place by the beginning of the ozone season that is being 

modeled. The EPA agrees with these Commenters that modeling of the final year of the statutory 

attainment date is reasonable. Even though attainment is determined by averaging 3 years of 

ambient data, states do not have to model 2 years before the attainment date to show modeled 

attainment. Since the design value is an average of 3 years of data, attainment can still be shown 

even if concentrations exceed the NAAQS in one or two of the 3 years used to determine 

attainment (as long as the 3 year average is less than the NAAQS). Therefore, it can be 

appropriate to model any of the 3 years used to determine attainment. Also, if ambient data 

shows attainment level concentrations in the final statutory attainment year, a state may be 

eligible for up to two 1-year extensions of the attainment date, if the area meets the criteria for 

such extensions. Therefore, modeling attainment level concentrations for the last year permitted 

by statute is acceptable. 

We disagree that it is not also necessary to analyze potential emissions controls in earlier years as 

part of a RACM analysis. Despite the maximum statutory attainment date, all attainment dates 

are “as expeditious as practicable.” In spite of Commenters’ discussion that modeling or 

analyzing emissions controls in earlier years is difficult, time consuming and/or not necessary, 

the attainment demonstration must include a demonstration that attainment cannot be advanced. 

The EPA wants to clarify that a RACM analysis could include modeling of earlier attainment 

years, but modeling is not required. 

States are not required to submit an attainment demonstration for Marginal areas and therefore 

are not expected to submit modeling to support their attainment date. Because attainment 

demonstrations are not required, Marginal areas are also not subject to specific RACM or RFP 
43

requirements. But even though they do not have to do a RACM analysis, all nonattainment areas, 

including Marginal, have to attain the NAAQS as expeditiously as practicable.

One Commenter questioned whether all emissions reductions needed for attainment need to be in 

place by the beginning of the attainment year ozone season. They argued that it should not matter 

when the control measure is implemented if the demonstration shows attainment by the 

attainment date. The EPA believes the explanation in the proposed rule was appropriate, which 

says that control measures relied upon to demonstrate attainment should be implemented by the 

beginning of the last full ozone season prior to the area’s attainment date. To be clear, emissions 

control measures may be implemented during the last full ozone season or in later years, but 

emission controls that are used to demonstrate attainment in the modeled attainment 

demonstration must be implemented by the beginning of the last full ozone season. 

Comment: Modeling to advance the attainment date

Commenter (0180) noted that, most SIPs only model attainment for the final year and do not 

provide any data necessary to evaluate the potential for earlier attainment. To carry out the 

statute that RACM be implemented and provide for attainment, as expeditiously as practicable, 

42 U.S.C. § 7502(c)(1), Commenter (0180) asserted, the EPA must require that modeling also 

demonstrate what emissions reductions would be necessary to advance attainment by each year 

remaining in the period. Commenter (0180) believed this additional data essential to lawful and 

rational decisions regarding RACT and RACM, and the demonstration that the “as expeditiously 

as practicable” mandates in the statute are met. 

Response: The EPA agrees that states must perform a RACM analysis to determine if the 

attainment date can be advanced. However, the EPA disagrees that modeling for multiple years 

must be used to estimate the ozone reductions that can be achieved from potential RACM 

controls. The EPA believes that it is not reasonable to require states to model each and every 

year to determine the appropriate attainment date. Developing and modeling future year 

inventories is a time-consuming and resource intensive process. Multiple emissions models are 

needed in order to generate year-specific emissions for the various emissions sectors (e.g., 

mobile, non-road, non-EGU point, EGU point, etc.). In some cases it may be reasonable to 

model one additional interim year before the maximum statutory attainment date. However, in 

most cases, the air quality benefits of an identified set of RACM controls can be estimated 

through development of transfer factors (factors to relate tons of emissions reductions in the area 

to ozone concentration changes in the area). For example, states can model across the board 

percentage reductions in NOx and/or VOC emissions to determine the impact of emissions 

reductions on ozone concentrations in the area. This modeling can be performed with a single 

attainment modeling platform, which is much less resource intensive than modeling additional 

future years. The identified potential emissions reductions available from RACM can be 

compared to the magnitude of the modeled ozone reductions from the sensitivity analyses to 

determine if all such controls will advance attainment by at least a year. In some cases, emissions 

reductions from identified RACM measures may be so small that modeling would not be 

necessary to determine that attainment would not be affected by the available local controls. The 

EPA strongly recommends that states discuss the selection of the future year(s) to model with the 
44

appropriate EPA regional office as part of the modeling protocol development process.

Comment: Support original 4-year timeline for developing a meaningful attainment 

demonstration

Commenter (0157) stated, the EPA severely underestimates the time required to produce a 

meaningful attainment demonstration and believed the original 4-year timeline allows sufficient 

time to select a proper base year and provide the time needed to quality assure the variety of 

inventories needed to complete the modeling demonstration. Commenter (0157) attached a longterm study of ozone showing that every 3 or 5 years an ozone season occurs with a greater than 

average number of ozone violations, often followed by a lower than normal year. 

Thus, Commenter (0157) stated, it is important to select a year that will demonstrate the selected 

control measures that will provide adequate relief even in a high pollution year. Commenter 

(0157) believed, the EPA appears to disregard the cyclic nature of ozone in development of 

several areas in this guidance. Although the most recent triennial inventory year can be selected, 

Commenter (0157) stated that, year is not always the most appropriate year to select as a base 

year to ensure the attainment demonstration is adequate to protect against high ozone pollution 

years. Although it may take longer to select a year that ensures more than average ozone 

pollution, Commenter (0157) stated, the resulting control scenario is more robust and protective. 

Commenter (0157) asserted, the OTC states have been concerned that current modeling does not 

accurately represent HEDD emissions and have developed new models to better represent the 

electricity generation sector. These models, according to Commenter (0157) will be tested in the 

upcoming attainment demonstrations under this standard and may require additional time to 

model successfully and that, as generators may be one the categories regulated for RFP purposes 

under this standard, this is a very significant part of the attainment demonstration.

Response: Section 182 contains two attainment demonstration submittal dates, 3 years from the 

designation date for Moderate areas (182(b)) and 4 years from the designation date for Serious

and above areas (182(c)). The Phase 2 rule established regulations (See 40 CFR 51.908(a)) that 

required all attainment demonstrations to be submitted within 3 years of designation. However, 

the EPA proposed in the SIP Requirements Rule for the 2008 NAAQS to allow the original CAA 

deadlines of up to 3 years for Moderate areas and up to 4 years for Serious and higher classified 

areas. While EPA agrees that the development of emissions inventories and modeling for 

attainment demonstrations can be a lengthy process, the statute does not allow for more than 3 

years for a Moderate area attainment demonstration. However, since the statute does allow up to 

4 years to submit a Serious (and above) area attainment demonstration, in the final rule we are 

allowing the full amount time granted by the statute for such areas. Therefore, EPA is finalizing 

the attainment demonstration submittal dates as proposed; up to 3 years from the effective date 

of designation for Moderate areas and up to 4 years from the effective date of designation for 

Serious and above areas. 

C. What are the RFP requirements for the 2008 ozone NAAQS?
45

NOTE: The CAA contains three separate provisions regarding RFP. Section 172(c)(2) under 

subpart 1 contains a general requirement that nonattainment plans require RFP, while sections 

182(b)(1) and (c)(2) under subpart 2 contain specific percent reduction targets for Moderate and 

above and Serious and above areas, respectively. Section 182(b)(1) of the CAA requires all 

ozone nonattainment areas classified as Moderate and above to submit a SIP which describes, in 

part, how the areas will achieve an actual VOC emissions reduction of at least 15 percent during 

the first 6 years after being designated as nonattainment. The portion of the SIP revision that 

illustrates the plan for the achievement of this emission reduction was subsequently defined as 

“rate-of-progress (ROP) plan” in the past. In this document, the EPA will refer to the 

requirements for Moderate and above areas identified in the CAA section 182(b) that requires a 

15 percent reduction in VOC emissions from the baseline emissions over the 6-year period 

between designation and the Moderate area maximum attainment date as the ROP requirement. 

Also, the EPA will refer to the requirements for Serious and above areas contained in section 

182(c)(2), which require an additional 3 percent per year beginning 6 years after designation 

until the attainment date, as the RFP requirement.

1. 2008 ozone nonattainment areas for which no portion of the area has previously been 

required to meet the 15 percent RFP requirement for VOC

Comment: Support showing of 15 Percent VOC reduction from 1990 

Commenter (0130) stated that, for areas without a previously submitted 15 percent VOC 

reduction plan from 1990, the EPA should use national emission inventories to show that all 

areas of the United States (U.S.) have substantially met this CAA requirement, rather than 

requiring each area to make a submittal on the topic. Commenter (0130) stated that, the EPA 

should be able to use available data to show that this requirement has been substantially met by 

all areas. Commenter (0146) stated that, the EPA can best provide flexibility and ease state 

burdens for developing 15 percent plans by providing states with 15 percent plan templates, 

supporting documentation on federal measures that can help demonstrate already achieved VOC 

reductions. Commenter (0152) stated that, the 15 percent RFP requirement should be gauged 

against only the 1990 baseline in all circumstances as the EPA’s proposal is inconsistent and not 

the intent of the CAAA. Commenter (0159) supported allowing an area to meet the 15 percent 

RFP requirement in whole or in part with NOx reductions in lieu of VOC reductions if that area 

can demonstrate that it has in fact achieved a 15 percent reduction in VOC emissions from a 

1990 baseline. Commenter (0163) stated that, areas within the OTR, including new 

nonattainment areas, that have already implemented VOC control measures, such as RACT, 

motor vehicle inspection and maintenance programs, and Stage II or comparable measures, in 

response to statutory requirements, can be assumed to have met and would not have to document 

meeting the 15 percent RFP requirement. 
46

Response: Designated 2008 ozone nonattainment areas9that have neither been subject to nor 

have adopted and implemented a SIP providing for the section 182(b)(1) 15 percent VOC 

emission reductions, will be subject to the 15 percent ROP requirement in section 182(b)(1). We 

are finalizing that where a state has previously submitted, adopted and implemented a SIP 

providing for a 15 percent reduction in VOC emissions from a nonattainment area’s baseline 

emissions within 6 years following the baseline emissions inventory year, that area is allowed to 

meet the 15 percent ROP requirement in whole or in part with NOx reductions in lieu of VOC 

reductions. For 2008 ozone nonattainment areas, the EPA is not finalizing either of the 

approaches that would have allowed areas that have not previously provided a 15 percent VOC 

emission reduction within six years to meet the 15 percent ROP requirement in whole or in part 

with NOx reductions in lieu of VOC reductions. 

Comment: Supports inclusion of NOx reductions in progress demonstrations.

Commenter (0160) agreed with the proposed alternative that would allow newly classified 

Moderate areas to substitute NOx for VOC in the 15 percent plans and further stated that, since 

the enactment of the 1990 CAA amendments, the scientific understanding of the relative roles of 

VOC and NOx control has improved and strongly supports the inclusion of NOx reductions in 

progress demonstrations. (0160)

Response: The EPA appreciates the Commenter’s support. The EPA has interpreted the 

requirements of subpart 2 as they would apply to areas for the 1997 ozone NAAQS. We are now 

following the same interpretation with regard to the 2008 ozone NAAQS. With respect to RFP 

requirements, we interpret the 15 percent VOC emission reduction requirement in section 

182(b)(1) such that an area that has already met the 15 percent requirement for VOC reductions 

under either the 1-hour ozone NAAQS or the 1997 8-hour ozone NAAQS (for the first 6 years 

after the RFP baseline year for the 1-hour ozone NAAQS) would not have to fulfill that 

requirement again. Instead, such areas would be treated like areas covered under section 

172(c)(2) if they are classified as Moderate for the 2008 standard and would need to meet the 

RFP requirements under section 182(c)(2)(B) if they are classified as Serious or above for the 

2008 ozone NAAQS.10 For the purposes of the 2008 ozone NAAQS, the EPA is interpreting 

section 172(c)(2) to require such Moderate areas to obtain 15 percent ozone precursor emission 

reductions over the first 6 years after the baseline year for the 2008 ozone NAAQS and is 

interpreting section 182(c)(2)(B) to require such Serious and above areas to obtain 18 percent 

ozone precursor emission reductions in that 6 year period. Under the section 172(c)(2) and 

 

9 Hereafter in the discussion of RFP requirements within this section, when we use the term 

“2008 nonattainment area” we mean “nonattainment area classified as Moderate or higher under 

the 2008 ozone NAAQS.”

10 Similar interpretations were made for the 1997 8-hour ozone NAAQS Phase 2 Ozone 

Implementation Rule, (70 FR 71615, November 29, 2005) and were upheld in NRDC v. EPA, 

571 F.3d 1245 (D.C. Cir. 2009).
47

182(c)(2)(B) RFP requirements, NOx emission reductions could be substituted for VOC 

reductions. 

Comment: Do not support showing of 15 percent VOC reduction from 1990 

Commenter (0180) stated that, an area which may have by now (or by the time of SIP submittal) 

experienced a 15 percent cut in VOC emissions from the 1990 baseline cannot be deemed to 

satisfy the 15 percent reduction mandate in section 182(b)(1) because emission reductions are 

only creditable toward the 15 percent cut required in 1990 baseline emissions to the extent “they 

have actually occurred, as of 6 years after November 15, 1990. . .” 42 U.S.C. § 7511a(b)(1)(C). 

Commenter (0180) stated, reductions are only creditable if they have occurred “from the 

implementation of measures required under the applicable implementation plan, rules 

promulgated by the Administrator, or a permit under” Title V. Id. Commenter (0180) asserted 

that, option 2 does not satisfy the statutory requirements in section 182(b)(1). 

Response: The EPA has interpreted the requirements of subpart 2 as they would apply to 

nonattainment areas for the 1997 ozone NAAQS. We are now following the same interpretation 

with regard to the 2008 ozone NAAQS. With respect to RFP requirements, we interpret the 15 

percent VOC emission reduction requirement in section 182(b)(1) such that an area that has 

already met the 15 percent requirement for VOC under either the 1-hour ozone NAAQS or the 

1997 8-hour ozone NAAQS (for the first 6 years after the RFP baseline year for the 1-hour ozone 

NAAQS) would not have to fulfill that requirement again. Instead, such areas would be treated 

like areas covered under section 172(c)(2) if they are classified as Moderate for the 2008 

standard and would need to meet the RFP requirements under section 182(c)(2)(B) if they are 

classified as Serious or above for the 2008 ozone NAAQS.11 For the purposes of the 2008 ozone 

NAAQS, the EPA is interpreting section 172(c)(2) to require such Moderate areas to obtain 15 

percent ozone precursor emission reductions over the first 6 years after the baseline year for the 

2008 ozone NAAQS and is interpreting section 182(c)(2)(B) to require such Serious and above 

areas to obtain 18 percent ozone precursor emission reductions in that 6 year period. Under the 

section 172(c)(2) and 182(c)(2)(B) RFP requirements, NOx emission reductions could be 

substituted for VOC reductions. 

Comment: Generally support allowing use of NOx emission reductions

Commenters (0130, 0143, 0152, 0155, 0157, 0161, 0162, 0169, 0172, 0177, 0178 and 0179) 

generally supported the proposed provision allowing states to meet the RFP requirements using 

NOx emission reductions. Commenters (0130, 0143, 0160, 0161 and 0169) stated, this provision 

reflects the latest science showing that NOx emission reductions are more effective than VOC 

emission reductions in reducing ground level ozone concentrations. Commenters (0143, 0161) 

 

11 Similar interpretations were made for the 1997 8-hour ozone NAAQS Phase 2 Ozone 

Implementation Rule, (70 FR 71615, November 29, 2005) and were upheld in NRDC v. EPA, 

571 F.3d 1245 (D.C. Cir. 2009).
48

stated that, finding reductions in VOC emissions could be increasingly difficult to achieve in 

future years based on the current knowledge of VOC control technology and phase-in of current 

regulations. This being so, Commenter (0161) stated that, fulfilment of RFP requirements would 

be unnecessarily difficult if states were not allowed to substitute NOx reductions for VOC 

reductions.

Commenters (0143 and 0178) stated that, substituting NOx emission reductions for a portion of 

the needed VOC reductions is a practice that the EPA has approved in certain instances for the 

purposes of RFP SIP revisions and they supported the continued use of substituting NOx for 

VOC as appropriate in RFP plan analyses. To the extent that the EPA believes it has the legal 

authority to allow NOx reductions to substitute for VOC reductions for RFP, commenters (0155

and 0157) supported this approach. Commenter (0152) stated that, each state, based upon its 

analysis, should determine if NOx or VOC reductions are most beneficial towards achieving a 15 

percent RFP requirement and urged the EPA to reconsider the proposal requirements. 

Commenter (0152) stated that, a state should not be bound by a CAA requirement that is no 

longer applicable based upon current science that was intended to address a different standard at 

a different time and was developed when there was an entirely different inventory of emission 

sources to address. 

Commenters (0140, 0145 and 0160) agreed with the proposed alternative that would allow newly 

classified Moderate areas to substitute NOx for VOC in the 15 percent plans. Commenter (0140) 

stated that, restricting RFP emission reductions to VOC is not a reasonable interpretation of the 

statute for areas like Texas where ozone is NOx -limited and where ozone transport typically 

accounts for well more than half of an area’s ozone levels on high ozone days. Commenter 

(0145) stated these alternatives give nonattainment areas more flexibility in working towards 

attaining the ozone NAAQS, particularly those areas that have already achieved VOC reductions 

and need to obtain additional reductions. Commenter (0172) stated that, although the CAA 

requires RFP reductions to be VOC, the Commenter supports the substitution of NOx reductions 

for VOC in the 15 percent RFP SIP.

Commenter (0179) agreed with the EPA that, due to the success of VOC control measures over 

the past 20 years in certain areas of the U.S., future reductions in anthropogenic VOC may have 

little to no impact on ambient ozone levels. Commenter (0179) believed that addressing NOx

levels could have a greater impact on attainment of the ozone standard and will help carry out

Congress’ intent to reduce ozone levels while allowing for flexibility in applying section 182(b) 

and is a narrow yet feasible method of making RFP toward ozone attainment.

Response: The EPA appreciates the support of the Commenters. We are finalizing as proposed, 

such that 2008 nonattainment areas that have met the CAA requirement for a 15 percent ROP 

VOC reduction plan for the entire area are not required to fulfill that requirement again. This 

decision is consistent with the D.C. Circuit Court’s reasoning in NRDC v. EPA.12 In that case, 

 

12 See NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009),
49

concerning the EPA’s same interpretation for implementing the 1997 ozone NAAQS, the Court 

held that section 182(b)(1) is ambiguous and that it was reasonable for the EPA to interpret it not 

to require areas that had already met the 15 percent VOC emission reduction requirement to 

obtain another 15 percent reduction in VOC emissions. Instead, for purposes of the 1997 ozone 

NAAQS and for purposes of the 2008 ozone NAAQS, the EPA interprets the RFP requirement 

of section 172(c)(2) to require an area classified as Moderate to achieve an average 3 percent 

reduction in VOC and/or NOx per year for the first 6 years following the baseline year and the 

RFP requirement in section 182(c)(2)(B) to require the same thing for areas classified as Serious 

or higher. Thus, areas that had previously met the 15 percent VOC-only requirement under 

section 182(b)(1) are subject instead to provisions that allow NOx to substitute for VOC to 

satisfy the RFP requirements. 

Comment: Reservations about substituting NOx for VOC 

Commenters (0158, 0166 and 0174) expressed reservations about substituting NOx emission 

reductions for VOC reductions. Commenter (0166) stated, that for policy, economic and 

scientific reasons, the EPA should not place a higher overall priority on NOx reductions than 

VOC reductions to attain the ozone NAAQS. The Commenter added, that given that substantial 

reductions have been made in emissions of both VOC and NOx, decisions on whether to 

emphasize VOC or NOx controls now must be scientifically justified on a case-by-case basis. 

Commenter (0166) cited and attached a technical report, explaining the state of scientific 

understanding of the relative contributions of NOx and VOC to ozone formation and claimed 

there is no scientific basis for favoring NOx emission reductions over VOC reductions in 

nonattainment areas nationwide. The Commenter suggested that, decisions concerning whether 

to emphasize NOx or VOC controls must be made on an area-by-area basis. 

Commenter (0174) stated that, their biggest concern with the current proposed implementation 

plan is the assumption that the EPA makes that NOx emission reductions can be substituted for 

VOC emission requirements, mandated by the RFP portion of the rule. Commenter (0174) 

believed VOC emission reductions in many nonattainment areas will lead to greater progress 

reducing ground-level ozone at the critical ozone monitoring site(s) than NOx emission 

reductions. Commenter (0174) stated, detailed photochemical modeling analyses are needed to 

confirm which ozone precursor is more effective, prior to choosing an effective strategy to 

achieve this NAAQS, especially in and downwind of the urban core of many large metropolitan 

areas in the Midwest. 

Commenter (0158) questioned, whether the EPA has the authority under the CAA to allow NOx

reductions as a substitute for VOC reductions with respect to the initial 15 percent VOC RFP 

requirement in all areas where the requirement must be met for the first time. The commenter 

argued, that section 182(b)(1)(A) of the CAA specifically requires a 15 percent VOC reduction 

for Moderate and above nonattainment areas and does not make any provisions for any 

substitution of NOx reductions for these initial VOC RFP requirements. The CAA, under section 

182(c)(2)(C), allows only Serious and above nonattainment areas to substitute NOx reductions 

for required VOC reductions, but allows such substitution only for the 3 percent per year 

reductions required under section 182( c )(2)(B) after initial 15 percent VOC reduction is met. 

The Commenter further argued that the assertion that additional VOC reductions in 
50

nonattainment areas will be difficult to achieve and have little effect on further reducing ozone, 

given the variety of national and local VOC controls measures that have been imposed on mobile 

and stationary sources and have substantially reduced VOC emissions, does not properly 

recognize that significant NOx reductions have also been achieved throughout the country 

through both local-scale measures, such as RACT in nonattainment areas and regional programs 

such as the Acid Rain (Title IV) Program, the NOx SIP Call and Clean Air Interstate Rule 

(CAIR). Commenter (0158) believed that, to the extent the EPA does allow NOx for VOC 

substitutions for meeting the initial 15 percent RFP requirement, it should only be allowed on a 

case-by-case basis with a technical demonstration from the state that such a substitution is 

scientifically justified.

Response: The EPA agrees that today’s understanding of the role of NOx reductions would 

suggest that, in some areas, it would be relatively more efficient to focus attainment planning 

efforts on achieving reductions in NOx rather than VOC emissions. However, the CAA section 

182(b)(1) expressly requires the 15 percent ROP plans to reduce emissions of VOC. It does not 

provide discretion to meet these requirements by reducing emissions of other pollutants. Where 

Congress intended to allow such a substitution, it specifically provided so, such as in section 

182(c)(2)(C) which allows NOx to be substituted for VOC in the 3 percent annual RFP plans for 

Serious and above areas.

We are finalizing as proposed, such that 2008 nonattainment areas that have met the CAA 

requirement for a 15 percent ROP VOC reduction plan for the entire area are not required to 

fulfill that requirement again. This decision is consistent with the D.C. Circuit Court’s reasoning 

in NRDC v. EPA.13 In that case, concerning the EPA’s same interpretation for implementing the 

1997 ozone NAAQS. the Court held that section 182(b)(1) is ambiguous and that it was 

reasonable for the EPA to interpret it not to require areas that had already met the 15 percent 

VOC emission reduction requirement to obtain another 15 percent reduction in VOC emissions. 

Instead, for purposes of the 1997 ozone NAAQS and for purposed of the 2008 ozone NAAQS, 

the EPA interprets the RFP requirement of section 172(c)(2) to require an area classified as 

Moderate to achieve an average 3 percent reduction in VOC and/or NOx for the first 6 years 

following the baseline year and the RFP requirement in section 182(c)(2)(B) to require the same 

thing for areas classified as Serious or higher. Thus, areas that had previously met the 15 percent 

VOC-only requirement under section 182(b)(1) are subject instead to provisions that allow NOx

to substitute for VOC to satisfy the RFP requirements. As explained in the proposal, we believe 

there are two policy reasons for interpreting this ambiguous provision in this manner. First, both 

our understanding of the effects of reductions of VOC and NOx on ambient ozone levels and the 

technical tools to help predict what combinations of reductions of ozone precursors will be most 

effective in ozone reduction have improved. Since the purpose of the RFP provisions in sections 

172 and 182 is to foster the achievement of RFP toward attainment, we believe that it makes the 

most sense to allow states to credit toward the RFP requirement those reductions that an area 

most needs to reach attainment. Second, as explained more fully in the proposal, the mix of 

 

13 See NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009),
51

emissions across the country and in specific areas is very different than it was in 1990 because of 

various measures and developments that have substantially reduced the anthropogenic VOC 

emissions inventory such that additional area-specific VOC reductions will be increasingly 

difficult to achieve. 

Comment: NOx substitution in the OTR

Commenter (0159) did not support the third option, as the Baton Rouge Area is not located 

within the OTR, which means that the implementation of this proposal would result in the Area 

being unable to participate in this portion of the SIP Requirements Rule. Commenter (0161) 

objected to the EPA’s proposal to finalize a rule that would allow NOx substitution only in 

nonattainment areas that are located in the Ozone Transport Region (OTR) and that would be 

subject to the 15 percent RFP requirement for the first time based on a nonattainment designation 

for the 2008 ozone NAAQS. Commenter (0161) asserted that, the preamble fails to articulate any 

reasonable basis upon which to allow only a subset of nonattainment areas to substitute NOx

reductions for VOC reductions and that none exists. Commenter (0161) believed all 

nonattainment areas should be allowed to take advantage of this alternative, not just a few 

nonattainment areas in the northeastern part of the U.S. 

Response: The EPA has reconsidered its proposal and now believes it does not have authority 

under the CAA to allow NOx substitution for VOC emissions reductions for the 15 percent ROP 

in any area, including an area located in the OTR. Therefore, the EPA is not finalizing as 

proposed the flexibility to allow areas in the OTR to substitute NOx for VOC to meet the 15 

percent ROP requirement. 

Comment: Do not support allowing NOx substitution

Commenters (0163, 0166, 0168 and 0180) stated that, section 182(b)(1) does not allow 

substitution of NOx reductions for VOC reductions to meet the 15 percent requirement. 

Commenter (0163) stated, new Moderate nonattainment areas must meet this CAA requirement 

and, therefore, are subject to the 15 percent VOC RFP requirement from the time the area is 

subject to this section of the CAA. Commenter (0166) stated that, section 182(b)(1)(A) of the 

CAA requires Moderate (and higher) nonattainment areas to submit a SIP revision that requires 

reduction of VOC emissions by 15 percent and does not allow any NOx emission reductions to 

be substituted for the required VOC emission reductions. That provision requires a state with a 

Moderate or higher nonattainment area to: submit a [SIP revision] to provide for VOC emission 

reductions . . . of at least 15 percent from baseline emissions . . . . Such plan shall provide for 

such specific annual reductions in emissions of VOC and oxides of nitrogen as necessary to 

attain the national primary ambient air quality standard for ozone by the attainment date 

applicable under this Act. (Emphasis added.) The Commenter added that, under section 

182(c)(2)(C), the Act allows substitution of NOx emission reductions for required VOC 

reductions only for the 3 percent per year reductions required under section 182(c)(2)(B) after 

the 15 percent RFP demonstration required by section 182(b)(1). Because the EPA has failed to 

demonstrate it has discretion to allow for substitution of NOx emission reductions for the 15 

percent reduction of VOC emissions in an area that has never adopted and implemented a SIP 

providing for such VOC emission reductions, UARG urged the EPA to adopt “Alternative 1” 
52

under its proposed 40 CFR § 51.1110(b). Alternative 1 mandates that nonattainment areas 

classified as Moderate or above that have yet to satisfy the requirement for a plan to reduce VOC 

emissions by 15 percent adopt a plan providing for such reduction of VOC emissions to 

demonstrate RFP toward attaining the ozone NAAQS. The Commenter pointed out that, in 

NRDC v. EPA, however, the D.C. Circuit did not hold – and nothing in that decision implies –

that an area that had never adopted or implemented a 15 percent VOC emission reduction SIP 

provision may avoid the statutory requirement for such a SIP provision. Thus, nothing the D.C. 

Circuit said in that case supports substitution of NOx emission reduction for VOC emission 

reduction in an area for which the state never adopted or implemented a SIP provision that 

required a 15 percent reduction in VOC emission. The Commenter stated that, if the EPA 

nevertheless adopts a NOx-for-VOC substitution approach for areas without an existing plan for 

reducing VOC emissions by 15 percent, there is no basis for only one part of the country – the 

OTR – being granted the NOx-for-VOC substitution option for the initial 15 percent VOC 

reductions while denying the rest of the country the option. The EPA has not adequately 

explained why there is any greater legal or policy justification for allowing NOx emission 

reductions to satisfy the 15 percent VOC emission reduction requirement under section 182(b)(1) 

in the OTR as opposed to the rest of the country. Furthermore, if the EPA does adopt the option 

only for the OTR, any expansion of the OTR should not result in NOx-for-VOC substitutions in 

new areas unless the rest of the country is similarly granted the option. 

Commenter (0168) did not support substitution of NOx reductions for VOC reductions in 

15 percent RFP plans. Commenter believes that, RFP must be calculated and complied with as a 

percentage of base year inventory emissions, which is consistent with the plain reading of the 

CAA and with prior EPA interpretations and has resulted in the necessary control of both VOC 

and NOx emissions in the covered areas.

Commenter (0180) stated that, the first option is the only option permissible under the statute. 

The Commenter added that, the mandate for a 15 percent VOC cut hardly prevents the EPA or a 

state from requiring NOx cuts in addition to the VOC reductions. The Commenter further stated 

that, even if the EPA could lawfully allow substitution of NOx reductions for the VOC reductions 

required by section 182(b)(1), the EPA cannot lawfully or rationally allow such substitution in 

areas where the EPA has granted NOx waivers under subsection 182(f) or otherwise limited the 

requirements for NOx control under that subsection. 

Response: The CAA section 182(b)(1) expressly requires the 15 percent ROP plans to reduce 

emissions of VOC. It does not provide discretion to meet these requirements by reducing 

emissions of other pollutant precursors. Where Congress intended to allow such a substitution, it 

specifically provided so, such as in section 182(c)(2)(C) which allows NOx to be substituted for 

VOC in the 3 percent annual RFP plans for Serious and above areas. Also, for nonattainment 

areas that have met the CAA requirement for a 15 percent ROP VOC reduction plan for the 

entire area are not required to fulfill that requirement again. Instead, for purposes of the 1997 

ozone NAAQS and for purposed of the 2008 ozone NAAQS, the EPA interprets the RFP 

requirement of section 172(c)(2) to require an area classified as Moderate to achieve an average 

3 percent reduction in VOC and/or NOx for the first 6 years following the baseline year and the 

RFP requirement in section 182(c)(2)(B) to require the same thing for areas classified as Serious 
53

or higher. Thus, areas that had previously met the 15 percent VOC-only requirement under 

section 182(b)(1) are subject instead to provisions that allow NOx to substitute for VOC to 

satisfy the RFP requirements.

Comment: EPA should develop information regarding when NOx emission reductions can 

be substituted for VOC reductions 

Commenter (0166) stated that, although it may make sense in certain areas (to the extent that 

substitution of NOx reductions for VOC reductions is legally permissible) to allow states to 

require greater NOx reductions than VOC reductions, there is insufficient data on these issues 

available for states to make informed decisions about when NOx emission reductions would 

justifiably be substituted for VOC emission reduction requirements. The commenter urged the 

EPA to develop the necessary information that may allow for better NOx-versus-VOC 

comparisons and decision-making.

Response: The EPA has already developed the information requested by the commenter. The 

EPA developed the NOx Substitution Guidance, December 1993, that provides a procedure that 

can be applied to meet the section 182(c)(2)(B) RFP requirement as well as the section 

182(c)(2)(C) equivalency demonstration requirements. This guidance is intended to facilitate 

implementation of the most effective ozone precursor control strategies, while meeting the intent 

of the CAA RFP provisions. This document can be accessed at the following web address: 

http://www.epa.gov/ttn/caaa/t1/memoranda/noxsubst.pdf. The EPA, on August 5, 1994, issued a 

memorandum titled, Clarification of Policy for NOx Substitution, John S. Seitz, Director, Office 

of Air Quality Planning and Standards, which issues a clarification on NOx substitution for ROP 

plans, specifically, what the EPA will accept as evidence that NOx substitution for VOC 

reductions is a viable approach. This memorandum can be accessed at the following web 

address: http://www.epa.gov/ttn/caaa/t1/memoranda/clarisub.pdf.

Comment: Disagree with 15 Percent RFP Requirement

Commenter (0152) stated that, a 15 percent RFP requirement is outdated and not necessitated 

under the current ozone standard using recent baselines. The Commenter added that meeting a 15 

percent RFP requirement can be a difficult challenge. The 1990 CAA Amendments required RFP 

to address the 1-hour ozone standard at a time when the baseline was significantly higher and 

there were more cost effective reductions available. Even then it was a challenge to show where 

RFP could occur, but today it would be even more challenging because significant reductions in 

VOC, and NOx, have occurred since the 1990 CAA Amendments. 
54

Response: The EPA disagrees. The regulation must comply with the CAA. Section 182(b)(1) of 

the CAA explicitly requires that ozone nonattainment areas classified as Moderate or higher 

submit a ROP plan to achieve a 15 percent reduction in VOC baseline emissions over a 6-year 

period following the baseline year.

2. 2008 ozone nonattainment areas which previously met the 15 percent RFP requirement 

for VOC 

Comment: New 15 percent VOC plan not required

Commenters (0145, 0146, 0151, 0158, 0159, 0160, 0163, 0166, 0169 and 0179) agreed with the 

EPA’s proposal that 2008 nonattainment areas that have already met the CAA requirement for a 

15 percent VOC reduction plan are not required to fulfill that requirement again. Commenters 

(0146, 0151 and 0166) agreed that, this is a reasonable approach and that it is consistent with the 

decision in NRDC v. EPA, 571 F.3d 1235 (D.C. Cir. 2009). 

Commenter (0151) stated, the proposed approach will reduce the burden on state agencies in the 

next rounds of SIP planning and that Congress did not intend the 1990 Amendments to the Act to 

create repetitive implementation of the same requirements that Congress listed in 1990 to ensure 

state and the EPA actions took place for ozone reduction. The Commenter added that, evidence 

in the record recounts that during discussion of adoption of these measures, members of 

Congress simply doubted the ability of the EPA and/or the states to prescribe the measures that 

would be capable of bringing ozone values down in the country. Therefore, just as it did with 

implementation of the hazardous air pollutant (HAP) program, the Congress prescribed the 

measures that would be required for the next round of ozone SIP revisions. In contrast to the 

HAP program, however, here is no further evidence that Congress meant for the 15 percent RFP 

or the 3 percent ROP requirements to re-apply every time that the ozone standard was revised. In 

fact, once a state has obtained approval of its 15 percent RFP (and ROP plan if in an area with a 

worse ozone issue), Congress thought that most areas of the country would attain the ozone 

standard. This makes it even less likely that members of Congress intended the states to have to 

adopt another 15percent RFP plan for reducing stationary source emissions. Moreover, it is 

unlikely that after a round of RACT and RFP for most areas once designated nonattainment for 

the ozone NAAQS, further reductions of ozone precursors would be available on this scale. 

Commenter (0163) state, the pertinent requirement of the CAA is to reduce VOC by 15 percent 

in an area once it is subject to this section of the CAA. If a state has already produced a 15 

percent RFP plan for VOC, it has met the CAA obligation and can be allowed to substitute NOx

for the 15 percent RFP requirement for the 2008 ozone NAAQS. Commenter (0180) supported 

the EPA’s proposal (78 FR at 34189/1) to require, for Moderate areas that previously met the 15 

percent VOC reduction requirements in section 182(b)(1), an additional 15 percent emission 

reduction in VOC and/or NOx in Moderate and above areas to meet the ROP requirement in 

section 172(c)(2). 

Response: The EPA acknowledges that 15 percent VOC reductions are required for all Moderate 

and above areas, but we continue to maintain that if a state has submitted, adopted and 

implemented its nonattainment area ROP/RFP emissions reduction plan to meet the requirements 
55

of section 182(b)(1)(A) for either the 1-hour standard or the 1997 8-hour standard, they will not 

have to meet it again for the 2008 ozone NAAQS. The EPA believes the CAA is quite clear that 

the SIP must provide for a 15 percent reduction in baseline VOC emissions within 6 years of the 

baseline inventory year for some period after 1990 in an area subject to 182(b)(1)(A). It is the 

EPA’s position that states must only submit ROP SIPs if the EPA has not already approved a 

state’s 1-hour or 1997 ozone SIP ROP Plan. We believe that this is consistent with the decision 

in NRDC v. EPA, 571 F.3d 1235 (D.C. Cir. 2009), and this policy will reduce the burden on state 

agencies in SIP-planning for the 2008 ozone NAAQS. We believe Congress did not intend the 

1990 Amendments to the Act to create repetitive implementation of the same requirements that 

Congress listed in 1990 to ensure state and EPA actions took place for ozone reduction. The EPA 

believes that the CAA plainly does not require that a second ROP SIP providing for 15 percent 

reduction in VOC baseline emissions under a revised ozone standard. Instead, for purposes of the 

1997 ozone NAAQS and for purposed of the 2008 ozone NAAQS, the EPA interprets the RFP 

requirement of section 172(c)(2) to require an area classified as Moderate to achieve an average 

3 percent reduction in VOC and/or NOx for the first 6 years following the baseline year and the 

RFP requirement in section 182(c)(2)(B) to require the same thing for areas classified as Serious 

or higher. Thus, areas that had previously met the 15 percent VOC-only requirement under 

section 182(b)(1) are subject instead to provisions that allow NOx to substitute for VOC to 

satisfy the RFP requirements.

Comment: Disagree with the EPA’s two proposed approaches

Commenter (0152) stated that, treating the entire area as if no RFP requirement had applied was 

nonsensical and without basis and that RFP should only occur from the 1990 baseline in all 

circumstances and only a 15 percent requirement should be applicable over a 6-year period.

Response: The EPA believes that states must only submit RFP SIPs if the EPA has not already 

approved a state’s ROP/RFP Plan. The EPA believes that the CAA plainly does not require that a 

second ROP SIP providing for 15 percent reduction in VOC baseline emissions within 6 years of 

the baseline inventory year under a revised ozone standard.

Comment: Require an additional 15 percent VOC plan

Commenter (0180) stated that, although the Court in NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 

2009), held the EPA could permissibly read the statute as requiring SIPs to provide for the 15 

percent VOC reduction only once, the Court did not address the question of whether mere EPA 

approval of a prior 15 percent ROP SIP would satisfy the 15 percent requirement for a 

subsequent NAAQS, or whether the area would have to show it actually achieved the 15 percent 

VOC reduction within the 6 years required by the statute. Commenter (0180) asserted that, to be 

creditable, the 15 percent reduction must have actually occurred within 6 years of November 15, 

1990 due to implementation of measures required under the SIP, rules promulgated by the EPA, 

or Title V permits. Accordingly, Commenter (0180) believed, the EPA cannot treat previously 

approved ROP plans as satisfying the 15 percent ROP requirement unless the state also shows 

that the required VOC reductions were actually achieved as required by section 182(b)(1)(C). 
56

Response: The EPA disagrees with the Commenter. We have maintained in the 1997 8-hour 

ozone NAAQS implementation rule and in the proposed 2008 NAAQS SIP requirements rule 

that if a state has already submitted, adopted and implemented its 15 percent ROP/RFP plan for 

an area to reduce VOC emissions for the either the 1-hour standard or the 1997 8-hour standard, 

the state should not be required to meet that requirement a second time for that area for the 2008 

ozone NAAQS but instead the area will be subject to the other applicable RFP provisions of the 

CAA.

Comment: Support using NOx emission reductions in areas that have already satisfied the 

15 percent VOC reduction requirement

Commenters (0139, 0150 and 0163) supported the EPA’s proposal to allow areas that have 

already satisfied the 15 percent VOC reduction requirement of the CAA section 182(b)(1) to use 

NOx reductions in lieu of VOC (78 FR 34178, 34187 col. 2). These Commenters stated that, in 

many areas, NOx reductions are far more effective than VOC reductions in making progress 

toward attainment and NOx substitution is a logical means of achieving the purposes of the RFP 

requirement which is to ensure steady progress towards the goal, since it will provide more 

progress than would relying on VOC reductions. Commenters (0139 and 0150) stated that, given 

the advancement in scientific knowledge since the 1990 Amendments demonstrating that in 

many areas NOx reductions are far more effective than VOC reductions, the EPA may 

reasonably conclude that the requirement for VOC RFP reductions need only be met once, and 

any remaining RFP requirements may be set as the Administrator may reasonably require, as 

under Subpart 1 (CAA §172(c)(2); CAA §171(1)-definition of RFP). Commenter (0139) stated, 

the EPA has the ability to authorize the use of equivalent planning procedures under §172(c)(8); 

therefore, the EPA may reasonably interpret the RFP requirements to allow such substitution. 

Commenter (0150) added that, some may argue that NOx substitution may only be used for RFP 

requirements beyond the first 6 years, as referred to in CAA §§ 182 (c)(2)(B) and (c)(2)(C). 

However, this position ignores the fact that the EPA proposes to allow NOx substitution for the 

first 15 percent RFP requirement only for those areas that have already satisfied that requirement 

in an earlier approved ozone plan. The EPA is not required to apply each and every requirement 

of Subpart 2 according to a literal application of its terms. The U.S. Supreme Court held that the 

CAA is ambiguous as to the interaction between Subpart 1 and Subpart 2 with regard to a revised 

ozone standard and explained that it would defer to the EPA's reasonable resolution of the 

ambiguity. Whitman v. American Trucking Ass 'ns, 531 U.S. 457, 484 (2001). The Court noted 

that some parts of Subpart 2 may be ill-suited to implementing the revised standards, such as the 

statutory attainment deadlines and would require some interpretation.

Response: In previous responses, we have stated that, if a state has already submitted, adopted 

and implemented its 15 percent ROP/RFP plan to reduce VOC emissions in a nonattainment area

for either the 1-hour standard or the 1997 8-hour standard, the area should not be required to 

meet that requirement a second time for the 2008 ozone NAAQS. Instead, such areas would be 

treated like areas covered under section 172(c)(2) if they are classified as Moderate for the 2008 

standard and would need to meet the RFP requirements under section 182(c)(2)(B) if they are 
57

classified as Serious or above for the 2008 ozone NAAQS.14 For the purposes of the 2008 ozone 

NAAQS, the EPA is interpreting section 172(c)(2) to require such Moderate areas to obtain 15 

percent ozone precursor emission reductions over the first 6 years after the baseline year for the 

2008 ozone NAAQS and is interpreting section 182(c)(2)(B) to require such Serious and above 

areas to obtain 18 percent ozone precursor emission reductions in that 6 year period. Under the 

section 172(c)(2) and 182(c)(2)(B) RFP requirements, NOx emission reductions could be 

substituted for VOC reductions.

2. 2008 ozone nonattainment areas where portions have a previously approved 15 percent 

VOC reduction plan

Comment: Support the proposed approaches

Commenter (0163) stated that, if a nonattainment area is expanded to include new jurisdictions, 

the RFP plan for this area must include either a separate 15 percent VOC reduction for the new 

jurisdictions or a reduction equal to that separate 15 percent VOC requirement from the entire 

nonattainment area. The Commenter added that, the requirement to reduce VOC emissions 

cannot be eliminated in its entirety except as provided for in CAA section 182(b)(l)(A)(ii). 

Response: The Commenter is correct to recognize that, the EPA cannot simply eliminate the 15 

percent emission VOC reduction requirement of section 182(b)(1). We have already stated that 

for nonattainment areas with an approved 15 percent ROP/RFP plan for a previous ozone 

standard, a state will not be required to submit, adopt and implement a second 15 percent plan 

under section 182(b)(1) for purposes of the 2008 ozone NAAQS. 

Comment: Do not support the second proposed approach

Commenter (0180) stated that, the second option is not permissible under the Act. Commenter 

(0180) stated that, a prior 15 percent plan for just part of the 2008 nonattainment area cannot be 

deemed to satisfy the 15 percent requirement for the 2008 nonattainment area, because that 

“area” is different from the area encompassed by the prior 15 percent plan. Commenter (0180) 

asserted that the prior plan could not have purported to provide for a 15 percent cut from baseline 

emissions in an “area” that was not even defined at the time of the prior plan, nor does the statute 

allow for dividing up “the area” into multiple sub-areas with separate 15 percent ROP plans or 

requirements. Commenter (0180) stated, the statute requires the SIP to calculate the total amount 

of actual VOC emissions from all sources in “the area” – meaning the nonattainment area (not 

just some portion thereof) – and provide for a 15 percent reduction from that total baseline. 

Commenter (0180) stated that, even if option 2 was otherwise permissible (which it is not), it 

 

14 Similar interpretations were made for the 1997 8-hour ozone NAAQS Phase 2 Ozone 

Implementation Rule, (70 FR 71615, November 29, 2005) and were upheld in NRDC v. EPA, 

571 F.3d 1245 (D.C. Cir. 2009).
58

would be illegal and arbitrary to let the sub-area claim credit for emission reductions from 

outside the sub-area without having to also add emissions from outside the sub-area to its 

baseline. Commenter (0180) stated that, unless the EPA is proposing to require that the nonformer ROP sub-area assure a net 15 percent cut from new baseline emissions for the entire 2008 

nonattainment area, it cannot – consistent with section 182(b)(1) – allow the sub-area to claim 

credit for reductions outside the sub-area. Commenter (0180) asserted that, if the EPA is going to 

create sub-areas within the nonattainment area, each with its own 15 percent reduction 

obligation, then the required VOC emission reductions must come from inside each sub-area 

respectively. See NRDC, 571 F.3d at 1257 (statutory mandate for reductions “in the area” 

requires “that any reductions emissions derive from reductions at sources within a particular 

area”). 

Further, Commenter (0180) stated that, although NRDC held that the EPA could read the statute 

as requiring a SIP to provide for the 15 percent VOC reduction only once, option 2 does not 

assure such a result as there is no assurance that the entire 2008 nonattainment area will in fact 

achieve a total 15 percent VOC emissions cut either from a 1990 baseline or a 2011 baseline for 

the whole area. Commenter (0180) concluded that, the EPA offers no rationale for how its 

proposed option 2 approach is consistent with the Act or advances its purposes. 
59

Response: We agree with the commenter that the first option, to treat the entire 2008 

nonattainment area as having never met the 15 percent requirement, is permissible under the 

CAA. However, we disagree with the commenter’s assertion that the second option, to treat a 

portion of the 2008 nonattainment area as having met the 15 percent requirement, and a portion 

as still needing a 15 percent plan is not allowable. We believe that the portion of a nonattainment 

area that has a previously approved 15 percent ROP plan has satisfied the ROP requirement for 

that area and we have maintained that areas or portions of areas that have already met the 15 

percent VOC emission reduction requirement for a previous ozone standard are not required by 

the CAA to meet that requirement a second time for the 2008 ozone NAAQS. 

The EPA recognizes that the new portions of the nonattainment area that have not met the 15 

percent VOC emission reduction requirement are subject to section 182(b)(1). We disagree with 

the Commenter that a prior approved 15 percent plan for just part of the new 2008 nonattainment 

area cannot be deemed to satisfy the 15 percent requirement for the 2008 nonattainment area 

simply because that area is different from the area encompassed by the prior 15 percent plan. The 

final rule offers states two options for addressing the 15 percent ROP requirement. First, the state 

could choose to treat the entire area as an area that never met the 15 percent requirement and 

meet the requirements as described in the final rule. Second, the state could choose to treat the 

2008 nonattainment area as divided into two portions: the former non-ROP plan portion and the 

former ROP plan portion. For the former non-ROP plan portion of the 2008 nonattainment area, 

the plan would establish a separate 15 percent VOC reduction requirement under section 

182(b)(1). However, it is important to recognize that VOC emissions reductions to meet the 15 

percent requirement must come from within the boundaries of the non-ROP plan portion. 

Additionally, the ROP plan for the 2008 ozone NAAQS for the new non-ROP plan portion 

remains responsible for achieving the 15 percent VOC reductions. 

The second option in the final rule differs from the second approach described in the proposed 

rule in that we make it clear that the approved RFP plan portion cannot entirely provide for a 15 

percent reduction from baseline emissions in the entire area. We believe that the CAA provides 

the EPA with the authority to define ROP plan areas and non-RFP plan areas if the new non-RFP 

areas become subject to section 182(b)(1) and the 15 percent emission reduction credits come 

from within the non-RFP section.

Comment: Clarification needed for the second proposed approach

Commenter (0132) requested clarification concerning the VOC reduction target stipulation for 

the existing counties: The Commenter asked, if states would be allowed to set a VOC target for 

existing counties that is not reduced from the base year VOC target? In this case, there would be 

a "VOC target" for the existing counties, but no further VOC reductions would be required, and 

the 15 percent reduction requirement for those counties could be demonstrated with NOx

reductions only. Alternately, would states choosing to use VOC emission reductions from the 

entire 2008 nonattainment area to satisfy the newly designated portion's initial 15 percent VOC 

reduction requirement be required to then demonstrate an additional VOC reduction for the 

existing portion's 15 percent NOx and/or VOC reduction requirement, beyond the base year VOC 

target? Please clarify whether the language describing the second approach in Section III.C.2.e of 

the proposal is meant to be read as either of the above interpretations, or if the EPA intended a 
60

completely different interpretation.

Response: In consideration of nonattainment areas that include portions consisting of all or a 

piece of one or more nonattainment areas for a previous NAAQS and which achieved their ROP 

plan to reduce VOC by 15 percent combined with portions that have never been subject to or 

have not fulfilled the 15 percent ROP plan requirements, the EPA has reevaluated the proposed 

second approach that allows states to choose to use VOC emission reductions from a designated 

2008 nonattainment area that can demonstrate 15 percent ROP VOC emission reductions 

previously achieved in an older portion of the nonattainment area to satisfy the newly designated 

portion's initial 15 percent VOC reduction requirement. In consideration of the comments 

received, the EPA has concluded that the approach should be modified. The EPA recognizes that 

the new portions of the nonattainment area that have not met the 15 percent VOC emission 

reduction requirement should be subject to section 182(b)(1). We find merit with the 

commenter’s suggestion where they argued that prior approved 15 percent ROP plans for a 

previous nonattainment area cannot be applied to the new 2008 nonattainment area and cannot be 

deemed to satisfy the 15 percent requirement for the 2008 nonattainment area in cases where the 

entire area is different from the area encompassed by the prior 15 percent plan. 

The final rule offers states two approaches for addressing the 15 percent RFP requirement. First, 

the state could choose to treat the entire area as an area that never met the 15 percent requirement 

and meet the requirements as described in the final rule. Second, the state could choose to treat 

the 2008 nonattainment area as divided into two portions: the former non-RFP plan portion and 

the former RFP plan portion. For the former non-RFP plan portion of the 2008 nonattainment 

area, the plan would establish a separate 15 percent VOC reduction requirement under section 

182(b)(1). However, it is important to recognize that VOC emissions reductions to meet the 15 

percent requirement must come from within the boundaries of the non-RFP plan portion. 

Additionally, if a portion(s) of the nonattainment area was not subject to an approved 15 percent 

plan for either the 8-hour standard or the 1-hour standard, referred to as a non-RFP plan portion, 

then section 182(b)(1) applies to that non-RFP plan portion(s) of the 2008 ozone nonattainment 

area and the initial ROP requirements may be met by achieving 15 percent VOC reductions.

The second option in the final rule differs from the second approach described in the proposed 

rule in that we make it clear that the approved RFP plan portion cannot entirely provide for a 15 

percent reduction from baseline emissions in the entire area. We believe that the CAA provides 

the EPA with the authority to define RFP plan areas and non-RFP plan areas if the new non-RFP 

areas become subject to section 182(b)(1) and the 15 percent emission reduction credits come 

from within the non-RFP section.

Comment: Serious and above areas

Commenters (0139, 0155 and 0157) supported the RFP requirements as proposed in the 40 CFR 

51.1110, which comports with CAA section 182(c)(2)(B). The commenter added that, for the 

1997 standard, 40 CFR 51.910(a)(1)(ii)(B) went beyond the authority of the CAA and required 

nonattainment areas classified Serious and above to get 18 percent reductions during the first 6 

years rather than 15 percent and also required Serious and above areas to submit RFP SIPs for 

the period after the first 6 years in 3 years after designation, rather than the 4 years allowed by 
61

the CAA. Unfortunately, the preamble language in the proposed rule (78 FR 34189 col. 1) 

confuses the matter by sounding like the EPA might be proposing requirements similar to those 

for the 1997 standard. CAPCOA strongly supports the EPA’s proposed CFR regulatory 

language, which comports with the CAA section 182(c)(2)(B). RFP requirements beyond those 

in section 182(c)(2)(B) are not authorized by the CAA for areas classified Serious and above.

Response: The final rule allows submission of the RFP plan up to 4 years from the date of 

designation. We do not believe the RFP provisions of subpart 2 of the CAA provide relief from 

the requirement to obtain the specified percent reductions from the RFP baseline within the time 

frame specified in those provisions.

Comment: RFP in expanded (old) nonattainment areas

Commenter (0151) stated that, it does not support either alternative because it believes that the 

15 percent VOC RFP requirement applied only once after adoption of the 1990 CAA 

Amendments and that the Congress did not intend for a state to adopt a new RFP plan either 

when the ozone standard is revised or when a state expands an ozone area for an existing or a 

revised standard, once the EPA approved the initial RFP. The commenter urged, the EPA to

require a state only to demonstrate that the major sources will be subject to RACT and that other 

federal and state controls on other sources, including unconventional, minor and mobile sources 

will result in progress (i.e., obtains reductions in excess of the already approved RFP 

demonstration.). If any RFP demonstration is required for expanded nonattainment areas,” the 

EPA only should require a state to demonstrate that “additional reductions” have been made 

beyond the original 15 percent RFP and major sources in these areas meet RACT. 

Commenter (0169) stated the EPA should use its discretionary authority to provide states with 

deference when determining how to treat new nonattainment areas which encompass old 

nonattainment areas, as each area is unique in its needs and potential for reductions. Commenter 

(0169) provided the following additional points. The Commenter stated they appreciate the 

EPA's attempt at addressing various scenarios to make the SIP Requirements Rule as useful to 

states as practicable. The commenter, however, believes the EPA should use its discretionary 

authority to provide states with deference when determining how to treat new nonattainment 

areas which encompass old nonattainment areas, as each area is unique in its needs and potential 

for reductions. The Commenter believes that, the provisions spelled out in Section 111.C.2.e of 

the SIP Requirements Rule will not only impact RFPs but also emission inventory reporting, 

emissions statements, transportation conformity, etc. As such, the commenter would like to 

applaud the EPA for its efforts, but caution the EPA to fully consider the ramifications of the 

proposed provisions. (0169)

Response: It is the EPA’s position that if a portion of a nonattainment area for the 2008 NAAQS 

was not subject to an approved 15 percent plan for either the 1-hour or the 1997 NAAQS, then 

section 182(b)(1) applies to that portion of the 2008 NAAQS area and may be met by one of two 

approaches described in the rule, which are as follows: The state could choose to treat the entire 

area as an area that never met the 15 percent requirement, or the state could choose to treat the 

2008 nonattainment area as divided into two portions: the former non-RFP plan portion and the 

former RFP plan portion. For the former non-RFP plan portion of the 2008 nonattainment area, 
62

the plan would establish a separate 15 percent VOC reduction requirement under section 

182(b)(1) of subpart 2. However, VOC emissions reductions to meet the 15 percent requirement 

may come from source located anywhere within the 2008 nonattainment area, provided that the 

former RFP plan portion of the area also achieves its separate VOC reduction target as part of its 

RFP plan for the 2008 ozone NAAQS. If the RFP plan for the 2008 ozone NAAQS for the 

former nonattainment area relies solely on NOx reductions, then the portion of the nonattainment 

area never before subject to nonattainment requirements must still achieve the required 15 

percent VOC reductions. 

The EPA disagrees with the Commenter that, the 15 percent VOC RFP requirement should only 

be applied once and that a state should not need to adopt a new RFP plan when a NAAQS has 

been revised or when a state expands an ozone area. The EPA does not believe the statute 

authorizes an area that has not already met the 15 percent requirement for the 1-hour or the 1997 

standard to be exempt from that obligation, except as provided in section 182(b)(1)(A)(ii), which 

specifies the circumstances under which a percentage of less than 15 may be used for purposes of 

meeting the RFP requirements. The EPA followed a similar approach in the preamble and 

regulatory text for the final Phase 2 Implementation Rule for the 1997 NAAQS (70 FR 71612, 

November 29, 2005). Based on this reasoning, the EPA also disagrees with the Commenter that a 

state should only be required to demonstrate that “Additional Reductions” have been made 

beyond the original 15 percent RFP and that major sources in these areas meet RACT. 

Additionally, the EPA notes that RACT requirements apply to sources in the entire 

nonattainment area, not solely one portion. Therefore, in cases where the nonattainment area for 

the 2008 NAAQS covers a geographic area that is larger than that of a previous NAAQS, states 

would need to conduct a RACT analysis that evaluates all sources in the 2008 NAAQS 

nonattainment area.

Lastly, the EPA appreciates the comment regarding the fact that each nonattainment area is 

unique and has its own needs for reductions. The EPA will review all SIP submissions on a caseby-case basis to evaluate the extent to which CAA requirements have been met. 

3. Non-creditable reduction calculations

Comment: Support removing the calculation requirement

Commenters (0130, 0141, 0152, 0153, 0155, 0157, 0159, 0160, 0163, 0169, 0175 and 0179) 

supported the proposal to remove the requirement of performing non-creditable reduction 

calculations. Commenters stated that, these calculations are tedious and burdensome (0130, 

0155, 0175, 0177 and 0179), they add no environmental benefit to the planning process (0130), 

with fleet turnover, such emission reductions are de minimis for SIP planning purposes (0160), 

and removing the requirement will streamline the RFP process somewhat and make the process 

easier to explain to interested parties such as section 174 planning organization participants. 

Commenter (0177) stated that, the pre-1990 calculation will be necessary if the EPA decides to 

allow states submitting a first-time 15 percent RFP Plan to substitute NOx for VOC reductions. 

According to the Commenter, the EPA indicated in the preamble (78 FR 34188) that states with 

such nonattainment areas must first demonstrate that a 15 percent VOC reduction was achieved 
63

relative to a 1990 baseline. The Commenter indicated that since those nonattainment areas would 

be required to look back to a 1990 baseline, the emission reductions from pre-1990 control 

measures are not likely to be de minimis, so they would need to be considered. 

Response: The EPA appreciates the Commenters’ support in removing the requirement to 

perform non-creditable reduction calculations. The final rule does not include a requirement to 

perform non-creditable reduction calculations.

Comment: Clarification needed for non-creditable reduction calculations

Commenter (0132) stated, more clarification and consistency is needed throughout the section 

discussing the requirements to account for non-creditable reduction calculations when 

calculating RFP emission reduction targets. The Commenter stated that, the proposal indicated 

that non-creditable emissions reductions, as specified in federal CAA (FCAA), §182(b)(1)(D), 

would no longer be calculated and removed from RFP emissions reduction targets because their 

effects are considered de minimis. The Commenter agrees that these effects are de minimis. 

However, the proposal also states that all SIP-approved or federally promulgated emissions 

reductions that occur after the baseline inventory year, except those listed in §182(b)(1)(D), are 

creditable toward RFP. These sections seem to be inconsistent, and the requirements are 

therefore unclear. The EPA should provide justification for why the non-creditable reductions 

would not be de minimis for both purposes. Is the EPA proposing that states would no longer be 

required to calculate non-creditable reductions for RFP targets but that non-creditable reductions 

must still be removed from the emission reductions used to meet RFP targets? Or is the EPA 

proposing that states would no longer be required to consider, due to their de minimis effects, 

non-creditable reductions in RFP demonstrations?

Response: The final rule provides that states would no longer be required to calculate noncreditable reductions in RFP demonstrations, due to their de minimis effects.

Comment: Do not support proposal for non-creditable reduction calculations

Commenter (0180) states that, the EPA is completely without authority to allow states to claim 

ROP credit for control measures for which such credit is explicitly barred under CAA section 

182(b)(1)(D). Commenter (0180) stated that, the prohibition on crediting such reductions is the 

sort of extraordinarily rigid statutory provision that does not allow for de minimis exceptions. 

Commenter (0180) asserted that, section 182(b)(1)(D) says unequivocally that the reductions 

from the measures listed therein “are not creditable toward the 15 percent reductions. . .” 42 

U.S.C. § 7511a(b)(1)(A). Commenter (0180) stated, the EPA has not demonstrated that the 

impact of the non-creditable reductions will always be trivial – a prerequisite to invoking the de 

minimis exception and failed to review the impact of this exception on any specific 

nonattainment areas, relying instead on national modeling from which – it concedes – local 

results may vary.

Response: The EPA disagrees. The statute provides that motor vehicle emission reductions 

resulting from measures promulgated “by January 1, 1990,” (which can only come from pre1990 vehicles), are “not creditable.” To ensure that such emissions are not credited it is first 
64

necessary to calculate them. The EPA found that making such a calculation would be “a very 

resource intensive process requiring multiple modeling runs and extensive staff time,” and that 

emissions from pre-1990 vehicles would be a very small part of the total emissions inventory by 

the time the credits could first apply, in 2017. Thus it proposed to relieve states of the burden of 

doing the calculations “based on the de minimis nature” of the potential credits. 

The comment does not dispute the principle that agencies need not apply the literal terms of a 

statute to mandate pointless expenditures in circumstances that can fairly be considered de 

minimis. See Alabama Power v. EPA, 636 F.2d 323, 360 (D.C. Cir. 1979). But the comment 

notes that this principle does not apply to “extraordinarily rigid” statutes, and baldly asserts that 

the statement in section 182(b)(1)(D)(i) that emissions are “not creditable” is such a provision. 

The comment offers no further explanation. It suggests no standard for determining when a 

statute is too rigid for de minimis exemptions, does not explain how the use of “not” makes the 

statute “extraordinarily” rigid and cites no instance when a provision like this has precluded use 

of de minimis principles in otherwise appropriate circumstances. The EPA therefore rejects the 

comment as unsupported.

The comment also claims that the EPA has not demonstrated that these circumstances are de 

minimis. Without disputing the EPA’s conclusions as to either the share of the emissions 

inventory or the resource burdens of the calculations, the comment nevertheless claims that 

because “local results may vary,” the EPA must assess “specific nonattainment areas.” The 

comment does not identify any such area or offer any basis to believe that the impact of the 

credits anywhere would be more than de minimis. Moreover, the EPA evaluated and concluded 

that reductions associated with pre-1990 vehicles “everywhere will be a very small fraction of 

the total on-road VOC emissions inventory by 2017.” In sum, this comment, too, is unsupported 

and the EPA rejects it.

4. Alternative VOC-weighted RFP approach

Comment: Support for the VOC-weighted approach

Commenters (0147, 0151, 0154, 0158, 0162, 0175 and 0179) supported the VOC-weighted 

approach. Commenters (0147, 0151 and 0179) added that controlling VOC emissions based on 

photochemical reactivity is a scientifically sound and appropriate means of addressing ozone 

formation potential. Commenter (0147) provided the following additional points. They stated 

that, scientific research shows that photochemical reactivity has a more direct correlation to the 

ozone-forming potential (i.e., potential air quality impacts) of VOC emissions than does a simple 

mass-based measure of emissions. Comparative photochemical modeling is described in (report 

attached to comment 0147), Assessing Near-field and Downwind Impacts of Reactivity-based 

Substitution. Reactivity-based VOC emissions limits, by considering the rate and mechanism of 

photo-oxidation in the troposphere, are reflective of the actual processes that lead to ozone 

formation. Relative photochemical reactivity thus provides a more rigorous scientific approach to 

assessing an individual compound’s potential contribution to ozone accumulation than 

consideration of its mass alone. The Commenters stated that, accordingly, the EPA’s approach is 

scientifically sound and represents a significant step forward in ozone regulation. The reactivity 
65

method has already been adopted in other national, state and local ozone regulations such as the 

current national aerosol coatings rule and the Texas highly-reactive VOC emissions cap and 

trade program. These programs may serve as a legal and administrative precedent for other 

reactivity-based standards. We have appended a whitepaper entitled Control of Ozone Formation 

from Household and Commercial Product Use that outlines additional information on the 

benefits and history of reactivity-based VOC regulation (report attached to comment 0147). 

Commenter (0151) supported adoption of both of the proposed alternative approaches in the SIP 

Requirements rule because they reinforce the states’ ability to apply these constructs and because 

they are far more practical and likely to be more successful in reducing ozone than the section 

182(b) RFP 15 percent VOC reductions specified in the 1990 Amendments. The Commenter 

stated that, as a consequence of this well-accepted appreciation of the relative contributions of 

different VOC species and NOx to ozone formation, it would be unreasonable and arbitrary to 

require states to impose control requirements on low-reactivity VOC where it will make little 

difference in an area’s ability to achieve the ozone standard. It would be particularly irrational to 

control such minimally reactive VOC if it is feasible to reduce higher reactivity VOC or NOx

from other sources instead. This conclusion is borne out by marked improvement in ozone 

nonattainment days following imposition of controls on highly reactive VOC in Texas. The EPA 

has proposed to codify this understanding in the proposed RFP regulations at proposed 40 CFR § 

11.1110 (a). The commenter added that Congress did not intend when it amended the CAA in 

1990 to require the states to continue to peddle a proverbial “Section 182(b) hamster wheel” 

every 5 years as the EPA reexamined and adjusted the ozone NAAQS. In that respect, we believe 

therefore that the principal function of Title I, Subpart II is to prevent any state backsliding that 

would be caused by removing features of approved RFPs and other mandate pollution controls 

required by Congress in the 1990 Amendments. At the time of the 1990 CAA Amendments, the 

Committees of the respective houses believed that many large VOC sources had not been subject 

to RACT-controls and that for most nonattainment areas that 15 percent reductions in baseline 

VOC would bring areas into attainment and that incremental additional rate-of-progress 3 

percent reductions would ultimately be successful in resolving all but perhaps the most 

intransient ozone nonattainment problems in peculiar geographically/meteorologicallychallenged areas. With this perspective, it should be concluded that subpart 2 was designed to 

forcibly dictate the floor for all nonattainment SIP programs, but that thereafter as long as states 

do not backslide from these requirements, additional measures are to be once again subject to 

state’s discretion under subpart 1 to adopt additional measures. Both alternatives that the EPA 

describes in the proposal are wholly consistent with authorities set out in CAA section 172, 

which allows the states thereafter to determine how and when the application of the alternative 

would be useful in lowering ozone in a particular air shed. The commenter argued that both of 

the proposed alternative approaches in the SIP Requirements rule are far more practical and 

likely to be more successful in reducing ozone than the section 182(b) RFP 15 percent VOC 

reductions specified in the 1990 Amendments. In combination with each other, they are likely to 

be even more successful in achieving ozone reductions in some areas. For all the reasons 

discussed on page 34190 of the NPRM, reducing NOx and highly reactive species of VOC are 

likely to result in more ozone improvement than a 15 percent overall reduction in various VOC. 

From a practical point, Dr. Douglas Carter’s reactivity tables are readily available and generally 

accepted. We believe they have been used successfully already in Texas SIP-planning to lower 
66

ozone levels closer to attainment.

Commenter (0152) generally supported the use of alternative approaches to achieving RFP and 

believed more flexibility and common sense approaches are needed in today's regulatory 

environment, as standards are getting lower and lower and available cost-effective emission 

reductions are more difficult to find. However, Commenter (0152) stated, such approaches 

should not be mandated by EPA and must be left to the state's discretion. Commenter (0154) 

stated this alternative supports a common sense approach whereby states can focus reductions on 

the particular VOC that are causing elevated ozone levels. Commenter (0162) stated, an acrossthe-board VOC reduction program in an area with significant non-reactive VOC is likely to be 

less effective than a tailored program focused primarily on highly-reactive VOC and noted that 

the ability of the Houston CMSA to significantly reduce ozone concentrations demonstrates the 

effectiveness of a VOC reactivity-based approach. 

Response: The EPA appreciates the many comments it received on this issue. Commenters 

asserted that scientific studies show that photochemical reactivity has a more direct correlation to 

the ozone-forming potential (i.e., potential air quality impacts) of VOC emissions than does a 

simple mass-based measure of emissions, and urge the EPA to allow states the option to use a 

reactivity-based approach to RFP. The EPA agrees that the alternative approach ideas discussed 

in the proposed rule and in the comments received are interesting and designed to achieve useful 

goals. However, the EPA believes that much more work is needed in a separate effort to work 

through the many scientific and legal issues involved before such an approach would be 

determined appropriate. It can be argued that the RFP requirements in section 172(c)(2) are 

defined in section 171(l) as “annual incremental reductions in emissions,” not reduction in 

ambient pollutant levels. Also, section 182(b)(1) requires plans for Moderate and above areas 

that provide for specific overall percentage reductions in emissions, and those reductions must be 

achieved “from baseline emissions” regardless of the reactivity of the VOC being reduced. The 

EPA recognizes that even though the science of reactivity has advanced to a point where it could 

support policy directives, this alternative approach would be complicated to implement. 

The EPA did not specifically include this alternative approach in the final rule, however the EPA 

believes there is potential for this alternative to be implemented in the future. If a state or another 

air quality management entity were to develop a weighted VOC approach that is adequately 

supported by scientific studies and consistent with the CAA requirements, the EPA could 

evaluate the program and the studies to determine if it could be readily implemented in a separate 

rulemaking. The EPA believes that states and the agency will need time to understand and 

consider the outcomes and whether it may be practical for the states to pursue this alternative, 

possibly on a case-by-case basis. If the EPA determines in the future that such an approach 

appropriately meets CAA obligations, it will be established in a separate rulemaking action.

Comment: EPA should suggest in the final rule what those “reactivity groupings or ‘bins’” 

would be or incorporate the reactivity scales adopted by California agencies

Commenters (0151, 0158, 0166 and 0175) suggested the EPA should establish default national 

VOC weighting ratios. Commenter (0151) stated that, requiring states to make demonstrations 

based on the relative reactivity of pollutants would be burdensome and unnecessary duplicative 
67

since any such demonstration would likely depend on the same detailed analysis of the 

atmospheric chemistry and behavior of families of VOC. Commenter (0151) requested the EPA 

to suggest in the final rule what “reactivity groupings or ‘bins’” would be or incorporate the 

reactivity scales adopted by California agencies. The commenter stated that, this is not to imply 

that all nonattainment areas are the same, in the sense of their make-up of sources or the 

predictability of emission reductions from certain sources. That analysis will need to be guided 

by other local criteria that the states will need to use for implementing the RFP, such as the 

NOx/VOC ratio and other variables involving monitors and terrain and weather. But at least 

having the EPA classify three (or more as the science supports) tiers of VOC based on their 

relative reactivity and assign ratios for comparison is simpler than burdening state governments 

with overcoming the challenge of documenting why they chose to define the “reactivity bins” 

themselves, allowing them to focus limited resources on unique issues related to their industrial 

and area source emission inventories.

Commenters (0158 and 0166) supported the proposed option and stated that, if the agency does 

provide this alternative RFP option in the final rule, it should allow states the option to use the 

EPA-developed and provided default VOC weighting functions or to develop alternative state- or 

area-specific weighting functions. Commenter (0175) stated, the EPA should establish default 

national VOC weighting ratios through rulemaking and allow states the flexibility to establish 

region specific VOC weighting ratios with review and approval from the EPA. 

Response: The EPA appreciates the commenters’ suggestions on ways to make the VOC 

weighting approach a viable approach. However, the EPA also recognizes that there are lingering 

legal issues, scientific unknowns and uncertainties associated with developing and implementing 

defensible methods that allow the weighing of VOC emissions based on ozone reactivity for 

purposes of meeting RFP requirements. The EPA recognizes such an approach would provide 

states with increased flexibility. While interested in exploring ways to provide flexibility to states 

where possible, the EPA has decided not to include this alternative approach in the final rule at 

this time. The EPA believes there is potential for this alternative to be implemented in the future.

Comment: Concerns regarding the VOC-weighted approach

Commenters (0132, 0144, 0146, 01060 and 0166) expressed concerns related to the alternative 

VOC-weighted RFP approach. Commenter (0132) stated, the proposal does not provide enough 

detailed information on how a VOC-weighted approach would be practically implemented and 

requested the EPA provide additional guidance and/ or clarification as to how the alternative 

approaches would be implemented. Commenter (0144 and 0146) stated that, there is not enough 

scientific data and guidance available to implement this approach, especially considering that 

even low reactivity VOC do have adverse ozone impacts downwind. Commenter (0160) stated, 

the proposed alternative to allow weighting of VOC emissions according to reactivity would be 

of limited utility in California, unless it is expanded to weight the value of NOx reductions 

relative to VOC reductions. Commenter (0166) stated that, to the extent legally permissible, the

EPA should clarify that it is looking for the best mix of both VOC and NOx emission reductions 

when it states that “[t]he emission reduction targets for the area should be expressed in terms of 

the pollutant (VOC or NOx) which, when reduced, is most effective in reducing ozone 

concentrations in the area.” 78 FR at 34,190/1. 
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Response: The EPA agrees that there are concerns in implementing a VOC weighted approach. 

The EPA also recognizes from concerns expressed by Commenters that, there may be lingering 

legal issues and that the underlying science has some uncertainties associated with the reactivity 

of VOC approach. The EPA recognizes the alternative VOC-weighted approach would provide 

states increased flexibility in satisfying ROP/RFP requirements. However, the EPA has decided 

not to include this alternative approach in the final rule at this time. The EPA believes there is 

potential for this alternative to be implemented in the future and if the EPA decides to make this 

approach available, it will do so in a separate rulemaking.

Comment: Do not support the VOC-weighted approach

Commenters (0146, 0163 and 0168) opposed this approach, stating that the CAA clearly requires 

a percentage reduction “from baseline emissions” for purposes of RFP. Commenter (0163) added 

that, the CAA specifies a percentage reduction and even provides for alternatives for using a 

percentage less than 15 percent for RFP (CAA section 182(b)(1)(A)(ii). While reactivity-based 

weighting is recognized in another section of subpart 2, it is not mentioned in this context. 

Furthermore, this approach would presumably only be utilized by states to avoid either meeting 

the 15 percent VOC reduction requirement or to permit the substitution of NOx prior to meeting 

the 15 percent VOC requirement. Neither is allowed under the CAA.

Response: The EPA believes that it might be argued that there are legal barriers to implementing 

the VOC reactivity-based alternative approach. The Commenter argues that, section 

182(b)(1)(A)(ii) provides a specific reduction percentage with an alternative for using a 

percentage less than 15 percent for ROP/RFP and prohibits the weighted VOC approach. 

However, the EPA disagrees with the Commenter that states would use this approach only as a 

means to avoid meeting the 15 percent VOC reduction requirement. The EPA believes there is 

potential in this approach and if the EPA decides to propose a change, it will be undertaken in a 

separate rulemaking action.

5. Alternative Air quality approach

Comment: Concerns regarding the alternative air quality approach

Commenters (0132, 0144, 0159 and 0166) expressed concerns related to the alternative air 

quality based RFP approach. Commenters (0132 and 0166) stated, the proposal does not provide 

enough detailed information on how an air quality-based approach would be practically 

implemented. Commenter (0132) added that, for the air quality-based approach, without more 

detail on how the EPA would expect states to translate RFP emissions reduction targets (tons) 

into ozone air quality targets (ppb), it is difficult to provide comment. Based on the brief 

summary provided by the EPA, the Commenter assumes, that additional photochemical 

modeling would be required to achieve this translation. The EPA should provide additional 

guidance and/ or clarification as to how both these alternative approaches would be 

implemented. Commenter (0166) added that, the air quality alternative proposal appears to be 

reasonable on its face, but it is not clear how it would work and the EPA should provide further 

detail on this alternative in a supplemental notice (with an opportunity for public comment) if it 

decides to adopt this approach in the final rule. It is not clear from the proposed rule to what 
69

extent an ambient measurement approach is consistent with the statutory definition of “RFP,” 

which requires “annual incremental reductions in emissions of the relevant air pollutant.” CAA § 

171(1). The EPA needs to provide in a supplemental notice additional legal justification for such 

a proposal if it decides to proceed to adopt it. To the extent legally permissible, the EPA should 

clarify that it is looking for the best mix of both VOC and NOx emission reductions when it states

that “[t]he emission reduction targets for the area should be expressed in terms of the pollutant 

(VOC or NOx) which, when reduced, is most effective in reducing ozone concentrations in the 

area.” 78 FR at 34,190/1. 

Commenter (0144) stated, there is not enough scientific data and guidance available to 

implement this approach and, even low reactivity VOC do have adverse ozone impacts 

downwind. The commenter stated that, it is not clear how a state would distinguish between 

reductions from control measures, transport and natural or nonpermanent reductions. This 

approach is more complicated and not as accurate as the current requirement in assessing control 

measure benefits from individual control measures.

Response: It can be argued that the RFP requirements in section 172(c)(2) are defined in section 

171(l) as “annual incremental reductions in emissions,” not reductions in ambient pollutant 

levels. Also, section 182(b)(1) requires plans for Moderate and above areas provide for specific 

overall percentage reductions in emissions and those reductions must be achieved “from baseline 

emissions” regardless of the air quality targets of the criteria pollutant being reduced. The EPA 

recognizes that an alternative approach would be complicated to implement because the science 

of the air quality targeting approach has to advance to a point where it could support policy 

directives. The Commenters plainly contend that the CAA's RFP provisions do not appear to 

provide for variations in the required percent reduction in VOC based on differences of ozone 

forming potential. The requirement to obtain the required percent reduction of total VOC 

remains, and if EPA decides to propose a change, it would be undertaken in a separate 

rulemaking action.

Comment: Support for increased flexibility in air quality approach

Commenters (0132, 0136, 0139, 0140, 0150, 0151, 0153, 0160, 0161, 0175 and 0179) generally 

supported the air quality approach. Commenters (0132 and 0161) stated this, approach provides 

increased flexibility since it would provide an avenue by which VOC and NOx emissions could 

be substituted for one another on an air-quality basis instead of on a percent-for- percent 

emissions basis. Commenter (0132) endorsed this increased flexibility since it would provide an 

avenue by which VOC and NOx emissions could be substituted for one another on an air-quality 

basis instead of on a percent-for-percent emissions basis. Commenters (0136 and 0139) stated, 

this approach would allow us to translate the region's RFP emissions reduction targets (tons) into 

ozone improvement targets (ppb) based on air quality modeling or other appropriate analyses. 

Commenter (0136) stated, the emission reduction targets for the area should be expressed in 

terms of the pollutant (VOC or NOx) which, when reduced, is most effective in reducing ozone 

concentrations in the area. Commenters (0150 and 0160) supported the proposal to allow use of 

an air quality based approach to demonstrating RFP, especially if the proposal to disallow use of 

emission reductions from outside a nonattainment area is finalized. 
70

Commenter (0160) stated, that this alternative would better reflect the air quality progress being 

made in areas adjacent to the South Coast nonattainment area, such as Coachella Valley and the 

Western Mojave Desert, which must rely on large upwind emission reductions to attain the 

ozone standard. In addition, there may be other appropriate uses of air quality based progress 

benchmarks to demonstrate RFP. States should have the opportunity to demonstrate that such an 

approach is equivalent to or better than an emission reduction target. Such an alternative would 

qualify as an equivalent planning procedure that can be approved under section 172(c)(8) and 

should be included in the final rule. 

Commenter (0150) stated that, this approach would be very useful because their best technical 

judgment is that the Coachella Valley will be able to meet the air quality improvement targets, 

but would not necessarily be able to meet the RFP tonnage targets using emission reductions 

solely from within the Coachella Valley nonattainment area. The Commenter added that, the 

EPA has requested comment on whether there is adequate legal basis to allow such an 

interpretation. Again, the basic purpose of RFP is to ensure adequate and consistent annual 

emission reductions to ensure progress toward attaining the standards. CAA § 171(1). The 

requirement to reduce tons of emissions is, of course, intended to produce improvements in air 

quality. The EPA’s proposed air quality-based approach clearly qualifies as an equivalent 

planning procedure that is not “less effective” than the bare requirement to reduce tons. Thus, the 

EPA may approve it under CAA § 172(c)(8). It may be argued that under this section, the EPA 

may only approve equivalent methods to those "specified by the Administrator," not those 

specified in the CAA. But that argument assumes that each and every word of Subpart 2 is 

directly applicable to the revised standard. As explained above, it is not. The EPA may 

reasonably assume that Congress would have wanted states to be allowed to use measures of 

progress that are directly related to the goal, i.e., air quality improvement. 

Commenter (0179) stated that, the approach is feasible given the current state of science and 

modeling tools available to measure RFP in terms of ozone improvement targets. It can serve as 

a menu of choices that states and the EPA can use to measure progress toward and to attain the 

ozone standard. It would retain a state’s accountability for making consistent incremental 

progress while focusing on the most direct measurement of improvement, namely air quality. We 

recognize that a similar approach is already included in the implementation rules that govern SIP 

development for the June 6, 2012 court decision on PM2.5 NAAQS (40 CFR 51.1009(g) and (h)), 

and the same logic could be applied for 2008 ozone NAAQS implementation. The Commenter 

believes that sections 1 (b)(4) and 6(a) of the Executive Order 13563 could be applied to serve 

the overall intent of the CAA to attain the NAAQS in an expeditious manner. In particular 

section 1 (b)(4) states, “to the extent feasible, specify performance objectives, rather than 

specifying the behavior or manner of compliance that regulated entities must adopt” and section 

6 (a) states, “To facilitate the periodic review of existing significant regulations, agencies shall 

consider how best to promote retrospective analysis of rules that may be outmoded, ineffective, 

insufficient or excessively burdensome, and to modify, streamline, expand, or repeal them in 

accordance with what has been learned. Such retrospective analyses, including supporting data, 

should be released online whenever possible.” 

Commenter (0151) supported adoption of both of the proposed alternative approaches in the SIP 
71

Requirements rule because they reinforce the states’ ability to apply these constructs and because 

they are far more practical and likely to be more successful in reducing ozone than the section 

182(b) RFP 15 percent VOC reductions specified in the 1990 Amendments. With respect to 2008 

ozone nonattainment areas where portions have a previously approved 15 percent VOC reduction 

plan, Commenter (0179) requested maximum flexibility in dealing with nonattainment areas. 

Commenter (0179) stated that, air quality improvements are better accomplished with current 

scientific understanding rather than mandates in a law from a generation ago that was aimed at 

achieving compliance with a different air quality standard prior to emission reduction 

achievements from many sources of VOC and NOx. 

Commenters (0155 and 0157) stated, they had no comment on these specific proposals regarding 

alternative approaches to achieving RFP or their legal merits, but noted that some state and local 

agencies will face serious difficulties achieving the required RFP reductions by the prescribed 

deadlines. Commenters (0155 and 0157) urged, the EPA to engage in meaningful and timely 

dialogue with states and localities on this issue and to provide states and localities all legally 

available flexibility in reaching attainment, provided there is no adverse effect on other states’ 

efforts. 

Response: The EPA appreciates the commenters’ support. We recognize that implementing 

alternative approaches such as the weighing of VOC emissions based on ozone reactivity may 

provide states increased flexibility in satisfying RFP requirements based on air quality 

improvements rather than adopting control methods to meet prescriptive emission limits. Air 

quality improvements recognize the benefits or reducing both VOC and NOx where one could be 

substituted for another.

The EPA also recognizes that there are lingering legal and technical issues, unknowns and 

uncertainties associated with allowing either the air quality improvement approach or the 

weighting of VOC emissions based on ozone reactivity. It can be argued that the RFP 

requirement in section 172(c)(2) is defined in section 171(l) as “annual incremental reductions in 

emissions,” not reduction in ambient pollutant levels. Also, in the section 182(b)(1) requires 

plans for Moderate and above areas to provide for specific percentage reductions in emissions, 

and those reductions must be achieved “from baseline emissions” regardless of how much ozone 

levels are reduced. The EPA recognizes that this alternative would be complicated to implement 

because it would require the state to determine the percentage emissions reduction and translate 

that result into an air quality benefit and subsequently determine if control programs would result 

or have resulted in an equivalent air quality benefit. However, Congress has expressly allowed 

air quality benefits analyses to supplant emission control requirements in certain sections of the 

CAA. For example, section 182(f) provides for waiver of certain NOx control requirements for 

major sources where the EPA determines that net air quality benefits are greater in the absence of 

NOx reductions from the sources concerned.

The EPA has not included these alternative approaches in the final rule, however, the EPA 

believes there is potential for these alternatives to be implemented in the future. If EPA decides 

to propose a change, it would be undertaken in a separate rulemaking action.
72

Comment: Do not support air quality approach

Some Commenters (0146, 0154, 0163, 0168 and 0180) did not support the air quality approach. 

Commenter (0146) opposed this approach, stating that, the CAA clearly requires a percentage 

reduction “from baseline emissions” for purposes of RFP. Commenter (0154) stated, it is not a 

requirement of the CAA, places a severe additional burden on the states to complete a difficult 

and costly technical demonstration and was not developed in the spirit of Executive Order 13563 

to improve regulation. Commenter (0163) stated that, because of the legal issues and other 

complications, unknowns, uncertainties and questions, the EPA should not offer this alternative 

and instead implement the CAA as written. The commenter added that, the alternative to convert 

to an equivalent ozone improvement metric does not appear to be consistent with the CAA, 

which requires a percentage reduction "from baseline emissions." In addition, this alternative 

would be more complicated to implement than the requirement as specified in the CAA as it 

would entail determining the percentage reduction, translating that into an air quality benefit and 

then determining if the control programs developed would in fact result in an equivalent air

quality benefit. If an area is NOx limited, a reduction in VOC would result in a de minimis ozone 

benefit which in tum would be equivalent to a de minimis NOx reduction. This would effectively 

result in no NOx reductions being determined equivalent for RFP purposes. New York, therefore, 

believes there is no sound policy or legal basis for this approach. In addition, this approach fails 

to consider the impact of emissions from outside a given state on its ability to reduce ozone 

levels. Furthermore, slower reacting VOC could lower ozone in the immediate area and create 

more ozone downwind and ground level emissions have different impacts that elevated sources. 

(0163)

Commenter (0168) did not support translating an area’s RFP emissions reduction targets (tons) 

into ozone improvement targets (ppb) based on air quality modeling or other appropriate 

analyses. Commenter believes, that RFP must be calculated and complied with as a percentage of 

base year inventory emissions, which is consistent with the plain reading of the CAA and with 

prior EPA interpretations and has resulted in the necessary control of both VOC and NOx

emissions in the covered areas.

Commenter (0180) stated that, the alternative is not legally permissible, to the extent the EPA is 

proposing to allow a nonattainment area to avoid providing for, or actually achieving, the 

statutorily required percentage emission reductions as long as it achieves specified reductions in 

ozone levels. Commenter (0180) asserted that, section 182(b)(1) requires plans for Moderate and 

above areas to provide for specific percentage reductions in emissions, and those reductions must 

be achieved regardless of how much ozone levels are reduced. Likewise, Commenter (0180) 

stated the “RFP” required under section 172(c)(2) is defined in section 171(1) as “annual 

incremental reductions in emissions” – not reductions in ambient pollutant levels. 42 U.S.C. §§ 

7501(1) and 7502(c)(2). In addition, Commenter (0180) stated, section 182(g) requires that 

compliance with subsections 182(b)(1), (c)(2)(B) and (C), (d) and (e) be determined based on 

whether the area “has achieved a reduction in emissions” equivalent to “the total emission 

reductions required to be achieved” by those subsections. Id. § 7511a(g)(1). Commenter (0180) 

concluded that, the language of the Act forecloses substitution of air quality improvements for 
73

the required percentage reductions in emissions, either in establishing SIP requirements or in 

determining compliance with ROP requirements. 

Commenter (0180) added that, where Congress has intended to allow an air quality benefits 

analysis to supplant emission control requirements, it has expressly said so. Commenter (0180) 

stated, the EPA’s proposed air quality benefits approach would also be arbitrary and capricious 

as there would be no requirement that the state establish that the reduction in ambient ozone 

levels is not due to a random factor such as the weather, the economy or temporary voluntary 

actions by certain polluters. For example, Commenter (0180) stated, that the 2008 to 2010 period 

saw much lower ambient ozone levels due to weather and the recession, whereas, in 2012, 

ambient ozone levels went back up, but the EPA had taken regulatory actions based on the lower 

2008 to 2010 data so that many mechanisms to address the 2012 levels in a timely manner are 

not in place. 

Regarding, the weighting of the amount of ROP credit given for reductions of individual species 

(or similar groups) of VOC based on their ozone forming potential, Commenter (0180) asserted 

that section 182(b)(1) requires that plans for Moderate and above areas provide for VOC 

“emission reductions. . . of at least 15 percent from baseline emissions,” and defines “baseline 

emissions” as “the total amount of actual VOC or NOx emissions from all anthropogenic sources 

in the area. . .” 42 U.S.C. § 7511a(b)(1) (emphasis added). Thus, Commenter (0180) asserted the 

statute requires a 15 percent cut in the total amount of actual VOC emissions, not some lesser 

percentage reduction based on claims that some VOC have greater ozone-forming potential than 

others.

Response: The EPA appreciates the Commenters’ concerns. The EPA believes that while the 

alternatives are a reasonable concept, the detailed information necessary to direct states on how 

to implement either an air quality-based approach or a VOC-weighted approach is inadequate 

and more research and investigation must be completed. The EPA has not included these 

alternative approaches in the final rule, however, the EPA believes there is potential for these 

alternatives to be implemented in the future and the EPA will consider the flexibility of suitable 

methods to allow states to address RFP requirements. If EPA decides to propose a change, it 

would be undertaken in a separate rulemaking action.

6. Baseline year for RFP

Comment: Support most recently available triennial inventory

Commenters (0143, 0159, 0163 and 0179) generally supported the use of the most recently 

available triennial emission inventory at the time RFP plans are developed. Commenter (0143) 

supported using the latest triennial inventory, provided the state’s version of the inventory is 

used for SIP submittal purposes when discrepancies exist between versions of the state’s and the 

EPA's inventory. The Commenter added that using the most up-to-date triennial inventory as a 

base year inventory should reduce inventory development burden for states. Nevertheless, the 

EPA in some cases refines or "augments" the triennial inventory that the DEP submits to the 

EPA in ways that DEP does not support. For instance, DEP does not agree with an EPA 

augmented version of emission estimates of Pennsylvania Marcellus Shale gas activity submitted 
74

by DEP. DEP strongly believes if DEP and the EPA cannot agree on some aspect of the triennial 

inventory, DEP should be able to use the version of the inventory that DEP deems the most 

accurate. For purposes of a SIP submittal, a reasonable version of DEP's inventory, produced 

with due diligence should be approved by EPA.

Response: For the 2008 ozone NAAQS, the EPA is specifying as the baseline year for RFP, the 

calendar year for the most recently available triennial emission inventory at the time of 

designation, which for areas designated nonattainment effective July 20, 2012 translates to 2011. 

Additionally, the EPA is also providing states with the option of selecting an appropriate and 

justifiable alternate year between the years of 2008 to 2012 as a baseline year for RFP. We 

finalized a nearly identical interpretation for purposes of implementing the 1997 ozone NAAQS. 

See 40 CFR 51.910(d). For the 1997 ozone NAAQS, our regulations also provided that a state 

has flexibility to use an alternative baseline year if it shows that the alternate year is appropriate 

and justifiable. We believe it is appropriate to continue to apply these policies to the 2008 ozone 

NAAQS. 

Comment: Support use of 2011 baseline year

Some Commenters (0130, 0143, 0154 and 0175) generally supported use of 2011 as the base 

year. Commenter (0130) stated that, use of the 2011 base year rather than 2007 is supportable for 

many reasons, however, the EPA should acknowledge in its preamble that timing and resource 

factors exist and that, unless additional resources are provided, documentation for the 2011 base 

year as well as for future year inventories and modeling results will be minimal at best in SIP 

submittals as resources are not available for developing in depth documentation. The Commenter 

added that the CAMD data for 2011 partially reflects the EGU sector's growing reliance on 

natural gas as a fuel source, as do 2011 activity data for the area and non-EGU point sectors. Onroad data for 2011 also reflect alterations in driving patterns due to the increases seen in the cost 

of fuel. However, the EPA should realize that the development of a 2011 base year inventory is a

significant and costly undertaking for states and MPOs. Very little money exists for such efforts, 

and timing is a significant issue. The preamble noted the following: “. . . As noted above, the 

AERR Rule required states to report emissions for calendar year 2011 to the EPA by December 

31, 2012. This is about 2.5 years before the attainment date deadline for 15 percent RFP plans to 

be submitted. . .” The commenter argued that just because AERR inventories are submitted to the 

EPA in that timeframe does not mean that regional inventories are then immediately available for 

review by state staff nor have the data been processed via SMOKE for attainment modeling 

demonstrations. Additionally, time must be provided for the creation of base year documentation 

as well as for the development and documentation of future year inventories. To develop base 

year inventories, the MOVES and NONROAD models must be run using area-specific inputs. 

EGU data must be developed and quality assured. Data gaps within the NEI must be back filled 

using defensible data sources. These are time consuming and resource consuming efforts. In the 

attainment modeling, the use of a 2011 base year requires the design value data for 2013 be 

available, since the recommended approach to modeling design values is to use a 5-year span. In 

the case of 2011, this 5-year span would be 2009 through 2013. A switch to 2011 as the base 

year would also necessitate the development of new meteorological data and base case model 

performance analyses. Commenter (0175) supported using 2011 as an emissions base year 

because it is a National Emissions Inventory (NEI) year and it was a fairly representative ozone 
75

season not biased by climatologically abnormal meteorological conditions.

Response: The EPA acknowledges the resource and timing challenges posed by the 

implementation requirements and timing of the final rule. The EPA is making earnest efforts to 

assist states in meeting the requirements of the rule. The EPA has created and released a 

complete modeling platform using 2011 emissions data and other modeling components, and has 

made this available to states for use and review in preparing their SIPs. While additional updates 

may be needed in some areas, the EPA believes that the data provided to date should allow states 

to meet their plan development obligations in an expeditious manner.

Regarding the use of local-specific mobile model inputs, the EPA has made every effort to 

include such inputs in its 2011 modeling platform. Where states elect to further refine the EPA 

approach for their areas, that may include modeled attainment demonstrations, but perhaps at the 

cost of time and resources as the commenters point out.

The EPA appreciates the commenters’ support for establishing the baseline year of 2011 for RFP 

SIPs. For the 2008 ozone NAAQS, we are finalizing as proposed a baseline year of 2011. While 

2011 may be the most suitable year for many areas, we believe it is appropriate to provide some 

flexibility to choose an alternate year that falls between the year the NAAQS was established 

(2008) and the year of designation (2012 for the initial area designations). The final rule will 

provide states with the option of selecting an appropriate and justifiable alternate year between 

the years of 2008 to 2012 as a baseline year for RFP for areas designated nonattainment in July 

2012. We finalized a nearly identical interpretation for purposes of implementing the 1997 ozone 

NAAQS. See 40 CFR 51.910(d). For the 1997 ozone NAAQS, our regulations also provided that 

a state has flexibility to use an alternative baseline year if it shows that the alternate year is 

appropriate and justifiable. We believe it is appropriate to continue to apply these policies to the 

2008 ozone NAAQS. 

Comment: Flexibility on RFP base year

Commenters (0139, 0141, 0144, 0153, 0155, 0157, 0160 and, 0177) generally agreed with the 

EPA’s proposed flexibility on the base year for RFP reductions. Commenter (0144) supported 

the flexibility in the rule for a state to use an alternative baseline year for RFP, including 2007. 

The commenter stated that, the year 2007 was chosen as the regional baseline year for modeling 

in the Northeast/Mid-Atlantic States. Development of this SIP quality inventory was a significant 

investment by the Northeast/Mid-Atlantic States. In addition, states that took early action on 

control measures, such as updating 1990 RACT controls, should not be penalized. The same 

rationale that the EPA applied in the selection of the 2002 base year could be applied in this 

situation. (70 FR 71638, November 29, 2005) EPA stated in the 11/29/2005 rule, that while there 

would be a difference in the RFP requirement based on the choice of the RFP baseline, there 

should be little if any difference in terms of emissions reductions needed to demonstrate timely 

attainment. If a state uses an earlier base year, the state can take credit for additional emission 

reductions, and the state also has a higher baseline to start from and additional target years before 

attainment. The commenter urged the EPA to allow for emission reduction credits from certain 

control strategies made within the Ozone Transport Region (OTR) states that occurred between 
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2008 and the year of the baseline emissions inventory (2011), if 2011 is used as the baseline 

inventory, so that states that made early reductions in ozone precursors are not economically and 

environmentally disadvantaged.

Commenter (0140) urged, the EPA to allow states to use 1990 or another year relevant to the 

adoption of emission reduction measures as the baseline (for the Austin-Round Rock area, it 

would be 2002 or 2005 in conjunction with the EAC SIP). Commenter (0140) stated, the EPA 

should allow states to model the baseline emissions used for setting RFP targets without 

including emission reduction measures that were adopted prior to the baseline year (such as the 

voluntarily adopted inspection and maintenance program in place in Travis and Williamson 

Counties) so as not to penalize areas for taking proactive measures prior to being designated 

nonattainment. 

Commenters (0153, 0155 and 0157) supported the EPA's proposal to allow states the flexibility 

of selecting a year prior to 2011 as the RFP baseline year with the understanding that this would 

require an additional 3 percent emission reduction for each year prior to 2011. Commenter 

(0160) supported the flexibility and noted that, the SCAQMD staff proposes to use 2012 as its 

baseline year because it corresponds to baseline year for the 2016 regional transportation plan to 

be prepared for the region. [Also see discussion later in this section.] Commenter (0177) agreed 

that, this is a reasonable approach, as long as sufficient justification is provided and the alternate 

baseline year does not significantly deviate from the design value period used to establish 

designations.

Commenters (0149 and 0150) urged EPA to allow for a baseline year later than 2011 for RFP 

calculation, if appropriate and justifiable. Commenters (0149 and 0150) added that, the draft rule 

discussed provisions for use of a baseline year of 2011 or earlier for the emission inventory for

meeting the RFP requirement. However, the SCAQMD proposes to use the year 2012 as its 

baseline year because it corresponds to the baseline year for the 2016 regional transportation plan 

to be prepared by the Southern California Association of Governments (SCAG) for the sevencounty southern California region of which the SCAQMD is a part. Under state law, the 

SCAQMD is required to use SCAG's demographic projections and transportation strategies in its 

air quality plan. Cal. Health & Safety Code § 40460(b). Matching two different baseline years 

creates a great deal of extra work and some uncertainty in the baseline inventory that can be 

avoided by using the same year for both plans. SCAQMD staff would like to confirm our 

understanding from EPA staff that the same timeframes for RFP still apply in this case; i.e., an 

area with a baseline year of 2012 would have until the attainment date at the end of 2018 to 

demonstrate 15 percent reductions. 

Response: For the 2008 ozone NAAQS, the EPA is providing that states should use as the 

baseline year for RFP, the calendar year for the most recently available triennial emission 

inventory at the time ROP/RFP plans are developed, which in the case of areas designated 

nonattainment in 2012 translates to 2011. We are finalizing, as proposed, that all SIP-approved 

or federally promulgated emission reductions that occur after the baseline emissions inventory 

year from sources located in the nonattainment area are creditable for purposes of the ROP/RFP 

requirements, provided the reductions meet the standard requirements for creditability and are 
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not prohibited by section 182(B)(1)(D) of the CAA. We finalized a similar interpretation for 

purposes of implementing the 1997 ozone NAAQS (40 CFR 51.910(d)) to the nearest calendar 

year, however, we are allowing states to select baseline years from a limited range of alternate 

years in the final rule for the 2008 ozone NAAQS. We received support from Commenters that 

2011 would be an appropriate baseline year while other Commenters urged the EPA to allow the 

option of justifying an alternative baseline year, including 2012, 2008, 2007 and 1990. In 

determining the appropriate alternate years, the EPA recognizes that some states may have 

initiated certain control strategies between the year the standard was finalized (2008) and the 

most recently available triennial emission inventory year (2011), and that, it would be 

appropriate to recognize these recent investments in implementing early reductions to achieve 

improved air quality. We also believe that allowing alternate baseline years prior to 2008 (e.g., 

1990 and 2007) would not be appropriate because we believe that it is necessary for RFP credit 

for attainment planning to be tied as directly as possible to promulgation of the 2008 ozone 

NAAQS. Emission reductions occurring prior to promulgation of the 2008 NAAQS from 

measures adopted into the SIP prior to promulgation of the 2008 NAAQS are certainly helpful 

for improving air quality and consequently, may lower the nonattainment classification of an 

area and the base year emissions level. However, they are not unquestionably tied to attainment 

planning for a standard that was not established final until 2008, and the associated 

nonattainment designation for that standard which did not exist until 2012. Therefore, we have 

determined these emissions reductions are not appropriate to be credited for fulfilling 

nonattainment area RFP requirements. We also recognize that since we designated most areas on 

April 30, 2012, with an effective date 60 days after publication in the Federal Register (FR), that 

2012 (the designation year) is an appropriate alternative baseline year consistent with the subpart 

2 structure. With these considerations, the EPA is finalizing that states may use an alternate year 

(i.e., other than 2011) between the years of 2008 to 2012 that the state justifies as appropriate.

Lastly, the EPA confirms the commenter’s understanding that the RFP timeframes for an area 

with a baseline year of 2012 would have until July 20, 2018 to demonstrate 15 percent 

reductions. 

Comment: Additional 3 percent emissions reduction per year

Commenters (0153, 0155 and 0157) supported the EPA's proposal to allow states the flexibility 

of selecting a year prior to 2011 as the RFP baseline year with the understanding that this would 

require an additional 3 percent emission reduction for each year prior to 2011.

Commenters (0154, 0158 and 0166) stated the EPA should not penalize states for choosing early 

baseline years in establishing and demonstrations RFP requirements. Commenters (0154 and

0158) recommended that the EPA allow for selection of an earlier baseline year, but drop the 3 

percent per year penalty. Commenter (0154) questioned why the EPA imposes an additional 3 

percent per year penalty for every year prior to 2011 selected for a base year—the penalty for 

early reductions tells states that early reductions are a bad idea, that the state is better off waiting 

until the EPA publishes an implementation plan. Commenter (0158) stated, it is not clear why 

the EPA would penalize states for choosing an earlier baseline year, nor is it clear that such a 

penalty is justified by the statute which simply requires a 15 percent VOC reduction below the 

baseline year. Commenter (0166) stated, the EPA cannot properly penalize states (i.e., require 
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more emission reduction than the required 6 percent) for choosing an earlier baseline year for 

Moderate areas, because no such penalty is justified under the statute, which simply requires a 15 

percent VOC reduction below the baseline year. The Commenter added that, under the proposed 

rule, the choice of a 2011 baseline year would likely mean that the same baseline year generally 

would be used for both RFP purposes and attainment demonstration modeling purposes because 

the EPA guidance on attainment demonstration modeling recommends the use of the average of 

the three three-year design value periods that include the baseline inventory year (e.g., for a 2011 

baseline inventory year, the three three-year periods would be 2009-11, 2010-12 and 2011-13). 

See EPA, EPA-454/B-07-002, “Guidance on the Use of Models and Other Analyses for 

Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5 and Regional Haze,” April 

2007, at 22, available at http://www.epa.gov/ttn/scram/guidance_sip.htm. The EPA should make 

clear that a state may choose a different baseline period for attainment demonstration modeling if 

the state concludes that that period is more meteorologically representative than the period that 

would result from use of the RFP baseline year.

Commenter (0132) stated that, the EPA should more clearly define the "whatever additional 

emissions reductions" requirement for January 1, 2018 to December 31, 2018 as a specific 

percentage (such as 3 percent). The Commenter argued that, because RFP calculations are based 

on emissions reductions (tons) and not ozone concentrations (ppb); it is difficult to define these 

"whatever additional emissions reductions." For areas that choose a pre-2011 baseline year, the 

EPA has proposed that the area is responsible for a specific 3 percent emissions reduction each 

year after the initial 6-year period has concluded up to the beginning of the attainment year. The 

EPA should apply the same requirement to Moderate areas that choose 2011 as a baseline year 

(as recommended by the EPA's proposal) and require an additional 3 percent emissions reduction 

for the final year before the attainment deadline. This approach would be more clear and 

consistent between areas that choose 2011 as a baseline year and those that choose a different 

year. It would also be more consistent with the EPA's proposal for Serious and higher 

nonattainment areas to provide an additional average of 3 percent emissions reductions beyond 

the initial 6-year period through the attainment year. If the EPA chooses to leave the "whatever 

additional reductions needed" requirement in the final rulemaking rather than change it to a 

specific percentage requirement, then the Commenter (0132) suggests that, the EPA also include 

a method for calculating the requirement.

Response: The EPA believes it is reasonable to provide flexibility to states in selecting an 

appropriate alternate baseline year within the authorities provided to the EPA by the CAA. In the 

final rule, the EPA has selected a baseline year of 2011, but is also allowing states to select an 

alternate baseline year that would occur no earlier than 2008 and no later than 2012. The EPA 

believes this conforms with the language of both the CAA and the NEI cycle. As noted above, 

the use of an alternative year for the baseline inventory for RFP does not change the requirement 

to use 2002 as the baseline year for transportation conformity as described in 40 CFR 93.119.

The EPA disagrees with the Commenters’ assertion that, the EPA is penalizing states for 

selecting pre-2011 years as their baseline. The CAA contains three separate provisions regarding 

RFP. Section 172(c)(2) under subpart 1 contains a general requirement that nonattainment plans 

require RFP, while sections 182(b)(1) and (c)(2) under subpart 2 contain specific percent 
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reduction targets for Moderate and above and Serious and above areas, respectively. A state 

ROP-RFP plan must show increments of progress from the baseline emissions inventory year out 

to the attainment date. We do not believe it is a penalty as described by the commenters. 

However, we are certain that our policy is consistent with the CAA subpart 2 and 172 

requirements because by allowing 2008-2010 reductions to be credited, we continue to provide 

an incentive for early reductions prior to designations. 

The RFP plan for a Moderate area must show increments of progress from the baseline emissions 

inventory year (2011/2012) out to the attainment date (no later than July 20, 2018). The RFP 

plan would first have to provide for a 15 percent emission reduction from the 2011/2012 baseline 

year within 6 years after the baseline year. We have consistently indicated that Moderate areas 

must “achieve” the reductions need to provide for attainment by July 20, 2018. Therefore, if 

2011 is used as the base year for an RFP plan, a 15 percent reduction must be shown between 

January 1, 2012 and December 31, 2017, and “whatever additional reductions needed” must 

occur by the end of 2018 in order for the area to attain. The final rule specifies that RFP for this 

1-year gap period is whatever additional emissions reductions are needed to achieve the goal of 

attainment. We believe that requiring Moderate areas using 2011 as a base year to obtain an 

additional 3 percent per year during the 2018 attainment years where doing so is not necessary to 

attainment would be more than Congress intended to require through the RFP requirements 

under Part D of Subchapter I of the CAA Amendments of 1990. However, because a pre-2011 

baseline would be voluntarily selected by a state and would create a larger gap period before the 

attainment date than a 2011 baseline (as much as 2 to 4 years), we believe the language 

“whatever additional emissions reductions are needed for attainment” is not specific enough to 

ensure annual incremental progress through the latest attainment date. Therefore, we are 

finalizing as proposed an additional 3 percent per year as a reasonable RFP reduction 

requirement for a state that chooses to take advantage of the regulatory flexibility this regulation 

offers by selecting a pre-2011 baseline. CAA Section 171(1) defines reasonable further progress 

under Subpart D to include such annual emission reductions as “may reasonably be required by 

the Administrator for the purpose of ensuring attainment of the applicable national ambient air 

quality standard by the applicable date.” Consistent with that, the EPA concludes that it is 

reasonable to require that if a state chooses to use an earlier baseline year, its total RFP emission 

reduction obligation should be to ensure that additional reductions averaging 3 percent per year 

for each year beyond the first 6 years until the year before the attainment year are provided for in 

the RFP plan. However, the EPA continues to believe the 2011 NEI reporting year is the 

preferred baseline year for RFP planning purposes.

Comment: Design value years

Commenter (0163) opposed allowing a state to use an alternative baseline year that falls outside 

of the area's design value calculation. Commenter (0163) stated emissions reductions that fall 

outside the years in which the design value was calculated are irrelevant to the designation of the 

area and its progress towards attainment.

Response: While the situation noted by the commenter is unusual, the EPA wants to provide the 

necessary flexibility to states to prepare their attainment plans, in some cases because of the 
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resource constraints noted by other commenters. The design value used for the 2008 ozone 

nonattainment designations finalized in 2012, was gleaned either from the years of 2009-2011 or 

2010-2012. The 2008 ozone SIP requirements rule allows 2008 as an alternate baseline year 

which would be outside the design value range noted by the commenter. The EPA acknowledges 

that the commenter’s scenario may be possible and it may be likely the areas designated 

nonattainment in 2012 may have also been violating the new NAAQS with the 2008, 2009 and 

2010 design values and all of these design values reflect emissions from 2008, even though the 

area was not yet officially designated nonattainment. The EPA believes it is appropriate to credit 

any emissions reductions from SIP-adopted measures that occur in 2008 and after toward 

satisfying RFP requirements because these reductions contribute to attainment. Additionally, the 

EPA believes that this policy provides an incentive for states to achieve additional reductions 

prior to designations.

The EPA notes that states that choose to use an alternative RFP baseline are not relieved of their 

obligation to achieve a 15 percent emission reduction within 6 years. Additionally, states that 

choose an alternative baseline that comes before 2011 are required to achieve additional 

emission reductions that average out to 3 percent per year for each additional year earlier than 

2011. EPA disagrees with the Commenter’s assertion that emission reductions that fall outside 

the years in which the design value was calculated are irrelevant. One of the criteria for emission 

control programs that are made part of a SIP is that the reductions must be permanent. Therefore, 

control programs begun any number of years prior to an attainment date assist towards the area’s 

goal of reducing emissions and achieving the NAAQS. 

Comment: Baseline year multi-state agreement

Commenters (0163 and 0179) supported the multi-state proposal. However, Commenters (0144

and 0177) did not agree with the EPA’s proposal that for a multi-state nonattainment area, all 

states associated with the nonattainment area must consult and agree on the same alternate year 

to use as the baseline year for RFP. Commenter (0144) stated that, the RFP demonstration is 

state specific and does not rely on a regional inventory. Commenter (0177) provided the 

following additional points. The Commenters argued that, the CAA 182(j)(1)(A) requires multistate areas to take all reasonable steps to consult and coordinate when developing SIP plans. 

There may be reasonable and legitimate reasons justifying the use of different RFP baseline 

years by the states in a multi-state area. For example, one state may want to take RFP credit for a 

state control strategy implemented just prior to the “default” baseline year, thus justifying 

expending the additional resources needed to generate an inventory for a year outside the 

triennial emission inventory cycle. Meanwhile, another state in the multi-state area may not have 

the same motivation, instead preferring to rely on the most recent triennial inventory as the RFP 

baseline inventory. Generally, as long as each state within the multi-state area is able to 

independently demonstrate RFP for its portion of the area for the 2008 ozone NAAQS, RFP 

should be achieved in the nonattainment area as a whole, especially when the sizeable emission 

reductions expected from mobile source fleet turnover are considered. 

Response: We received mixed reactions on our proposal to have states consult and agree on the 

same baseline year when those states are associated with a multi-state nonattainment area. The 

CAA requirement to establish a “default” baseline year for a multi-state area is an area-wide 
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requirement. The EPA believes that accounting for multi-state emission reductions on an areawide basis for the same baseline year, satisfies the act. We also acknowledge that the choice of 

baseline year for a multi-state area impacts the area-wide inventories necessary for the areas and 

for nonattainment modeling that is conducted for the area. We believe that it would not make 

practical sense for the areas to have multiple different baseline years because this would impact 

attainment planning. We have finalized that for a multi-state nonattainment area, all states 

associated with the nonattainment area must consult and agree on the same year to use as the 

baseline year for RFP.

Comment: The baseline year must be 2012

Commenter (0180) stated that, the EPA’s proposal to set 2011 as the presumptive baseline year 

and further, to allow states to pick a baseline year other than 2011 for ROP purposes if 

“appropriate and justifiable” is unlawful, as it is not consistent with the statute. Commenter 

(0180) asserted that both the Supreme Court and the D.C. Circuit have made clear that the EPA 

cannot construe the Act in a way that renders nugatory subpart 2’s explicit restrictions on EPA 

discretion or that substitutes the EPA’s policy preferences for the approaches specified by 

Congress. Whitman, 531 U.S. at 484-85; SCAQMD, 472 F.3d at 894-95, 902-03. 

Commenter (0180) stated that, the EPA’s proposal to let states pick an alternative baseline year 

is also unlawful and arbitrary because it would apparently allow states to pick a baseline year 

that predates nonattainment designations, thereby allowing states to claim ROP credit for 

emission reductions that occurred before an area was even designated nonattainment, contrary to 

the approach in section 182(b)(1) of the Act. Commenter (0180) asserted, that the proposed 

approach would lead to attempts by states to game the selection of a baseline year to minimize 

the emission reductions required to satisfy the percent reduction requirements and that the 

proposed criteria for selecting an alternative baseline year are so vague and standard-less as to 

render the proposal arbitrary. 

Commenter (0180) added that, it would be particularly arbitrary to allow an area to use an older 

baseline year if that area is late in submitting its ROP plan as this would undermine the Act’s 

progress requirements by allowing the area to arbitrarily delay submission of the ROP plan and 

then, rely on reductions that occurred in the interim (due to no plan requirements or other effort 

on that area’s part) in order to provide less in the way of total emission cuts than would 

otherwise have been required. Commenter (0180) asserted that such an approach would also 

effectively allow these areas to illegally delay achievement of the 15 percent target, because the 

EPA has typically (and illegally) approved 15 percent ROP plans based on their purported 

achievement of the 15 percent reduction by the time of ROP plan approval – even if that 

approval occurs years after the 6-year period following the baseline allowed under the statute. 

Response: The EPA disagrees with the Commenters’ claim that, the CAA provides no flexibility 

in allowing a choice of a baseline year for RFP. Further, the EPA disagrees with the 

Commenter’s implication that the rule provides unlimited choice to states to choose 

inappropriate years for the choice of an RFP baseline year. The final preamble states “...a state 

has flexibility to use an alternative baseline year if it shows that the alternative year is 
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appropriate and justifiable.” The requirement that the year be “appropriate and justifiable”, along 

with the requirement that the EPA approve attainment plans, allows the EPA to ensure that 

inappropriate years will not be used. To clarify the intent of the “appropriate and justifiable” 

wording, the EPA has further added the explanation to the rule that says, “The inventory should 

be representative of the emission source contributors understood to have resulted in a 

nonattainment designation for the area.”

The EPA disagrees with the Commenter’s assertion that 2012 must be the base year for RFP 

plans for consistency with the timeframes within the 1990 amendments to the CAA because it 

overlooks a critical aspect of emission inventory development and updating prescribed by this 

law. In addition to requiring a base year emissions inventory, the 1990 amendments to the CAA 

set in place a requirement for periodic updates to the base year inventory on a 3 year cycle, 

beginning with 1993. Since that time, most states have prepared emission estimates of stationary 

and mobile sources on a 3 year cycle, and the EPA has made this a regulatory obligation for all 

states within its Air Emissions Reporting Rule (AERR). 

The EPA disagrees with the Commenter’s claim that 2012 is the only viable year for an RFP 

baseline. The EPA has flexibility in determining how to interpret provisions of the statute for 

purposes of implementing the 2008 ozone NAAQS. Nothing in the statute explicitly or implicitly 

suggests that all areas must use the same baseline year. The purpose of the RFP requirement is to 

ensure areas achieve percentage reductions in emissions that will help an area attain the NAAQS 

and to not delay emission reductions until close to the attainment date. Thus, we believe a 

baseline year that is reasonably close to the designation date and within the implementation 

timeframe of the revised NAAQS will ensure that the goal of the RFP provisions is met. We note 

also, that regardless of the baseline year selected, the final regulations provide that areas must 

continue to achieve annual percentage reductions up to the attainment year. This will further 

ensure that the purpose of the RFP provisions is fulfilled. We do not believe it is reasonable to 

select a baseline year for RFP purposes that predates both the revisions to the NAAQS in 2008 

and nonattainment designations. 

We disagree with the Commenter’s assertion that by allowing alternative selections for the 

choice of a base year, we are awarding states RFP credit for emission reductions that occurred 

before an area was designated nonattainment. We received support from commenters that 2011 

would be an appropriate baseline year while other Commenters urged, the EPA to allow the 

option of justifying an alternative baseline year, including 2012, 2008, 2007 and 1990. In 

determining the appropriate alternate years, the EPA recognizes that some states may have 

initiated certain control strategies between the year the standard was finalized (2008) and the 

most recently available triennial emission inventory year (2011) and that, it would be appropriate 

to recognize these investments in implementing early reductions to achieve improved air quality. 

We also believe that allowing alternate baseline years prior to 2008 (e.g., 1990 and 2007) would 

not be appropriate because we believe that it is necessary for RFP credit for attainment planning 

to be tied as directly as possible to promulgation of the 2008 ozone NAAQS. Emission reduction 

measures adopted into the SIP prior to promulgation of the 2008 NAAQS are certainly helpful 

for improving air quality and consequently, may lower the nonattainment classification of an 

area, but are not readily tied to attainment planning for a specific standard and the associated 
83

nonattainment designation that did not yet exist and therefore, are not appropriate to be credited 

for fulfilling nonattainment area RFP requirements. We also recognize that since we designated 

most areas on April 30, 2012, with an effective date 60 days after publication in the FR, that 

2012 (the designation year) is an appropriate alternative baseline year consistent with the subpart 

2 structure. With these considerations, the EPA is finalizing that states may use an alternate year 

(i.e., other than 2011) between the years of 2008 to 2012 that the state justifies as appropriate. 

We provide this incentive and remind commenters that this flexibility in choosing a baseline year

is tempered by a 3 percent addition that we believe is necessary to ensure the CAA’s requirement 

of progress is nonetheless.

The EPA disagrees with the Commenter’s contention that allowing states to specify an 

alternative RFP baseline is arbitrary and that the criteria for states to justify an appropriate year 

are vague and arbitrary. The EPA’s approach for allowing states to select and justify an 

appropriate alternate baseline year is the same RFP SIP requirement we established for the 1997 

ozone standard, and we refer the Commenter to our more detailed treatment of this topic in 

materials developed for that standard, such as our November 29, 2005 final implementation rule 

(See 70 FR 71637).

The EPA disagrees with the Commenter’s contention that the EPA should not approve RFP plans 

that demonstrate the RFP milestone has been achieved, but was not achieved by the relevant 

milestone date. First and foremost, the EPA only approves RFP plans that comply with the Clean 

Air Act. Secondly, we believe that once a statutory deadline has passed and has not been 

replaced by a later one, it is reasonable to require the plan to comply with the act “as soon as 

possible.” See Delaney v. EPA, 898, F.2d 687, 691 (9th Circuit, 1990). EPA has interpreted this 

requirement to be “as soon as practicable.” Therefore, in some instances the EPA may determine 

that circumstances surrounding the delayed achievement of RFP reductions merit approval of a 

plan demonstrating delayed achievement of the RFP milestone, and that, this is a more 

appropriate course of action than disapproval of an original plan that did not meet this 

requirement. The EPA evaluates such actions on a case by case basis, and only approves such 

actions after a public notice and comment period has been offered.

Comment: Support for credit from SIP and federally promulgated measures 

Commenters (0159, 0161and 0179) supported the proposal that, emission reductions resulting 

from SIP approved or federally promulgated measures occurring after the baseline emissions 

inventory year would be creditable toward RFP requirements, provided that the reductions are 

enforceable, quantifiable, permanent and surplus. Commenter (0159) noted that, this 

interpretation has been adopted by the EPA in the past, most notably during the process of 

implementing the 1997 ozone NAAQS, and such approach is required under federal regulations, 

40 C.F.R. § 51.910(a)(2). Commenter (0161) argued that, there is no reason to disallow RFP 

credit for reductions simply because they were required by the EPA. These are significant 

reductions that clearly will result in progress toward NAAQS attainment. It would be 

inappropriate to require sources to comply with these new controls but then to withhold RFP 

credit for the air quality improvements that will result therefrom. The EPA has authority under 

the CAA to allow states to credit SIP-approved and federally promulgated reductions toward 
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RFP requirements. In 42 U.S.C. §751la(b)(l)(D), Congress listed the emissions reductions that 

are not creditable toward RFP requirements. Because Congress specifically set forth those 

reductions that it believed were inappropriate to credit toward fulfillment of RFP requirements, 

its failure to exclude other reductions, such as those contemplated by the EPA in this rulemaking, 

shows that Congress did not intend to prevent states from taking RFP credit for such reductions 

[See TVA v. Hill, 437 U.S. 153, 188 (1978)]. Allowing RFP credit for federally required 

reductions would be within the EPA's authority and would appropriately recognize the air quality 

improvements that are being achieved through controls such as those contained in the new NSPS 

for oil and gas sources. 

Response: In the final rule, the EPA is allowing states to credit federally required reductions, 

occurring within the nonattainment area and that aligns with the requirements of sections 182(b) 

and 182(c). The EPA believes that Congress did not intend to prevent states from taking RFP 

credit for these reductions because Congress specifically set forth reductions that were deemed 

inappropriate to credit toward fulfillment of RFP requirements and no other reductions have been 

set forth.

Comment: Baseline inventory for RFP should be a high ozone summer day

Commenters (0144, 0146 and 0167) stated that, the EPA should include the requirement in the 

rule that the baseline inventory for RFP and contingency measures should be a high ozone 

summer day, rather than an annual inventory. Together, these Commenters stated that, the 

current inventory guidance is inconsistent: the ozone rule proposal and background section 

references the air emissions reporting requirements (AERR) for the purposes of defining the data 

elements for the emissions inventories for ozone relevant data element requirements, but the 

simultaneous AERR proposed amendments are removing the ozone related definitions and 

guidance; further, the background section of the ozone rule also references the EPA August 2005 

inventory guidance document, but this 2005 guidance document references and includes the 

consolidated emissions reporting rule (CERR), which no longer exists. 

Commenter (0146) stated, specificity was expressed in the previous ozone implementation rule 

as follows: “Consistent with the manner in which [ROP] plans under the 1-hour ozone standard 

were developed, the RFP baseline for 2002 will have a typical summer day tons/day basis. As 

such, the attainment year target will also be a typical summer day target.” Commenter (0146) 

stated, if the intent of the language in the proposal was to allow such elements to be based on 

annual inventories, then the EPA is misguided; if this is instead an error of omission, then the 

EPA must clarify the requirements with language consistent with that used previously. 

Response: The EPA concurs that the current inventory guidance is outdated. The EPA intends to 

provide updated draft inventory guidance early in 2015 that reflects the updated AERR final rule, 
85

signed by the Administrator on February 6, 2015,15 and other developments occurring since the 

2005 version of that guidance. The guidance will define all data fields relevant for ozone 

attainment plans, including the ozone season day emissions fields that will be required for ozone 

attainment plan emission inventories. 

The EPA will also modify the language of the rule to reflect “ozone-season day” emissions 

rather than “summer-day” emissions, since not all ozone exceedances occur in the months 

commonly referred to as “summer.” In fact, some area violations occur in the winter season 

under very specific conditions.

The EPA concurs with the comment that this rule needs to clarify that ozone season day 

emissions are required for proper implementation of the ozone NAAQS. The EPA does not 

concur that “high” ozone season day is necessary in all cases, and so the final rule allows states 

to work with their regional offices to define the days included in the ozone-season day emissions 

calculation. The purpose of this latitude is for states to create emissions that will be appropriately 

representative of the ozone problem for their nonattainment area(s). While the EPA has removed 

the requirement to report daily and seasonal emissions in the AERR final rule, signed by the 

Administrator on February 6, 2015, the ozone season day emissions will be required as part of 

the ozone implementation rule. The final rule has been updated to reflect that proper wording.

7. Emissions outside the nonattainment area

Comments: Supporting EPA’s proposed approach for RFP

Commenters (0159 and 0163) noted that, the EPA's proposed approach is legally correct, insofar 

as it applies to RFP. Commenter (0146) stated that, the majority of NESCAUM states generally 

oppose allowing RFP credit for emissions reductions that occur outside of the nonattainment area 

(78 FR 34191), on the grounds that RFP reductions tie back to baseline emissions described in 

section 182(b)(1)(B) of the CAA, which references emissions “in the area.” Commenter (0161) 

stated that, nonattainment areas seeking reductions needed to fulfill RFP requirements should 

obtain those reductions from sources located within the nonattainment area, not from sources 

outside the nonattainment area. Commenter (0180) stated that, the EPA correctly proposes that 

states may not take credit for VOC or NOx reductions occurring outside the nonattainment area 

for purposes of meeting the 15 percent and 3 percent ROP requirements. The Commenter stated 

that, allowing credit for outside the area reductions is contrary to the Act as construed by the 

D.C. Circuit Court. The Commenter also believed that, the EPA’s solicitation of comments on 

whether there is clean legal rational for allowing credit for reductions outside the nonattainment 

area to satisfy the RFP requirements for the 2008 ozone NAAQS was nonsensical. 

Commenter (0146) stated that, the majority of NESCAUM states generally oppose allowing RFP 

 

15 AERR Final Rule signed by the Administrator on February 6, 2015 is available at: 

http://www.epa.gov/ttn/chief/aerr/final_rule_preamble.pdf
86

credit for emissions reductions that occur outside of the nonattainment area (78 FR 34191), on 

the grounds that RFP reductions tie back to baseline emissions described in section 182(b)(1)(B) 

of the CAA, which references emissions “in the area.” 

Commenter (0163) maintained that the RFP provisions specify the minimum level of reductions 

required in the area. The CAA section 182(b)(1)(A)(ii) details what an area must do to obtain 

less than the minimum (15 percent) reduction. In addition, CAA section 107(d)(l)(A)(i) states 

that the nonattainment area would be any area that does not meet (or that contributes to ambient 

air quality in a nearby area that does not meet) the NAAQS. Taken together, it is clear that the 

RFP reductions need to be from the nonattainment area. 

Commenter (0180) opposed RFP credit for emissions outside the nonattainment and stated that, 

allowing credit for such “outside” reductions is contrary to the Act (citing NRDC, 571 F.3d at 

1256). Commenter (0180) asserted that, the agency says it believes “there may be cases where 

the most beneficial and cost-effective reductions are from sources located outside the 

nonattainment area boundaries,” See id., but even if that is true, it cannot override Congress’ 

specification that the reductions to satisfy the percentage ROP requirements must come from 

within the nonattainment area.

Response: The EPA appreciates the Commenters’ comments in support of the proposed 

approach that, states may not take credit for emissions reductions from outside the nonattainment 

area for purposes of meeting the ROP/RFP requirements under sections 182(b) and 182(c). The 

EPA generally agrees with the supporting comments and, for the reasons outlined in the proposal 

and in light of supporting comments, is finalizing the proposed approach.

Comments: Opposing EPA’s proposed approach for RFP – Legal Rationale Comments

Commenter (0140) recommended that, the EPA allow states to use areas outside of the 

boundaries of the nonattainment area yet within the Air Quality Control Region (AQCR), which 

are already part of a SIP and supposedly represent the “airshed” for a given area, to credit 

emission reductions toward satisfying RFP. The Commenter (0140) stated that, restricting RFP 

emission reductions to the boundaries of the nonattainment area is not a reasonable interpretation 

of the statute for NOx-limited areas and where ozone transport typically accounts for well more 

than half of an area’s ozone levels on high ozone days. The Commenter recommended, that the 

EPA allow states to use the entire AQCR (or AQCRs if the boundaries cross AQCR boundaries) 

in which a nonattainment area is located to set the baseline and target emission levels; and to 

allow states to also include in the baseline and target emission levels an adjacent AQCR if 

modeling demonstrates that emissions from that AQCR are causing an average contribution of 

over 0.75 ppb or over 0.99 ppb to ozone standard violations within the nonattainment area. 

Commenter (0140) argued that, the authority for allowing emission reductions within an AQCR 

can be found in section 107(c) of the CAA, which states that the Administrator designates as an 

air quality control region “any interstate or intrastate area which he deems necessary or 

appropriate for the attainment and maintenance of ambient air quality standards.” The 

Commenter stated that, since these regions are formally adopted as part of the SIP, they represent 

meaningful boundaries that are “necessary” or “appropriate” for the attainment of any air quality 
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standard, including the 2008 ozone NAAQS. The Commenter further stated that, the language in 

this section does not indicate that just because a smaller geographic area within an air quality 

control region is designated as nonattainment for a specific pollutant, emission reductions 

elsewhere within the air quality control region are not also “necessary” or “appropriate” for 

making RFP towards attainment of a standard within the nonattainment area. The Commenter 

suggested that, a legal basis for an even broader geographic area can be found in the definition of 

“RFP” in section 171(1). The Commenter argued that, there is no mention of the emission 

reductions being restricted to only the boundaries of the nonattainment area, and indeed, this 

language would presumably require emission reductions from outside of the nonattainment area 

if those emission reductions were used by the state to demonstrate “such annual incremental 

reductions in emissions of the relevant air pollutant as are required by this part or may 

reasonably be required by the Administrator for the purpose of ensuring attainment of the 

applicable national ambient air quality standard by the applicable date.” The Commenter

similarly believed that, section 182(b)(1)(A)(i) does not specifically require that the emission 

reductions occur within the boundaries of a designated nonattainment area, but rather that “such 

plan shall provide for such specific annual reductions in emissions of VOC and NOX as 

necessary to attain the national ambient air quality standard for ozone by the attainment date 

applicable under this act.” Commenter (0151) believed that, it would be good policy to allow 

outside the area reduction credits toward satisfying RFP, even if the emissions are not in a state’s 

emission inventory and the Commenter believed that, the CAA section 110(h) supported this 

policy. The Commenter further stated that, since this rule would already allow states to take 

credit under EPA’s transport modeling for upwind reductions under state and other federal CAA 

measures (e.g., auto standards, NSPS and maximum achievable control technology (MACT) 

requiring VOC and NOx reductions outside the state, it seems that the legal theory is already in 

place to credit upwind reductions. 

Commenters (0139, 0148, 0150 and 0160) supported allowing nonattainment areas to take RFP 

credit for emission reductions that occur in upwind areas and suggested consideration of a 

“transport couples” approach. Specifically, one Commenter (0139) recommended that, the EPA 

redefine the term “area” for purposes of the RFP requirement. The term “area” should be 

considered to include the entirety of the “transport couple” area. Commenter (0148) urged, the 

EPA to continue allowing nonattainment areas to take RFP credit for emission reductions that 

occur in upwind areas, especially in cases where it can be shown that: 1) emissions from 

transport are contributing to the nonattainment status of the downwind area; and, 2) an area 

included emission increases as well as reductions from outside the nonattainment area in its RFP 

calculations. The Commenter specifically indicated, the consequences of being adjacent to the 

State of California’s South Coast Air Basin that transports air pollution that contributes to ozone 

violations in the downwind area. The Commenter added that, air pollutants from the South Coast 

Air Basin are periodically blown offshore then carried to the coastal cities of Ventura County 

and further inland. The Commenter further stated that, South Coast air pollutants can also affect 

a downwind area by way of a direct inland route from the San Fernando Valley during periods 

when winds blow from the east. Conversely, and not surprisingly, Ventura County emissions can 

affect ozone levels in the South Coast Air Basin when winds blow air pollutants from the our 

coastal areas, eastward into the San Fernando and Santa Clara River Valleys, thereby 

contributing to elevated ozone there. The Commenter continued to point out that, pollutant 
88

transport among areas in Southern California is well documented by the California Air 

Resources Board and is the primary reason for including most of Southern California in the 1997 

Southern California Ozone Study (SCOS) modeling domain used for the Southern California 

components of California's 8-hour ozone SIP. The Commenter stated that, other ozone 

nonattainment areas in California and the country are similarly interconnected through air 

pollutant transport couples. The Commenter further stated that, many of these areas are 

nonattainment largely because of transport from nearby upwind areas and could therefore find 

demonstrating RFP a great challenge. The Commenter believed that, given that many 

nonattainment areas are affected by transported air pollutants, it is technically sound and good 

public policy to allow emission reductions generated in one area to be counted towards RFP in 

adjoining areas in cases where such pollutant transport relationships between the areas have been 

verified. Commenter (0139) also stated that, in the case of RFP, the demonstration is intended to 

be a collective “area” demonstration and that by allowing outside area reductions to be included, 

the EPA would be authorizing additional area emissions to be included and subject to the 15 

percent RFP obligation if the emissions meet certain other criteria (the additional areas must be 

Moderate or above classification and contribute to attaining the standards).

Commenter (0150) noted that, unlike the definition of RACT involved in the NRDC case, there 

is no express requirement that RFP reductions come from within the "area." The Court in NRDC 

relied on specific statutory language requiring nonattainment plans to include: "The 

implementation of all RACM as expeditiously as practicable (including such reductions from 

existing sources in the area as may be obtained through the adoption, at a minimum, of RACT) 

.... " The Commenter believed, the Court ruled that the CAA expressly required RACT to be 

imposed on existing sources in the area; the requirement could not be satisfied by obtaining 

equivalent or greater reductions from outside the area. In contrast, there is not language expressly 

requiring that RFP must be obtained from sources "in the area." The basic definition of RACT is: 

such annual incremental reductions in emissions of the relevant air pollutant as are required by 

this part or may reasonably be required by the Administrator for the purpose of ensuring 

attainment of the applicable national ambient air quality standard by the applicable date. CAA § 

171(1); 42 U.S.C. §7501(1). The Commenter further stated that, with regard to ozone, there are 

two different RFP requirements. The Commenters stated that, first, the plan must provide for 

VOC emission reductions, within 6 years, of "at least 15 percent from baseline emissions." § 

182(b)(l)(A); 42 U.S.C. § 7511a(b)(1)(A). The Commenter stated that, second, the plan must 

"provide for such specific annual reductions in emissions of VOC and NOX as necessary to attain 

the national ambient air quality standards (NAAQS) by the attainment date..." The Commenter 

indicated that, neither requirement contains the term "in the area." The Commenter stated that, 

since the EPA agrees that areas can rely on upwind reductions for attainment, 78 FR 34101 col. 

2, the EPA has the flexibility to set the targets for the second RFP requirement at whatever levels 

will allow attainment, taking into consideration the reductions occurring in upwind areas. The 

Commenter concluded that, the second requirement may be administered in a reasonable manner 

even if all the reductions are required to come from inside the area. The Commenter further 

stated that, the only basis for any concern that reductions must come from within the 

nonattainment area is the fact that the term "baseline emissions," from which the plan must 

reduce emissions by 15 percent in the first RFP requirement, is defined to mean "the total 

amount of actual VOC or NOx emissions from all anthropogenic sources in the area during the 
89

calendar year 1990..." § 182(b)(l)(B); 42 U.S.C.; § 7511a(b)(1)(B). The Commenter pointed out 

that, this is the only sense in which the term "in the area" is used in the RFP provisions of the 

Act. The Commenter argued that, if the reductions are calculated from a baseline that includes 

only emissions "in the area" the reductions must also come from within the area. Of course, the 

Act does not expressly so state. But even assuming this conclusion is correct, EPA has the 

flexibility to interpret the term "in the area" to allow for the concept of the "transport couple 

area" discussed above. Commenter (0139) also recommended that, the EPA redefine the term 

“area” for purposes of the RFP requirement and that the term “area” should be considered to 

include the entirety of the “transport couple” area. Commenter (0139) provided the following 

additional statements on the legal rationale for allowing out-of-area reductions to be counted 

toward the 15 percent RFP. 

Commenter (0139) understood that, section 182(b) uses both the terms “in the nonattainment 

area” at section 182(b)(1)(A)(ii)(I) and “in the area” at section 182(b)(1)(B). The Commenter 

added that, section 182(b)(1)(B) does not so restrictively define the term “in the area” as to mean 

just the particular nonattainment area of interest. In fact, with respect to RFP, it does not 

explicitly define the term at all. It merely says “in the area” without defining the geographical 

boundaries of the “area.” The Commenter concluded that, the intent of this section is to allow a 

larger area than the subject nonattainment area based on the specific air quality circumstances in 

question and that the EPA does have authority to interpret the term to mean two or more 

geographic areas for which emission transport couples have been established. Such areas could 

be considered one area for purposes of both central RFP requirements of section 182(b)(1)(A), 

the 15 percent from baseline requirement, and the annual reductions in emissions for timely 

attainment requirement, provided that there are enforceable mechanisms in place to guarantee 

that the upwind emissions actually occur. Doing so would establish consistency between these 

two RFP mandates and help areas meet their RFP obligations more cost-effectively than the 

EPA’s current RFP proposal. 

Commenter (0166) stated that, RACT by definition refers to sources “in the area,” The CAA § 

172(c)(1), and the D.C. Circuit in NRDC v. EPA latched onto that language, confirming that 

areas cannot go outside their boundaries for RACT purposes. However, the case did not address 

RFP requirements in this regard, so it does not control here. Furthermore, the statutory 

provisions addressing RFP do not explicitly state that such reductions must in all cases take place 

within the area. See CAA §§ 172(c)(2), 182(b)(1). The Commenter added that, to the extent a 

nonattainment area does seek credit for RFP purposes with respect to emission reductions 

occurring outside the area, though, the state should also expand the emissions inventory 

establishing the baseline by covering the area being used for RFP purposes. The Commenter 

further believed, if the EPA takes this approach, it must be prepared to disallow NOx-for-VOC 

emission reduction substitutions where they are not appropriate or justified, such as in core urban 

areas. The Commenter maintained that, in core urban areas, VOC emission reductions are 

demonstrably more effective and therefore, it would be inappropriate to substitute NOx emission 

reductions outside the core urban area for VOC emission reductions inside the core urban area.

Commenter (0150) pointed toward the D.C. Circuit Court of Appeals recent decision that, 

although there is a presumption that a term appearing in several places in a statute is to be read 
90

the same way each time, the presumption "readily yields" based on differences in the context in 

which the words are used. Coalition for Responsible Regulation v. EPA, 684 F.3d 102, 142(D.C. 

Cir. 2012). The Commenter believed, that the Court in that case interpreted a similar term: "in 

any area to which this part applies." Id. The Commenter further argued, that moreover, words 

that can have more than one meaning are given content by their context. Whitman, supra, 531 

U.S. at 466. The Commenter concluded that, in this case, the EPA would be justified in treating 

the language relative to RFP differently from the way it treat as the language relative to RACT, 

because by definition, it is possible for all sources in a downwind area to comply with RACT. 

The Commenter believed that, this is because RACT is defined as "the lowest emission 

limitation that a particular source is capable of meeting by the application of control technology 

that is reasonably available considering technological and economic feasibility." 44 FR 53762 

(Sept. 17, 1979). In contrast, it may not be possible for a downwind area to attain the 15 percent 

reduction. Even though the sources are fewer in the downwind area, and thus, the 15 percent 

target is smaller, if the sources are primarily mobile sources, such as in the Coachella Valley, and 

the area has no ability to reduce emissions from those sources, it may not be possible to attain the 

15 percent. The Commenter concluded, that in this case, the EPA could use the term "in the area" 

when referring to "baseline emissions" for RFP purposes to refer to a "transport couple area." 

The Commenter believed that, as noted earlier, this approach addresses the concerns the 

environmental group expressed about the EPA's earlier approach and is consistent with the intent 

and purpose of the RFP requirement. The Commenter believed that, a literal interpretation of the 

term "in the area" as proposed by the EPA could produce absurd results. Such an interpretation 

would require the EPA to disapprove a plan based on failure of the downwind area to have 15 

percent reductions "in the area" even if the plan provides for (1) more than 15 percent reductions 

in total pollution in the area; (2) more than 15 percent emission reductions within the ''transport 

couple area"; and (3) attainment on or before the required date. EPA may rely on the concept of 

"absurd consequences" to avoid even a "plain meaning" of a statute; thus, it may certainly rely on 

such consequences to allow it to use the concept of "transport couple area" as being the "area" 

referred to in the definition of baseline emissions for RFP purposes. See EPA's discussion in the 

GHG Tailoring Rule, 75 FR 31514 (June 3, 2010). 

Commenter (0161) stated their belief that states should not step outside the boundaries of 

nonattainment areas to achieve emission reductions to satisfy RFP requirements. The Commenter 

maintained that, the CAA provides that, with certain listed exceptions, emissions reductions are 

creditable toward RFP requirements to the extent that the reductions resulted from 

implementation of measures required under the applicable implementation plan, EPA rules, or a 

Title V permit. 42 U.S.C. § 7511a(b)(I)(C). The Commenter stated that, the listed exceptions do 

not pertain to out-of-area reductions. 42 U.S.C. § 7511a(b)(l)(D)(i-iv). The Commenter further 

stated that, because the CAA contains no exception that would disallow credit for out-of-area 

reductions, the EPA has discretion to allow states to credit out-of-area emissions reductions 

toward fulfillment of RFP requirements. 

The Commenter stated that, the EPA would be incorrect to apply this holding to the present 

rulemaking, however, because the holding is limited to specific the CAA language regarding 

RACT requirements. The Commenter believed that, the CAA unambiguously requires that a SIP 

provide for "reductions in emissions from existing sources in the area" as may be obtained 
91

through the adoption of RACT, and the Court's decision followed directly from this 

congressional directive in CAA section 182(c)(l). The Commenter believed that, the Court’s 

holding does not pertain to RFP requirements and it, therefore, has no bearing on the way that 

RFP requirements are to be interpreted or applied. The Commenter concluded that, the EPA 

should not view NRDC v. EPA as expressing any limit on the agency's authority to allow RFP 

credit for out-of-area reductions. The Commenter further stated, their belief that Congress did 

not intend to prohibit RFP credit for out-of-area reductions is also shown by the language that it 

used in CAA section 172(c), where general nonattainment plan provisions are set forth. The 

Commenter stated that, it has been noted before that the RACT provision set forth at section 

172(c)(l) specifically requires reductions from sources "in the area." But in the subsection that 

immediately follows, section 172(c)(2), the RFP provision is set forth and it states merely that 

"plan provisions shall require RFP, section 172(c)(2)] with no "in the area" limitation. The 

Commenter believed that, Congress knew how to limit SIP requirements to in-area sources when 

it wanted to, as it did in the RACT provision in subsection (c)(l). The fact that it chose not to 

engraft such limiting language in the RFP provision in subsection 172(c)(2) is further indication 

that Congress did not intend to prevent states from crediting out-of-area reductions toward RFP 

targets. [See Russello v. U.S., 464 U.S. 16, 23 (1983).] The Commenter also considered it 

significant that, the CAA lists four specific types of emissions reductions under section 

182(b)(1)(D)(i)-(iv) that are not creditable toward fulfillment of RFP goals and that Congress 

could have included reductions from out-of-area sources among these non-creditable reductions, 

but it did not do so. The Commenter concluded that, if Congress had intended to disallow credits 

from outside the nonattainment area, it could have expressly disallowed it as it did for RFP credit 

for four other specific categories of emission reductions

Commenter (0151) believed that, the “inside the area” limitation comes from the definition of 

“baseline inventory” in CAA section 182(b)(1)(B). Therefore, the commenter supported the 

EPA’s earlier rulemaking, never completed, that allowed states to add these sources outside of 

the state to their emission inventory. The Commenter stated that, the question, then, could morph 

into whether addition of the source for which credit is being taken to the emission inventory 

triggers additional RFP, if a state’s original plan was approved. The Commenter did not believe 

that, additional RFP measures are required in an expanded nonattainment area.

Response: In the proposed SIP Requirements Rule, 78 FR at 34191, we proposed that “. . . 

.states may not take credit for VOC or NOx reductions occurring outside the nonattainment area 

for purposes of meeting the 15 percent and 3 percent RFP requirements of sections 172(c)(2), 

182(b)(1) and (c)(2)(B).” This approach means that ROP credit for meeting the 15 percent VOC 

requirement for Moderate and above ozone nonattainment areas in section 182(b)(1) and the 

additional 3 percent per year RFP requirement for Serious and above ozone nonattainment areas 

in section 182(c)(2)(B) can come only from emissions reductions from within the nonattainment 

area. In the preamble to the proposal, the EPA noted that it would be sound policy to allow areas 

to use outside the area reductions to meet RFP requirements, but concluded that in light of 

NRDC v. EPA, 571 F.3d 1545 and the language of the CAA there is no legal basis for allowing 

credit for emissions reductions outside the nonattainment area for satisfying ROP/RFP 

requirements. In the proposed rule, we also stated that, if the EPA received comment providing a 

clear legal justification for this approach, we would consider including this approach in the final 
92

rule. We received several comments supporting this approach, including suggested legal 

arguments, but after carefully considering them, we have concluded that no comment provided a 

persuasive legal rationale for that approach and therefore, are finalizing the approach outlined in 

the proposal of not allowing out of area credit. 

The RFP requirements in CAA 182(b)(1)(A)(i) and 182(c)(2)(B) require that nonattainment SIPs 

provide for emission reductions from “baseline emissions.” And CAA section 182(b)(1)(B) 

defines baseline emissions as “the total amount of actual VOC or NOx emissions from all 

anthropogenic sources in the area.” The RFP language in 182(b)(1)(B) and 182(c)(2)(B) is 

almost identical to the language in the CAA’s RACT provision that the D.C. Circuit held 

required that reductions come from within the nonattainment area and not “from sources outside 

the nonattainment area.” NRDC v. EPA, 571 F.3d at 1256. Accordingly, EPA has concluded that 

it has no legal basis for allowing credits for reductions outside the nonattainment area. 

Comment: Suggestions that would allow out of area reductions

Commenters suggested various mechanisms and rationales for allowing out of area reductions. 

Some suggested allowing credit for emission reductions from an area larger than the 

nonattainment area but related to or affecting it, such as the same airshed or an air quality control 

region or a “transport couple area.” These comments emphasized the close connection between 

air quality within the nonattainment area and emissions from outside that area but within the 

larger unit proposed for consideration. The Commenters also argued that, controlling emissions 

from outside a nonattainment area may be a very effective way to of improving air quality within 

that area and that statutory references to “the area” do not necessarily refer only to the 

“nonattainment area.” To some extent, these comments were either policy arguments in support 

of allowing out of area credits, or suggestions about how best to implement a program allowing 

such credits. But, upon examination, they did not provide a legal rationale that, in light of the 

language of the statute and the reasoning in NRDC, would support doing so. 

Another Commenter suggested that, the CAA section 107(c) provides the EPA the authority to 

allow outside the area reduction credits for satisfying RFP requirement. The EPA disagrees with 

this rationale because CAA section 107(c) enables EPA to designate air quality control 

“regions,” as necessary or appropriate for the attainment or maintenance of NAAQS. That 

process is distinct from and has no effect on the legal requirement to designate nonattainment 

“areas” and develop SIPs providing RFP toward attainment in those areas. As already noted, 

RFP requires reduction from baseline emissions in the nonattainment area. 

Commenters also argued that, requirements for reductions from “the area” do not necessarily 

require reductions from within the nonattainment area. The EPA disagrees with this reasoning 

because, as noted sections 182(b)(1)(B) and 182(c)(2)(B) require reductions “from baseline 

emissions,” and baseline emissions come from sources “in the area.” EPA does not believe it 

would be plausible to argue some references to “the area” in section 182, which deals with SIPs 

for nonattainment areas, do not refer to nonattainment areas, or that some uses of the term have 

that limitation but that others do not. Moreover, the D.C. Circuit’s interpretation of virtually 

identical language referring to the “area” in NRDC as referring to the nonattainment area for 
93

RACT, confirms that the RFP language refers to nonattainment areas. 

Another Commenter suggested that, the CAA section 110(h) provided for crediting measures 

outside the ozone nonattainment area toward attainment. The Commenter did not suggest any 

basis for this argument, and we are not convinced that our policy as stated in the final rule is 

influenced by section 110(h), and we are also not convinced that this rule provides the necessary 

legal support for allowing out of area reduction credits to satisfy RFP requirements. 

Another argument some Commenters suggested for not construing references to “the area” as 

applying to the nonattainment area is that NRDC, and thus, the decision’s reasoning, is only 

relevant to RACT and does not necessarily apply to RFP. The NRDC v. EPA decision construed 

“reductions in emissions from existing sources in the area” to refer to sources in the 

nonattainment area for purposes of meeting RACT nonattainment SIP requirements under CAA 

172(c)(1). The comment necessarily argues that nevertheless the RFP nonattainment SIP 

requirement for reductions from “baseline emissions,” CAA 182(b)(1)(A)(i) and 182 (c)(2)(B) 

which CAA 182 ((b)(1)(B) defines as emissions from “sources in the area” does not refer to 

sources in the nonattainment area. The EPA does not believe it is plausible to argue that the same 

words, “sources in the area,” applied in the same context, nonattainment SIP requirements, can 

have different meanings such that RACT applies to reductions from sources in the nonattainment 

area but the RFP applies to reductions from sources outside the nonattainment area. 

The EPA requested comment on whether there is a defensible legal rationale for allowing credits 

for out of area reductions. We did not receive any comments that provide a viable legal rationale 

for doing so, and therefore, we are not including the approach to allow areas to credit “outside 

the area” emissions reductions for ROP/RFP fulfillment. None of the comments we received 

persuaded us that the reasoning in the “background” section of the preamble was incorrect or that 

the reasoning in NRDC regarding RACT does not apply to RFP, or that some other defensible 

reading of the statute is possible. Therefore, the EPA is finalizing the interpretation that states 

may not take credit for VOC or NOx reductions occurring from sources outside the 

nonattainment area for purposes of meeting the 15 percent ROP and 3 percent RFP requirements 

of sections 172(c)(2), 182(b)(1) and (c)(2)(B). This approach means that ROP credit for meeting 

the 15 percent VOC requirement for Moderate and above ozone nonattainment areas in section 

182(b)(1), and the additional 3 percent per year RFP requirement for Serious and above ozone 

nonattainment areas in section 182(c)(2)(B), or for meeting the RFP requirement of section 

172(c)(2) for Moderate areas that met the 15 percent requirement for a previous NAAQS can 

come only from emissions reductions from sources located within the nonattainment area.

Commenters (0129, 0139, 0140, 0141, 0148, 0149, 0150, 0151, 0152, 0153, 0160, 0169, 0172, 

0175 and 0179) generally supported consideration of emissions reductions outside a 

nonattainment areas stating that, the EPA should allow states to consider reductions from 

transport sources when calculating RFP reductions if the baseline similarly includes 

contributions from transport sources. Commenters also agreed with the EPA’s assessment that, 

there may be cases where the most beneficial and cost-effective reductions are from sources 

located outside the nonattainment area boundaries and, in such cases, it would be good policy to 

credit the emission reductions toward meeting RFP requirements. Generally, Commenters urged, 
94

the EPA not to act as though nonattainment areas are isolated from adjacent areas and not 

impacted by emissions and emission reductions in neighboring areas. Commenter (0166) stated 

that, RACT by definition refers to sources “in the area,” CAA § 172(c)(1), and the D.C. Circuit 

in NRDC v. EPA latched onto that language, confirming that areas cannot go outside their 

boundaries for RACT purposes but did not address RFP requirements in this regard. Commenter 

(0146) stated that, the NESCAUM states would support providing some RFP credit for energy 

efficiency and renewable energy (EE/RE) measures instituted in the nonattainment area but 

whose reductions may not necessarily occur in that area. Commenter (0169) stated that, allowing 

RFP credits for out-of nonattainment-area sources is consistent with EPA's Roadmap for 

Incorporating Energy Efficiency/Renewable Energy Policies and Programs into State and Tribal 

Implementation Plans ("Roadmap" page 15 and 16) which is referenced throughout the proposed 

SIPs Requirements Rule.

Commenters (0146, 0163 and 0168) generally stated that, if emissions reductions necessary for 

RFP and attainment were to come from a nearby area, then the nonattainment area should be 

expanded to include that area and all of its emissions in the baseline.

Commenter (0146) stated, the NESCAUM states would, however, support providing some RFP 

credit for energy efficiency and renewable energy (EE/RE) measures instituted in the 

nonattainment area but whose reductions may not necessarily occur in that area. Commenter 

(0146) stated, this support is conditioned on the availability of sound evidence that: (1) those 

measures would produce public health benefits; and (2) the approach does not conflict with the 

CAA.

Response: The EPA appreciates the Commenters’ suggestions. The EPA continues to recognize 

that emissions of ozone precursors can impact wide geographic areas. In some cases observed 

concentrations of ozone arise predominantly from sources within the nonattainment area while in 

other cases, ozone concentrations in one particular area may be influenced by sources across a 

broad area extending outside a particular nonattainment area. The EPA recognizes that ozone 

travels over long distances, and that, distant emissions of ozone can influence area’s air quality. 

An area may be classified nonattainment in large part due to distant sources impacting the area. 

The EPA’s past procedures for addressing these situations was to allow emission reductions, 

originating at distant emission sources and influencing downwind areas, to credit these out of the 

area emission reductions toward the affected area in fulfilling RFP obligations to attaining the 

NAAQS standards. With our previous RFP policy, it was the EPA’s intent to define RFP 

requirements in terms of emissions reductions that can be expected to provide generally regular, 

constant improvement in air quality in the nonattainment area. However, the EPA’s preferred 

policy to allow ROP credit for “outside” reductions was refuted by the D.C. Court in the NRDC

case, therefore, the agency believes we cannot lawfully allow credits for emissions reductions 

occurring outside of a nonattainment area to apply to ROP/RFP requirements in the area. 

Therefore, the final rule will require ROP/RFP reductions to be achieved from “baseline 

emissions,” defined as emissions “in the area.”

D. How do RACT and RACM requirements apply for 2008 ozone NAAQS nonattainment 
95

areas?

1. RACT SIP

Comment: RACT “Fix Up”: Marginal area pre-1990 RACT rules

Commenter (0132) stated, the EPA should make clear any requirements regarding RACT for 

Marginal nonattainment areas under the 2008 8-hour ozone NAAQS. The Commenter requested 

that, the EPA clarify that if a state has already made corrections to any applicable pre-1990 

RACT rules that have been approved by the EPA as a SIP revision, then the state has already 

satisfied its obligation under §182(a)(2)(A) for a Marginal nonattainment area for purposes of the 

2008 ozone NAAQS. Commenter (0132) stated that, if the EPA is considering a different 

interpretation for Marginal nonattainment areas under §182(a)(2)(A) for the 2008 8-hour ozone 

NAAQS, then the EPA should propose a supplemental notice of rulemaking and an additional 

comment period so that states have adequate opportunity to review and comment.

Commenter (0180) stated, the rule must require states to submit, within 6 months of designation, 

the RACT provisions required for Marginal areas under 42 U.S.C. § 7511a(a)(2)(A). Commenter 

(0180) stated that, neither the preamble nor the regulatory text in the proposal expressly directs 

Marginal areas for the 2008 standard to submit SIP revisions to meet pre-1990 RACT 

requirements. 78 FR at 34191; See also 42 U.S.C. § 7511a(a)(2)(A). Because the EPA has 

(correctly) determined that implementation of the 2008 standard is governed by subpart 2, 

Commenter (0180) stated, the EPA must require states to comply with all subpart 2 

requirements, including the RACT mandate for Marginal areas. 

Response: The EPA clarifies that the obligations under §182(a)(2)(A) section apply only to 

nonattainment areas designated before 1990. The 2008 ozone NAAQS implementation rule takes 

the same position as the 1997 ozone implementation rule for the application of the RACT “fixup” obligations under §182(a)(2)(A). The 1997 ozone implementation rule took the position that 

§182(a)(2)(A) only applies to pre-1990 nonattainment areas. The RACT fix-up provision under 

§182(a)(2)(A) for a nonattainment area classified as Marginal under the 2008 ozone NAAQS 

would only apply to those areas for which the EPA issued a RACT SIP Call before the 1990 

CAA Amendments. 

Comment: Another round of RACT revisions is neither required by law nor necessary

Commenter (0151) stated that, the EPA’s final rule should not require major sources to adopt 

another round of new or incremental RACT or RACM. Commenter (0151) is claiming that, 

Congress should have considered that the short period of time between ozone NAAQS revisions 

would not allow a facility to recoup the investment in the original pollution control before 

requirement to reconsider if the next round of newer controls is required. The Commenter also 

contents that, it would be enormously burdensome for states to adopt new RACT SIPs and 

resubmit them for EPA approval. For the 2008 ozone NAAQS revisions, the Commenter claims 

another round economy-wide technology evaluation would not reveal significant additional 

technology-based reductions. The Commenter suggested in lieu of another round of RACT 

analysis, the overall ability of a state to adopt a more tactical approach to RACT and SIP-
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planning, such as the proposed ozone reduction targets discussed in the Notice for RFP. The 

Commenter noted that such flexibility should provide states with the ability to determine that 

“incremental RACT or RACM” adjustment is not “reasonable” if additional control is 

minimally-effective at reducing emissions because of the size of a particular facility (or sources 

within the emitting facility), the number and/or types of “other” sources in the nonattainment 

area, or the relative reactivity of the VOC/NOx species that are emitted by local sources and 

should not require a comprehensive demonstration or showing for each type of industrial source 

in the 2008 ozone emission inventory. Importantly, requiring “additional controls for the sake of 

controls” runs counter to the EPA’s recognition elsewhere in the Notice that NOx and/or the 

control of reactive VOC species are a more effective and therefore “reasonable” strategy for 

attaining the ozone standard. Thus, the EPA’s final rule should not require major sources to 

adopt new or incremental RACT or RACM, particularly if it would not be particularly effective 

at reducing ozone in the nonattainment areas. (0151)

Response: The EPA disagrees. First, the CAA includes a requirement that an attainment plan 

must provide for the implementation of all RACM as expeditiously as practicable, including such 

reductions that may be obtained through RACT. Second, the EPA believes the RACT SIP 

provides cost-effective emission reductions that are necessary to attain the NAAQS as 

expeditiously as practicable. Furthermore, as pointed out by a Commenter (0168), an initial 

round of RACT emission reductions in areas upwind of NAAs can be important to attainment of 

the NAAQS in the downwind area, regardless of whether the downwind area has gone through 

prior rounds of RACT SIPs.

The EPA recommends that states refer to the BACT/LAER Clearinghouse and the EPA’s Menu 

of Control Measures as resources for recent technical information. States must provide adequate 

documentation that they have considered control technology that is economically and 

technologically feasible, including consideration of information submitted during the state’s 

public comment period.

Excluding a round of RACT determinations differs considerably from excluding a portion of the 

RFP requirements; i.e., the 15 percent VOC emissions reduction requirement. While the EPA 

believes it is appropriate in some cases to not require a 15 percent VOC emissions reduction a 

second time, additional RFP provisions continue to apply and help provide for attainment as 

expeditiously as practicable. That is, if a state has already met the 15 percent VOC emission 

reduction requirement for the 1-hour standard for an area, then it should not be required to meet 

that requirement a second time for the 8-hour standard but instead will be subject to the other 

applicable RFP provisions of the CAA (70 FR 71635). This provision is a logical means of 

achieving the purposes of the RFP requirement which is to ensure steady progress towards 

attainment and it was upheld in NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009). The EPA’s 

proposal to allow states to consider whether additional RACT is required for VOC sources 

based, for example, on the incremental reactivity of VOC species, similarly does not waive the 

overall RACT requirement, since RACT would apply to all major NOx sources even if some 

VOC sources were not required to conduct a RACT analysis.

The EPA disagrees with the Commenter that Congress did not realize the implications of setting 
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the 5-year NAAQS review cycle would result in the requirement for RACT revisions with each 

NAAQS review to be implemented. While there is no explicit requirement in the CAA for states 

or EPA to periodically review and revise technical assistance for meeting RACT requirements, 

the CAA clearly includes a requirement that an attainment plan must provide for the 

implementation of RACT. The EPA believes the RACT SIP requirement conforms closely to the 

clearly articulated goal of the CAA that states implement measures that provide for attainment of 

the ozone standard as expeditiously as practicable.

Comment: Support RACT emission reductions 

Commenter (0168) stated that, experience has shown that properly implemented RACT achieves 

significant cost effective emission reductions and sets an effective baseline level of emission 

control, and that, experience also shows that for many source sectors the most bang-for-the-buck 

is achieved in the first round of RACT. Commenter (0168) noted that, while they agree that the 

periodic update of a RACT SIP is beneficial, and that, the periodic review and update of RACT 

is good air quality policy, Delaware notes that 1) little reduction in emissions in their state is 

anticipated, 2) this review will take substantial time and resources to complete and most 

importantly, 3) the first round of RACT has yet to be implemented in many of the upwind areas 

that are the primary cause of the state's ozone air quality problems. 

Response: The EPA agrees that the initial round of RACT implementation can be especially 

effective in achieving emission reductions, however the periodic update of a RACT SIP can also 

be beneficial. The EPA acknowledges that as a state with previous nonattainment areas and part 

of an ozone transport region, Delaware has been subject to RACT requirements under the 1979 

and 1997 ozone NAAQS and that many Delaware sources currently may have beyond-RACT 

controls, in which case it is possible that little reduction in Delaware emissions may be expected 

due to another round of RACT reviews. The EPA also agrees that implementation of emissions 

controls, including RACT (where required), in areas upwind of NAAs can be important to the 

ability of the downwind NAA to attain the NAAQS.

2. CTGs and ACTs

Comment: Update CTGs and ACTs and other RACT Guidance

Commenters (0144, 0146, 0155, 0157, 0163, 0167, 0177 and 0180) encouraged the EPA to 

update the CTG and ACT documents. 

Commenter (0155) recommended that, with respect to RACM and RACT, the EPA provide all 

legally available flexibility for reaching attainment. 

Commenters (0144, 0146, 0163, 0167, and 0177) stated, the CTG and ACT guidelines need to be 

updated in order to set a nationwide baseline for presumptive norms and provide consistency in 

states' RACT determinations for CTG and ACT source categories. 

Commenter (0144) stated that, although the proposal (page 34192) indicates states should use 
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current EPA guidance including CTGs and ACTs in making RACT determinations, many of the 

CTGs and ACTs are outdated and no longer represent RACT due to technological advances. 

Commenter (0146) stated, the EPA’s NOx RACT guidance and many of its CTGs are nearly 20 

years old and to allow states, especially those with new nonattainment areas, to develop SIPs and 

rules based on outdated assumptions about available control technologies would undermine 

progress and public health protection.

Commenter (0167) stated that, the potential inequities using outdated RACT guidance may 

compel some states to expend limited resources reviewing and commenting on other states 

proposed SIPs. Commenter (0167) stated, such national guidance may provide air quality 

agencies with leverage needed to complete rule adoption where state law or stakeholder 

resistance may otherwise present obstacles to unilateral state action. 

Commenter (0167) stated, the EPA must as part of RACT, or as a separate action, require 

sources that have installed pollution control equipment continue to operate such equipment. 

Commenter (0177) stated, this piecemeal approach will likely result in drastically different 

interpretations of appropriate RACT levels across the country and compel states to expend 

considerable resources on RACT determinations. (0177)

Commenter (0153) recommended that, the EPA use its authority under section 183(b) and revise 

all existing CTGs (or otherwise make a blanket policy change) so that they do not cover VOC 

sources in a NOx- limited area as long as the area makes NOx reductions toward attainment.

Commenter (0163) supported updating the EPA's outdated RACT guidance including its April 

16, 1992 RACM Policy. 

Commenter (0180) stated, the EPA needs to update its NOx RACT guidance because the 

proposal says states should consider more recent information although the EPA does not propose 

to update any of its existing RACT guidance documents, many of which are badly outdated. 

Commenter (0180) believed, the EPA’s failure to update those documents is unlawful and 

arbitrary, as is its directive to states to use such outdated guidance documents. See 42 U.S.C. 

§7511b(c). Commenter (0180) added that, the RACT requirement is not met by allowing sources 

to rely on guidance as to the lowest emission limitation that the source was capable of meeting 

decades ago with control technology that was (purportedly) reasonably available back then. 

Given the substantial contribution to ozone nonattainment from NOx emissions from utility 

boilers (see, e.g., 76 FR 48208 (Aug. 8, 2011)), Commenter (0180) was particularly concerned 

about continued reliance on the EPA’s grossly outdated 1992 and 1994 RACT guidance for 

utility boilers. See 57 FR 55620, 55625 (Nov. 25, 1992); Memorandum from D. Kent Berry, 

Acting Director, Air Quality Mgmt. Div., EPA, to Regional Air Directors, “Cost-Effective NOx

RACT” (Mar. 16, 1994). 

Further, regarding the basic requirements for RACT SIP submittals (78 FR at 34192/3), 

Commenter (0180) stated, the EPA needs to clarify that: a) states must (not merely “should”) 

provide adequate documentation that they have considered all control technologies, including 
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post-combustion controls and fuel switching, that are economically and technologically feasible, 

and must further show that the technology chosen as RACT provides the lowest emission 

limitation; b) the analysis of economic and technological feasibility must be based on 

information that is current as of the time of development of the RACT SIP for the 2008 ozone 

NAAQS, and it is not sufficient for states to rely on previous RACT determinations without 

considering more recent information; c) states must consider controls that public comment 

identifies as meeting the definition of RACT and must provide a reasoned justification for 

rejecting such controls in favor of less stringent controls; and d) controls that have been achieved 

in practice by other existing sources in the same source category must ordinarily be considered 

technologically and economically feasible.

Commenter (0180) stated that, NOx RACT should be based on an emission limit no less stringent 

than 0.070 lb/MMBtu. Commenter (0180) asserted that taking even the highest emission rate 

that, the EPA has set with no post-combustion control, 0.5 lb/MMBtu and applying the 90 

percent control from SCR, an emission limit of 0.05 lb/MMBtu should be RACT. Commenter 

(0180) suggested, the EPA could add a 40 percent “safety factor” and recommend that NOx

RACT be set at 0.070 lb/MMBtu. Commenter (0180) asserted that, a review of the 

RACT/BACT/LAER clearinghouse demonstrates that numerous PSD permits for coal-burning 

boilers were issued during the “coal rush” of the first decade of this century with emission limits 

of 0.07 lb/MMBtu and that actual data confirms that 0.070 lb/MMBtu is easily achievable. (See 

Exhibit B to these comments.)

Commenter (0180) stated that, the NOx RACT limit should be based on an averaging time of no 

longer than 24 hours, ideally, based on a 1-hour or 8-hour averaging time to protect the 8-hour 

averaging time of the 2008 ozone NAAQS. Commenter (0180) asserted, this is especially 

important for coal burning EGUs because electricity demand tends to be highest on hot, summer 

days and these are also times when ozone is the worst. Thus, Commenter (0180) concluded that, 

without short-term averaging times, EGUs will emit NOx at higher levels at precisely the times 

when the ozone problem is the worst and then comply with a longer-term average emission limit 

by lowering their NOx emissions at times when the ozone problem is not as severe. 

Response: The agency developed many of the CTGs and ACT documents over a period from the 

late 1970s to mid-1990s. The CTG’s recommend “presumptive norms” of control for each source 

category, but individual sources may have alternative RACT requirements imposed by making 

an adequate infeasibility demonstration (44 FR 53761, September 17, 1979). The CTGs address 

entire source categories and entire industry processes and describe what requirements the EPA 

generally will approve as RACT. 

The EPA recommends the BACT/LAER Clearinghouse and the EPA’s Menu of Control 

Measures as resources for recent technical information, but does not require consultation by each 

state with these resources. Rather, states need to provide adequate documentation that they have 

considered control technology that is economically and technologically feasible, including 

consideration of information submitted during the state’s public comment period. States should 

refer to the existing CTGs and ACTs for purposes of meeting their RACT requirements, as well 

as all relevant information (including recent technical information as well as information 
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received during the public comment period) that is available at the time that they are developing 

their RACT SIPs for the 2008 ozone NAAQS. We believe that there is sufficient information 

available to states to inform their RACT determinations.

The EPA disagrees that failure to update the CTG documents is unlawful and arbitrary. Under 

CAA section 183(c), CTGs and ACTs are to be revised and updated “as the Administrator 

determines necessary.” Additionally, we disagree with the statement that the EPA issued a 

“directive” to states to use outdated guidance documents. Rather, the issued guidance through the 

preamble to the proposed rule, stating the following: “States should use current EPA guidance 

and any other information available in making RACT determinations. The EPA recognizes that 

existing CTGs and ACTs for many source categories have not been revised in a number of years. 

However, in many cases, more recent technical information is available in other forms, such as 

the BACT/LAER Clearinghouse.” (78 FR 34192). We agree with the Commenter that, in some 

cases, it may not be appropriate for states to rely solely on a CTG document for purposes of 

meeting their RACT requirements, which is why we encouraged states in the preamble to the 

proposed rule to consider additional information that may be available. 

The EPA appreciates the Commenter’s thoughtfulness regarding recommended costeffectiveness and emission limits as well as averaging times for certain sources. We will take this 

input into consideration if we are updating any CTG documents in the future. 

Comment: CTG for oil and gas equipment

Commenter (0170) requested that, the EPA issue CTGs for oil and gas equipment to assist states 

in meeting the 2008 ozone NAAQS as part of the Ozone Implementation Rule. (Commenter 

incorporated by reference the document filed with the “In re Petition for the U.S. Environmental 

Protection Agency to 1) Promptly Require Oil and Gas Owners and Operators to Monitor for 

Ozone and 2) To Issue CTGs for Oil and Natural Gas Operations in Non-Attainment Areas” 

(December 19, 2012), EPA Doc. No. EPA-HQ-OAR-2010-0505-4608.) Commenter believes 

that, CTGs provide a valuable framework allowing the EPA to issue guidance on cost-effective 

emission reduction technologies for the oil and gas sector and provide important air quality 

planning tools for communities that are seeking to reduce emissions and achieve compliance 

with the NAAQS along with those attainment areas that are pursuing reductions under the EPA’s 

Ozone Advance Program.

Response: The EPA is evaluating issues raised in the petition submitted to the EPA that is noted 

in the comment (Doc. No. EPA-HQ-OAR-2010-0505-4608).

Comment: RACT implementation timing

Commenter (0152) was concerned that, the EPA’s proposed requirement to have RACT in place 

by January 1, 2017, may not provide enough time for implementation. Commenter (0152) 

believed, RACT requirements require regulation development with prior notice of 

implementation deadlines and that if the EPA needs to further develop additional CTGs for the 

current ozone standards, states may not have ample time to develop regulations that provide 

sufficient time for sources to implement RACT.
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Response: The EPA disagrees with the Commenter that, a requirement for RACT to be in place 

by January 1, 2017, for areas designated nonattainment effective July 20, 2012, (and all areas of 

the OTR) does not allow enough time for implementation. The EPA believes that the January 1, 

2017, date would allow a sufficient amount of time for states to make determinations and for 

sources to meet RACT requirements on the time-table originally anticipated under the 1990 

CAA Amendments, consistent with the Moderate area attainment date of July 20, 2018. 

The EPA appreciates the Commenter’s concerns regarding the need for sufficient time for 

sources to meet RACT requirements. On consideration of the comment, the EPA believes that 

the proposal language may not have been clear with regard to RACT implementation deadlines. 

Thus, we provide more clarity in the paragraphs that follow.

First, the EPA notes that the requirement to develop a RACT SIP applies only to areas that are 

designated as Moderate or above (i.e., Serious, Severe, or Extreme). For such areas that were 

designated on July 20, 2012, RACT SIPs are due within 2 years of the effective date of 

designation, by July 20, 2014. Sources subject to RACT in those areas would then need to 

implement RACT by January 1, 2017.16 If an area is reclassified from Marginal to Moderate at 

some later date, then at that time that area would become subject to the RACT requirement, and 

the EPA would set new SIP submission and RACT compliance dates on a schedule that the EPA 

will establish in the applicable notice and comment rulemaking reclassifying the area. For areas 

that are newly redesignated to nonattainment, the RACT SIP is due no later than 2 years from the 

effective date of designation and the implementation deadline is no later than January 1st of the 

5th year after the effective date of redesignation. 

Second, we wish to clarify that the January 1, 2017, RACT implementation deadline would not 

automatically apply to sources covered by future CTGs. If a new CTG is developed, all current 

Moderate or above areas would be required to revise their SIPs for the sources covered by the 

CTG within the period set forth by the EPA in issuing the CTG document (See section 182(b)(2) 

of the CAA), which would occur through notice and comment rulemaking. This will give sources 

lead time to comply with the new requirement. 

3. RACT determinations

Comment: Supplement use of old CTGs and ACTs

Commenter (0168) agreed with the proposal that, technological feasibility should be based on 

information that is current as of the time of development of the RACT SIP for the 2008 ozone 

 

16

 We note that the RACT compliance date does not change relative to the RACT SIP 

submission. This compliance date is fixed, such that if a state submits a RACT SIP past the July 

20, 2014 deadline, then sources would still have to comply with the RACT requirements by 

January 1, 2017.
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NAAQS - that it is not sufficient for states to rely on previous RACT determinations without 

considering more recent information.

Commenter (0172) supported flexibility in implementing the RACT requirements noting that, the 

EPA stated in the proposal that many CTGs and ACTs are nearly two decades old and more 

recent information such as BACT determinations should be taken into consideration for RACT.

Response: The EPA agrees with the Commenters.

Comment: Certification of existing RACT

Commenter (0153) stated that, the EPA should provide a clear indication of situations where a 

state may conclude that existing RACT meets RACT for the 2008 ozone NAAQS since, without 

such clarification, regional offices may find it difficult to approve a state submittal that contains 

such a conclusion.

Commenters (0144 and 0146) stated that, although in some cases a recent RACT analysis may 

result in such a certification, in no instance should 1-hour ozone (120 ppb) RACT be considered 

RACT for the 2008 8-hour ozone (75 ppb). Commenter (0144) stated that, such certifications of 

20-year old RACT determinations put states that have implemented more stringent RACT 

measures at a disadvantage for attainment. Commenter (0144) supported the statement in the 

proposal (page 34192) "it is not sufficient for states to rely on previous RACT determinations 

without considering more recent information." Commenter (0146) stated that, RACT 

certifications for the 2008 ozone NAAQS must be based on a full RACT analysis, as required 

under the CAA, and under no circumstances should RACT for the previous 1-hour standard be 

considered RACT under the 2008 NAAQS.

Commenter (0159) supported the finding by the EPA that, in some cases, states may conclude 

that sources already subject to RACT for the 1-hour and/or 1997 ozone NAAQS are also meeting 

the 2008 ozone NAAQS RACT requirement. 

Response: In the preamble to the proposed rule, the EPA noted that in some cases, states may 

conclude that sources already addressed by RACT determinations for the 1-hour and/or 1997 

ozone NAAQS may not need to implement additional controls to meet the 2008 ozone NAAQS 

RACT requirement. The EPA disagrees with the comments that RACT for the 1-hour ozone 

NAAQS should not be considered RACT for the 2008 8-hr ozone NAAQS. In areas subject to 

the major source RACT requirement under the 1-hour and/or 1997 ozone NAAQS, states may in 

some cases, after careful assessment, conclude that a new RACT determination under the 2008 

standard would result in the same or similar control technology as the initial RACT 

determination under the 1-hour or 1997 standard because the fundamental control techniques, as 

described in the CTGs and ACTs, are still applicable.

The EPA acknowledges the request for further information about circumstances that may lead a 

state to conclude that existing RACT controls meet the RACT requirement for the 2008 ozone 

NAAQS. We provide further clarity regarding this issue in the paragraphs that follow. However, 

the EPA disagrees with the Commenter that, the EPA Regional Offices may find it difficult to 
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approve a state conclusion that existing RACT meets RACT for the 2008 ozone NAAQS. Given 

the unique circumstances for each nonattainment area, the EPA intends to review each RACT 

SIP on a case-by-case basis. We strongly encourage states to work with their Regional Offices in 

determining RACT for purposes of meeting the RACT requirements for the 2008 NAAQS.

In cases where controls were applied due to the 1-hour or 1997 ozone NAAQS RACT 

requirement, we expect that any incremental emissions reductions from application of updated 

RACT controls may be small and, therefore, the cost for advancing that small additional 

increment of reduction may not be reasonable. In contrast, a RACT analysis for uncontrolled or 

partially controlled sources would be much more likely to find that updated RACT-level controls 

under the 2008 ozone NAAQS are economically and technically feasible. 

The CTGs and ACTs for VOC were completed over a period from the late 1970s to mid-1990s. 

The EPA also issued additional CTGs in 2006, 2007 and 2008. In some cases these CTGs 

updated previously issued CTGs and in other cases, they covered new categories of sources. The 

CTGs are still used to presumptively define VOC RACT.

The EPA issued NOx ACT documents between 1992 and 1995. In September 2000, updates to 

the NOx ACT documents were completed for stationary internal combustion engines and cement

kilns. The NOx and VOC ACTs describe available control techniques and their cost 

effectiveness, but do not define presumptive RACT levels as the CTGs do. Updating the ACTs 

would not, by itself, change the EPA’s NOx or VOC RACT guidance, but it could provide 

information that would lead to a new conclusion as to which control measures constitute RACT 

for a specific source or source category. Progress has been made in improving the cost 

effectiveness of some NOx and VOC controls. 

We recognize that many of the CTGs/ACTs have not been revised in quite some time and thus 

may not provide the most accurate picture of current control options. Therefore, we advise states 

to consider new information that has become available before certifying that a prior 1-hour ozone 

RACT determination or a 1997 ozone RACT determination, even where controls were required, 

still represents an appropriate RACT level of control for the 2008 ozone program. In the 

alternative, the state should revise the SIP to reflect a modified RACT requirement for specific 

sources or source categories. In cases where additional information is presented, for example, as 

part of notice-and-comment rulemaking on a RACT SIP submittal, states (and the EPA) would 

necessarily consider the additional data in reviewing what control obligation is consistent with 

RACT. 

In portions of 2008 ozone nonattainment areas where control technologies for major sources or 

source categories were previously reviewed and controls applied to meet the RACT requirement 

under the 1-hour or the 1997 standard, states should review and, if appropriate, may accept the 

initial RACT analysis as meeting the RACT requirements for the 2008 standard. Absent new

data or public comments indicating that the previous RACT determination is no longer 

appropriate, the state may conclude that additional SIP controls are not necessary to meet the 

RACT requirement for these sources for the 2008 standard. In such cases, the state’s SIP revision 

submitted after notice and comment should contain a certification, with appropriate supporting 
104

information, (including consideration of new data), indicating that these sources are already 

subject to SIP-approved requirements that still meet the RACT obligation. There are cases where 

the initial RACT analysis under the 1-hour standard or the 1997 standard for a specific source or 

source category concluded that no additional controls were necessary. In such cases, a new 

RACT determination is needed to consider whether more cost effective control measures have 

become available for sources that were not previously regulated. A re-analysis may determine 

that controls are now economically and technically feasible and are necessary to meet the RACT 

requirements. 

Comment: Alternate control technology for RACT

Commenter (0129) encouraged the EPA to provide the states the flexibility to consider alternate 

control technology when developing their RACT SIP, provided adequate justification for the 

technical and economic feasibility of such approaches is also provided. 

Response: When developing their RACT SIPs, states must consider control technology that is 

economically and technologically feasible and is based on the most recent information available. 

In the preamble to the proposed rule, the EPA acknowledged that some CTGs and ACTs are 

outdated and provided examples of more recent technical information sources that states may 

refer to when developing their RACT SIPs. We would also encourage states to work closely with 

their respective Regional Offices should they need assistance locating additional information 

sources that may be helpful in developing their RACT SIPs.

Comment: Controls that have been achieved in practice

Commenters (0144 and 0180) supported the statement in the proposal where the EPA "generally 

considers controls that have been achieved in practice by other existing sources in the same 

source category to be technologically and economically feasible." 

Response: The EPA agrees with the Commenters.

4. Averaging over a nonattainment area

Comment: Commenter (0144) did not support a nonattainment area-wide weighted NOx

averaging demonstration that exempts HEDD EGUs from NOx control. The Commenter stated 

that, an exemption of HEDD EGUs from NOx control does not reduce NOx emissions when and 

where such reductions are necessary to attain the ozone NAAQS. 

Commenter (0180) stated that, the EPA’s definition of RACT plainly requires each individual 

source to apply control technology to achieve the lowest emission limitation that each particular 

source is capable of meeting considering technology and economic feasibility. Commenter 

(0180) stated that, substitution of area-wide averaging for source-specific RACT also flouts the 

language of section 182(b)(2) of the Act, which requires SIPs for Moderate and above areas to 

require implementation of RACT “with respect to ... [a]ll VOC sources in the area covered by 

any CTG issued before November 15, 1990,” and “[a]ll other major stationary sources of VOC 
105

that are located in the area.” 42 U.S.C. § 7511a(b)(2). Commenter (0180) stated, the EPA cannot 

supplant these statutory directives with an area-wide averaging program that allows some 

sources to avoid installing RACT controls at all. 

Response: The EPA’s existing policy recognizes that states can meet NOx RACT requirements 

by submitting as part of their NOx RACT SIP submittal a demonstration that the weighted 

average NOx emission rate from sources in the nonattainment area subject to RACT achieves 

RACT-level reductions. We note, however, that this policy does not include an exemption for 

HEDD EGUs from NOx control. 

The EPA disagrees with the comment that “area-wide averaging is not a legally permissible 

method for complying with” RACT and that RACT requires reductions from “each and every 

source” in an area. The EPA believes that the statute, as interpreted by the court in NRDC v. 

EPA, allows each state the option of demonstrating that its program achieves RACT level 

reductions by showing emission reductions greater than or equal to reductions that would be 

achieved through a source-specific application of RACT in the nonattainment area. NRDC v. 

EPA interprets the CAA as requiring that each nonattainment area must achieve “RACT-level 

reductions,” which is to say the reductions that would be achieved “if RACT-level controls were 

installed in the area.” 571 F.3d at 1258. In sum, nothing in the CAA or in NRDC v. EPA requires 

that “each and every” source in the area employ RACT or individually achieve RACT-level 

reductions. 

The Commenter attaches too much significance to the EPA’s reference to RACT as the lowest 

emission limitation that “a particular source” is capable of meeting. 78 FR 34191 n. 33. The 

Commenter suggests that this requires that each particular source meet the limitation, but EPA 

does not agree with this. The quoted language does no more than reflect the fact that sourcespecific control assumptions would need to be developed in order to determine the overall 

reduction level that would be achievable in a nonattainment area through source-specific 

application of RACT. Moreover, as noted in the proposal, the EPA believes states are in a better 

position than EPA to conduct this analysis (78 FR 34193). Consistent with previous guidance, 

the EPA continues to believe that RACT can be met on average by a group of sources within a

nonattainment area rather than at each individual source. Therefore, states can show that SIP 

provisions for these sources meet the ozone RACT requirement using the area-wide averaging

approach.

5. Trading within a nonattainment area

Comment: Commenters (0132 and 0163) supported allowing states to rely on participation in a 

nonattainment area cap and trade program to satisfy RACT requirements.

Commenter (0132) believed that for sources located within a nonattainment area, cap and trade 

programs that are limited to that nonattainment area can provide additional flexibility to affected 

sources while still achieving significant emission reductions that satisfy RACT. 

Commenter (0163) believed that it is possible to design and implement a trading program for 
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RACT that achieves enforceable, contemporaneous emissions limitations equal to RACT. Such a 

program could allow multiple sources within a nonattainment area to enter into an enforceable 

permit to comply with an overall weighted average RACT emission limit based on their 

operation over a single day. This assures that RACT is met in the area each day.

Response: Unless there are federal or state regulations, or permit(s) issued to a source containing 

a condition or conditions precluding such use, the EPA agrees with the Commenter that, states 

may rely on a cap-and-trade program that is limited to a nonattainment area for purposes of 

meeting RACT for sources located in the nonattainment area. In order to rely on such a cap and 

trade program for purposes of meeting the RACT requirements, the state should demonstrate that 

the program achieves reductions greater than, or equal to RACT and that, the program ensures 

that all necessary reductions will occur within the nonattainment area. For example; See 30 

Texas Administrative Code, Chapter 117, sections 9800(a)(1) and (2). 

6. Regional trading program

Comment: Support the option that a regional trading program may meet RACT

Commenters (0158, 0159, 0163 and 0166) supported the proposed option that would allow states 

to demonstrate that compliance with a regional trading program, such as CAIR, by affected 

sources within a nonattainment area will satisfy RACT requirements for those sources. 

Commenter (0159) supported this approach, as it focuses on sources within the non-attainment 

area that produce locally beneficial emissions reductions. Commenter (0166) encouraged the 

EPA to approve SIPs that make a showing to that effect and stated that the EPA also should 

assist states in making these determinations by providing tools and data that will allow states to 

do so.

Response: The EPA thanks the Commenters for their thoughtful comments in support of the 

proposed approach, which would allow states to demonstrate that compliance with a regional 

trading program by sources within the nonattainment areas are satisfying RACT requirements for 

the nonattainment area. A SIP that includes such an analysis will be reviewed by the EPA on a 

case-by-case basis to evaluate the extent to which the analysis demonstrates that source 

participation in the trading program in fact achieves emission reductions within the 

nonattainment area that are equal to, or greater than, application of RACT in that nonattainment 

area. The EPA encourages states to work with their respective EPA Regional Offices to seek 

guidance when conducting their local area analyses.

Comment: Do not support the option that a regional trading program may meet RACT

Commenters (0144, 0146, 0163, 0168, 0180 and 0177) did not support the proposal that states 

have the option of demonstrating that compliance with a regional trading program by certain 

sources within a nonattainment area will achieve RACT level reductions for those sources within 

that nonattainment area.

Commenter (0144) stated that it does not support ozone season trading of NOx emissions. A 

trading program that allows higher NOx emissions on high ozone days makes it difficult for 
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states that are subjected to upwind sources of NOx to achieve the ozone standard. 

Commenter (0146) stated that neither states nor the EPA can guarantee such reductions either 

locationally or temporally through a regional cap-and-trade program; instead, the EPA needs to 

thoroughly review source-specific RACT certifications and require the operation of all 

implemented RACT controls. 

Commenter (0163) disagreed with this approach because a regional trading program such as 

CAIR does not include requirements for enforceable, contemporaneous reductions required by 

CAA section 172 (c)(6). Commenter (0163) stated that while RACT requires source-by-source 

application of controls with a daily or 30-day rolling average, CAIR is a multi-state, seasonal and 

annual program and, with the banking and trading provisions of CAIR, there is no certainty that 

emissions would remain below RACT levels from one year to the next. The commenter further 

stated that it is possible to design and implement a trading program for RACT that achieves 

enforceable, contemporaneous emissions limitations equal to RACT. New York has instituted 

such a program, which allows multiple sources within the New York City nonattainment area to 

enter into an enforceable permit to comply with an overall weighted average emission limit 

based on their operation over a single day. This assures that RACT is met in the area each day.

Commenter (0168) stated that the EPA's past reliance on trading programs to fulfill substantive 

requirements like RACT and best available retrofit technology (BART) have resulted in many 

significant sources remaining uncontrolled in upwind areas, which significantly and negatively 

impact air quality in some downwind areas. The Commenter recommended that RACT apply to 

every stationary source on a unit-by-unit basis.

Commenters (0144 and 0177) stated that the EPA should ensure that NOx sources with 

previously installed air pollution control equipment are required to fully operate those controls 

during the ozone season. The Commenters pointed out that some sources that are upwind 

contributors to downwind nonattainment areas turn off their NOx controls and simply buy NOx

allowances to meet their emissions requirements. This adversely impacts air quality in downwind 

areas.

Commenter (0180) cited NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009) for the proposition that

the Clean Air Act does not allow states to rely on the participation of a source in a regional 

trading program to satisfy RACT requirements. 

The Commenter stated that the EPA needs to clarify that such a demonstration is not sufficiently 

made merely because a source has installed controls to comply with a regional trading program, 

or is predicted to reduce its emissions to an assumed level since a source can install emission 

controls and then simply choose not to operate such controls on a given day or during a given 

time period as long as it has enough allowances under the regional trading program to cover its 

emissions. Commenter (0180) stated that, under CAIR, a source with RACT-level controls could 

shut down entirely and sell its allowances to other sources in the nonattainment area that do not 

have RACT-level controls. Commenter (0180) stated, the Act mandates that SIPs “require” 

implementation of RACT but that a “prediction” that sources are likely to choose to limit their 
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emissions to RACT levels within a nonattainment area under a trading program that does not 

require them to do so – and that in fact allows them to avoid implementing RACT controls –

does not satisfy these statutory requirements.

Response: The EPA agrees that mere participation in a regional trading program, such as CAIR, 

by sources in a particular nonattainment area is not sufficient for purposes of demonstrating that 

those sources have met their RACT requirements for the nonattainment area. As explained in the 

preamble to the proposed rule, the statute provides that RACT SIPs must demonstrate that 

RACT-level emission reductions are achieved within the relevant nonattainment area. Thus, it 

does not allow states to rely upon the participation of a source in a regional cap-and-trade 

program to satisfy RACT requirements without a demonstration that that participation results in 

emission reductions equivalent to those achieved through the installation of RACT controls.

Additionally, the EPA agrees that states may not merely claim that a source has met RACT by 

installing controls as part of a regional trading program. States must, as part of their RACT SIP 

submission, demonstrate that the controls put in place at a source are in fact RACT. 

The EPA disagrees with those commenters that say that states should not have the option to 

demonstrate that compliance with a regional trading program by sources in a nonattainment area 

achieves RACT-level reductions within the nonattainment area. In NRDC v. EPA, the case cited 

by Commenters, the D.C. Circuit noted that a determination that RACT was satisfied by 

compliance with a regional trading program might be permissible for an area if accompanied by 

a technical analysis demonstrating that the program in fact “results in greater emissions 

reductions in a nonattainment area than would be achieved if RACT-level controls were installed 

in that area.”17 In other words, the Court rejected the notion that a regional trading program 

intended to eliminate interstate transport of emissions consistent with section 110(a)(2)(D)(i)(I)

could automatically constitute the RACT-level of control required by section 172(c)(1), but held 

open the possibility that an analysis could be conducted to determine whether such a program 

would result in the same or higher level of emissions reductions in individual nonattainment 

areas. We note that this is an option available to states, not a requirement, and if a state so 

chooses, it may establish RACT requirements on a unit-by-unit basis and not provide for area 

wide averaging. In such cases, a review of the past level of control achieved by units with SCR, 

SNCR, or any other type of NOx control would be relevant to the review of RACT under the 

2008 ozone NAAQS.

The EPA disagrees, however, with any comments that RACT requires a source-by-source 

application of controls and any implication by the commenters that, the proposal should address 

whether controls are required to be operational at all times at sources in the nonattainment area. 

RACT can be met on average by a group of sources within a nonattainment area rather than at 

each individual source. Nothing in the CAA or in NRDC v. EPA requires that each and every 

source in the area employ RACT or individually achieve RACT-level reductions. Further, the 

 

17 571 F.3d 1245,1258 (D.C. Cir. 2009).
109

EPA’s NOx RACT guidance (NOx Supplement to the General Preamble, 57 FR 55625,

November 25, 1992) encouraged states to develop RACT programs that are based on “area wide 

average emission rates.” Additional guidance on area-wide RACT provisions is provided by 

EPA’s January 2001 economic incentive program guidance titled, “Improving Air Quality with 

Economic Incentive Programs.” Thus, the EPA’s existing policy recognizes that states may 

demonstrate as part of their NOx RACT SIP submittal that the weighted average NOx emission 

rate from a group of sources in the nonattainment area subject to RACT meets NOx RACT 

requirements. 

Regarding the Commenters’ concerns about enforceability and the timeframe within which 

RACT controls should be applied (i.e., daily or 30-day rolling average), the EPA notes that 

through the final rule, we merely provide the option for states to make a demonstration that 

sources’ participation in a trading program achieves equivalent or greater emission reductions

within the nonattainment area as RACT-level controls would. The preservation of this option 

does not prejudge the substance of what those demonstrations will contain, and the specific 

arguments raised by commenters are more properly addressed in the context of the case-by-case 

determinations of whether the demonstrations meet the RACT requirement. 

Comment: Is CAIR equivalent to RACT?

Commenter (0152) believed CAIR or other regional trading programs should continue to be 

equivalent to RACT for EGUs without the need for analysis beyond what EPA has already 

prepared. If challenged, Commenter (0152) stated, the EPA will be in a position to better explain 

to the courts why this is appropriate compared to prior decisions regarding the NOx SIP Call.

Response: The EPA disagrees with the comment that CAIR or other regional trading programs 

should continue to be automatically treated as equivalent to RACT for EGUs without the need 

for an analysis. In NRDC v. EPA (571 F.3d 1245 (DC Cir. 2009), the Court rejected the notion 

that a regional cap-and-trade program intended to eliminate interstate transport of emissions 

consistent with section 110(a)(2)(D)(i) could automatically constitute RACT-level control as 

required by section 172(c)(1).The Court specifically held that the Phase 2 Ozone Implementation 

Rule allowing use of the NOx SIP call to constitute RACT without any locally applicable 

analysis regarding the equivalence of NOx SIP Call and RACT reductions: “is inconsistent with 

the CAA . . . in allowing participation in a regional cap-and-trade program to satisfy an areaspecific statutory mandate.” The Court emphasized that: “the RACT requirement calls for 

reductions in emissions from sources in the area; reductions from sources outside the 

nonattainment area do not satisfy the requirement . . . Accordingly, participation in the NOx SIP 

call would constitute RACT only if participation entailed at least RACT-level reductions in 

emissions from sources within the nonattainment area.” This reasoning applies equally to any 

trading program that allows trading across nonattainment area boundaries. Therefore, the EPA 

could not, consistent with the NRDC opinion (NRDC v. EPA, 571 F.3d 1245) approve a SIP that 

found compliance with CAIR to satisfy RACT requirements but did not included the necessary 

analysis showing that sufficient reductions in the nonattainment area would be achieved under 

the trading program.
110

Additionally, the EPA disagrees with the Commenter that, there is no need for an analysis 

beyond what the EPA has already prepared. To the extent that the Commenter is referring to the 

Supplemental Technical Analysis that EPA conducted to assess whether compliance with CAIR 

could satisfy the NOx RACT requirement for EGUs in certain geographic areas,18 the EPA no 

longer believes that this analysis provides an adequate demonstration that participation in the 

CAIR is projected to achieve equal or greater annual emissions reductions from EGUs than 

source-by-source RACT for certain specific areas. The EPA has concluded that the analysis’s 

across-the-board assumptions regarding what constitutes RACT for all sources in all 

nonattainment areas were inadequate and did not consider whether more advanced control 

technologies, such as post-combustion controls (e.g., selective catalytic reduction or selective 

non-catalytic reduction), might at some time be technically and economically feasible for 

specific sources in some areas. 

7. Consideration of the limited impact of VOC emissions in some areas

Comment: Support consideration of limited impact of VOC controls in areas that are NOxlimited

Commenters (0129, 0130, 0132, 0136, 0137, 0140, 0151, 0159, 0161, 0162, 0169, 0172, 0178 

and 0179) generally supported an approach that would allow state RACT determinations to take 

into consideration the limited impact of VOC emission reductions on reducing ozone 

concentrations in some areas.

Commenters (0132 and 0179) stated, the EPA has historically interpreted CAA, § 172(c)(1) as a 

requirement that the SIP incorporate all RACM that would advance an area's attainment date (57 

FR 13498) and, since §172(c)(1) and §182(b)(2) include RACT as a subset of the broader 

RACM requirement, the Commenter supported allowing state RACT determinations to take into 

consideration whether the associated VOC emission reductions would advance the area's 

attainment date. 

Commenter (0129) suggested that, this substitution be allowed on a source category basis rather 

than a case-by-case basis to avoid unnecessary financial burdens on state agencies.

Commenter (0130) stated that, imposition of VOC controls in areas that are NOx-limited is 

burdensome to both the regulated entity as well as the state, which must determine, implement, 

and enforce these controls. 

 

18 See “Technical Support Document for Phase 2 of the Final Rule to Implement the 8-Hour 

Ozone National Ambient Air Quality Standard-Notice of Reconsideration; NOx RACT for EGUs 

in CAIR States – Supplemental Technical Analysis,” December 2006.(Docket ID no. EPA-HQOAR-2003-0079, item number EPA-HQ-OAR-2003-0079-1044.2) (Supplemental Technical 

Analysis).
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Commenters (0151, 0153) agreed with the EPA that, NOx reductions also may be quicker to 

implement and can be made at lower cost.

Commenter (0169) stated that, it is burdensome and inappropriate for individual states to be 

asked to define thresholds for "ineffective" and to define a test for concluding that the effect of 

additional VOC reductions would be negligible; rather, the EPA is tasked with these types of 

decisions, not states, to ensure national consistency is met.

Commenters (0129, 0132, 0136, 0152, 0161 and 0169) stated that, this approach would allow 

states the flexibility to tailor RACT requirements to the geographically-specific limitations of 

each nonattainment area. 

Commenter (0129) stated that, given the agency's recognition of the utility of NOx control 

technology for reducing ozone, they strongly encourage the final rule to include an explicit 

requirement that state RACT determinations allow substitution of NOx RACT rules for VOC 

RACT rules in geographic areas where biogenic and mobile source VOC production exceeds the 

VOC contribution from stationary sources. 

Commenter (0153) stated, this flexibility should be limited to cases where it can be scientifically 

demonstrated that additional VOC controls are ineffective in reducing ambient ozone 

concentrations.

Commenter (0161) stated that, states should have the flexibility to implement a SIP tailored to 

the particular circumstances present in nonattainment areas in each state and that the EPA has 

authority under the CAA to implement rules giving states this flexibility, because Congress has 

delegated to the EPA identification and implementation of RACT requirements (See 78 FR 

34191). Commenter (0161) stated that, allowing states to tailor RACT to the specific 

circumstances of the nonattainment area would be a reasonable exercise of agency discretion 

[See Chevron U.S.A. Inc. v. NRDC, 467 U.S. 837, 842-43 (1984)]. 

Commenter (0178) supported state, flexibility in order to avoid the situation in which small 

additional VOC reductions actually yield a disbenefit to the ozone air quality concentration 

through the corresponding NOx increases from RACT-required add-on thermal-oxidizing 

controls. 

Commenter (0130) stated that, these modifications should extend beyond section 182(b)(2) 

RACT requirements to those required for areas within the OTR. 

Commenter (0140) stated, the EPA should allow states to demonstrate that adoption of VOC 

RACT rules would not be “reasonable” if, as a whole, adoption of such rules for a nonattainment 

area would not reduce ozone levels “significantly.” The Commenter argued that, “significantly” 

can be defined as an average contribution of over 0.75 ppb (1 percent of the level of the standard, 

which EPA used for defining a “significant” air quality contribution for the Cross-State Air 

Pollution Rule) or 1 ppb (which would definitely be enough of an impact to make the difference 

between an area attaining or not attaining the standard) for all days when 8-hour ozone is 
112

modelled to exceed 75 ppb. For example, the University of Texas at Austin’s (UT’s) modelling 

of 25 percent and 50 percent reductions in anthropogenic VOC emissions only reduced 8-hour 

ozone levels at Travis County’s key regulatory ozone monitor by an average of 0.17 ppb and 

0.35 ppb, respectively, across all of the days with an ozone violation during the June 2006 ozone 

episode developed by TCEQ. Likewise, APCA modelling on the same episode indicated that 

emissions from the Austin-Round Rock MSA only accounted for 21 percent of the ozone levels 

modelled at the key regulatory monitor in the MSA on high ozone days in the June 2006 episode, 

while other emissions from other areas of the state accounted for 26 percent of the ozone levels 

modelled within the MSA. 

Commenter (0151) stated, the agency should assure states in the final rulemaking that even if 

there is not a more reactive VOC species or a NOx source, the fact that it is relatively ineffective 

to control certain VOC with minimal photochemical ozone potential also should be considered in 

determining if RACT exists for that source. The EPA should address the situation where a state 

determines not to regulate the source of a low reactive VOC but the state still cannot demonstrate

timely attainment of the NAAQS. 

Commenter (0153) stated that; the evaluation of what is economically feasible should consider 

the cost/ton, impact/ton and cost/impact for NOx and VOC. The commenter suggested that a

demonstration should be provided for all point and area VOC sources in the nonattainment area. 

The commenter further suggested that a demonstration should involve running a photochemical 

grid model twice, once with all point and area VOC emissions and again with the point and area 

VOC emissions zeroed out. If the impacts are less than 1 percent of the NAAQS (0.75 ppb), then 

all RACT sources are "ineffective" at reducing ozone concentrations and the effect of additional 

VOC reductions would be "negligible." If VOC reductions are shown to be "ineffective", then 

the impact on public health and welfare would be "negligible." The commenter suggested that 

the EPA should set clear, unambiguous, minimum requirements for approvable scientific 

demonstrations so that state agencies can design, perform, and document their demonstrations 

with a reasonable assurance of the EPA approval. The commenter concluded that definitive 

requirements will also allow the EPA to promptly review and act on state demonstrations. 

Commenter (0179) stated that, if control technology aimed at reducing anthropogenic VOC 

shows some benefit, but is not needed to attain and maintain the ozone standard because other 

measures are shown to be more than enough, then it should not be considered RACT. The 

Commenter requested this flexibility for individual sources as well as source categories. 

Several Commenters (0129, 0130 and 0140) stated that, in some nonattainment areas, additional 

reductions of anthropogenic VOC emissions have been scientifically demonstrated to have a 

limited impact on reducing ozone concentrations and encouraged the EPA to allow such a 

scientific demonstration to be considered when determining whether a control technology is 

reasonable in a RACT analysis. 

Commenter (0151) stated that, it would be unreasonable to require States to impose control 

requirements on low-reactivity VOC like ethanol or methanol where it will make little difference 

in an area’s ability to achieve the ozone standard and potentially aggravate an ozone problem by 
113

increasing NOx as a result of incinerating VOC. The commenter believed that it would be 

particularly arbitrary and unreasonable to penalize states that failed to control such minimally 

reactive VOC if it were technically feasible and cost-effective to reduce higher reactivity VOC or 

NOx from other sources. Commenter (0151) urged the EPA to amend 40 CFR § 51.1112 to 

clearly articulate a legal basis for use by the states of the RACT flexibility.

Commenter (0151) further stated, the EPA should “codify” its views on “VOC reactivity” to 

discourage states from regulating sources of VOC that are marginally reactive. 

Response: The EPA recognizes that modification of the existing guidance on determining RACT 

could add flexibility that would be beneficial to the efficiency of ozone controls in some states. 

Several Commenters provided examples where photochemical modeling suggests that ozone 

formation in some areas is NOx limited, such that changes in anthropogenic VOC emissions will 

have little effect on ozone concentrations. We agree that there appears to be scientific support for 

the existence of NOx-limited nonattainment areas. Additionally, we agree that from a practical 

standpoint, modification of the existing guidance on determining RACT could add flexibility that 

would be beneficial to the efficiency of ozone controls in some states. 

However, the Commenters supporting flexibility presented legal arguments that, the EPA does 

not currently view as sufficient to address potential statutory restrictions. The main legal 

arguments presented by Commenters in support of flexibility argue that, the EPA has 

“discretion” to determine what constitutes “reasonably” available control technology. However, 

the EPA is concerned that it may not have sufficient discretion to support this option. Section 

182(b)(2) provides that SIPs must “require the implementation of RACT” with respect to “VOC

sources.” It does not clearly authorize consideration of whether technology that is “reasonably 

available” is also reasonably effective with respect to improving air quality or reducing ozone 

formation, and it does not specify criteria for discerning a level of air quality improvement below 

which available technology does not need to be implemented. Moreover, as noted by a 

Commenter, Congress has shown that when it intends Subpart 2 to allow exceptions based on air 

quality benefit considerations it knows how to say so expressly. See e.g. section 182(f), (allowing 

the EPA to waive certain NOx reduction requirements where such reductions will not provide 

“net air quality benefits.”). Thus, we agree with the Commenters finding it significant that 

182(b)(2) contains no comparable language. The EPA’s analysis is further informed by our 

recognition that the provisions of Subpart 2 of the CAA Subpart D generally reduce agency 

discretion in determining how to implement the Act. See Whitman v American Trucking Assoc., 

531 U.S. 457, 484 (2001). 

The EPA is not prepared at this time to establish a specific definition for “negligible effect.”

Additionally, given the concerns raised by Commenters about whether the CAA authorizes such 

an approach, the EPA is not at this time revising our long-standing RACT determination 

guidance. The EPA may continue to explore this option and potential legal support for it in the 

future.

We also note that we received information from Commenters that may be useful in evaluating 

the definition of “negligible effect,” which we will consider in the future as we further assess 
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whether to modify the existing RACT guidance.

Comment: Do not support consideration of the limited impact of VOC controls

Commenters (0146, 0163, 0168, 0177 and 0180) urged the EPA to remove the option for states 

to consider air quality impacts when performing VOC RACT analyses. 

Commenters (0146 and 0177) stated that, since many states have expended considerable 

resources to adopt RACT and CTG rules, if the EPA were to allow this proposed circumvention 

of mandatory CAA requirements, it will exacerbate an already inequitable distribution of clean 

air costs; i.e., there are significant equity issues that the EPA should consider. 

Commenters (0168, 0177 and 0180) stated, the EPA has issued NOx waivers in the past and this 

appears to be setting up some type of VOC waiver scheme, which the Commenters do not 

support. Commenter (0180) stated that, where Congress intended to allow exceptions based on 

air quality benefit considerations it has expressly said so, as in section 182(f); however, no such 

exception appears in, or applies to, section 182(b)(2).

Commenter (0177) pointed out that, in the Phase 2 Rule for the 1997 NAAQS, the EPA 

responded to a comment urging the EPA to expand the waiver provisions of section 182(f) to 

VOC RACT as well as NOx RACT (70 CFR 71662; 11/29/2005), saying: “We [EPA] do not see 

any provision in the CAA that would give us the authority to create such an exemption. While 

Congress could have created a VOC waiver at the same time the section 182(f) NOx waiver 

provisions were enacted, Congress chose not to do so.” Commenter (0177) also stated that, the 

EPA went on to note that the congressionally required CAA section 185B study conducted by 

the National Academy of Sciences concluded that, unlike NOx, “‘control of VOC never leads to 

a significant increase in ozone.’ Thus, the section 185B report does not support a waiver 

provision for VOC.” 

Commenters (0146, 0163, 0168 and 0177) stated that, the CAA requires RACT on all major 

sources of VOC in nonattainment areas and the Commenters do not believe that, the EPA has the 

authority to eliminate this requirement. 

Commenter (0163) stated, this "flexibility" would effectively make the subpart 2 RACT 

requirements the same as the subpart 1 RACM/RACT requirements. Commenter (0163) cited 

South Coast, where the EPA was instructed not "to render Subpart 2's carefully designed 

restrictions on EPA discretion utterly nugatory," nor could it "construe the statute in a way that 

completely nullifies textually applicable provisions meant to limit its discretion." ld. at 484-85. 

Commenter (0177) stated that, the plain text of the CAA and the EPA’s previous interpretations 

of it make it clear that RACT is a required control level for specific sources, with no direct link 

to a level of ozone improvement or to any required demonstration of attainment. Commenter 

(0177) stated, RACT/CTGs are a minimum control requirement for specific areas and 

consideration of related ozone improvements should continue to be restricted to any additional 

RACM measures needed to achieve attainment. 
115

Commenter (0180) stated, the EPA does not have the discretion to override Congress’ mandate 

based on the agency’s belief that such controls are not warranted or that controlling other 

pollutants would be better policy. Commenter (0180) stated that, Congress could not have been 

clearer that VOC RACT is mandatory for all of the referenced source categories and sources.

Commenter (0180) stated that, a key feature of the 1990 Amendments to the Act was Congress’ 

decision to supplement the Act’s prior focus on air quality results (an approach that had often 

failed to produce timely attainment) with explicit requirements for emission reductions.

Commenter (0180) stated, the EPA and states cannot circumvent the clear Congressional 

commands in section 182(b)(2) via the artifice of claiming that the economic feasibility of 

further VOC controls depends in part on the air quality benefit of such controls. Commenter 

(0180) stated that, not only has Congress made clear that section 182(b)(2)’s mandates for VOC 

RACT are not limited by any sort of air quality benefit test, but the plain meaning of “economic 

feasibility” does not have anything to do with air quality benefits, citing several cases.

Response: The EPA thanks the Commenters for their thoughtful comments. Given the concerns 

raised by Commenters about whether the CAA authorizes such an approach, the EPA is not at 

this time revising our long-standing RACT determination guidance. Therefore, states should 

continue to rely on existing guidance when developing their RACT SIPs. The EPA may continue 

to explore this option and potential legal support for it in the future. 

Comment: Clarify consideration of the limited impact of VOC controls

Commenter (0150) urged the EPA to clarify that, this concept is only to be used where a state 

determines that VOC reductions as a whole are not needed, not in determining whether an 

individual source or source category makes "negligible" contributions to the area's emissions. 

Response: The EPA is not finalizing revised RACT guidance for the 2008 ozone NAAQS. 

Therefore, states should continue to rely on existing guidance when developing their RACT 

SIPs. 

8. MACT 

Comment: SIP credit for MACT measures

Commenter (0151) suggested that, before requiring states to apply NOx RACT to all combustion 

sources, the EPA should study certain MACT rules and specifically recommend the SIP credit 

for federal MACT measures in SIP planning. Commenter (0151) stated, that Mercury and Air 

Toxics Standards (MATS) compliance in the next 2 years is likely to force utilities to repower a 

sizeable portion of the existing utility fleet and may provide, significant NOx reductions, even 

though NOx reduction is not the goal of either CAA section 112 rule. These reductions should be 

well within the time allotted for implementation of creditable reductions for SIP-planning, 

although anticipated delays in implementation for grid reliability may occur. Commenter (0151) 

suggested that, before requiring states to apply NOx RACT to all combustions sources, the EPA 

should study this issue and specifically recommend the SIP credit for federal MACT measures in 
116

SIP planning. That study should also discuss the consequence of any delays in implementation 

under the MACT and the EPA’s MATS Administrative Consent Order Policy allowing certain 

facilities an extra year for compliance. 

Commenter (0159) agreed with the EPA's position and supported allowing states to rely on 

MACT standards for the purpose of demonstrating that a source has met VOC RACT. 

Response: States can rely on emission reductions from federal control measures (including the 

MACT rules) to help areas attain the 2008 ozone NAAQS or to meet other SIP-related 

objectives, as long as the federal measures achieve their reductions prior to the relevant SIPrelated deadlines. Regarding the issue of whether to specifically recommend the SIP credit for 

federal MACT measures in SIP planning, the EPA is not planning at this time to develop specific 

recommendations for SIP credit for Federal MACT measures. Additionally, we note that 

regardless of whether or not the EPA conducts such a study, the RACT requirements remain 

requirements that must be met under the CAA, whether through reliance on MACT or otherwise.

The EPA agrees with the Commenter that supported allowing states to rely on MACT standards 

for the purpose of demonstrating that a source has met VOC RACT. We note, however, that 

states should ensure that any MACT controls relied on for RACT adequately address all VOC 

and not just those that are also HAPs.

Comment: Municipal Waste Combustors

Commenter (0177) stated that, the EPA should act to move forward with the analysis needed to 

determine appropriate revisions to the municipal waste combustors (MWC) MACT, preferably 

before the end of 2013 so that states can take them into account when preparing RACT analyses. 

Commenter indicated that, if further delays occur in the issuance of MACT limits, states may be 

faced with modifying regulations twice to comply with both the MACT and RACT requirements.

Response: Although the agency remains committed to addressing issues raised in the remand, 

we currently have no specific schedule to develop a new proposal for MWCs.

9. RACM in areas that are NOx-limited

Comment: Commenter (0130) suggested amending RACM guidance to follow the same 

common-sense approach proposed for RACT; i.e., if studies show that reducing anthropogenic 

VOC emissions in an area has little effect on ground-level ozone concentrations, RACM 

analyses should not be required for that pollutant.

Response: In order for states to demonstrate attainment of a standard, the EPA’s long-standing 

policy has been that states must address whether there are RACM that may advance the 

attainment date. (See memorandum titled, “Additional Submission on RACM from States with 

Severe 1-hour Ozone Nonattainment Area SIPs,” John Seitz, December 14, 2000). Additionally, 

existing EPA guidance already provides some assistance to states with identifying the type of 

measures that might be considered for RACM (See General Preamble, 57 FR 13549, April 16, 
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1992). If a state demonstrates that implementation of VOC emission reduction measures will not 

contribute to an area’s RFP or to attainment, then additional control of VOC emissions does not 

need to be considered for RACM purposes. Thus, the EPA concludes that it need not amend 

RACM guidance to address this comment.

E. Does the 2008 ozone NAAQS result in I/M programs?

1. Do not support check engine light proposal 

Comment: Commenter (0128) stated that, the idea that states could meet their NAAQS 

requirements through programs that offer vehicle owners free or subsidized repairs of vehicles 

with lit “Check Engine” lights is inconsistent with the purpose and function of auto insurance 

and urged the EPA to remove this suggestion from future iterations of the proposal. The 

commenter stated that the EPA’s proposal suggests that states could meet their NAAQS 

requirements through programs that offer vehicle owners free or subsidized repairs of vehicles 

with lit “Check Engine” lights. The commenter further indicated that the EPA proposed that the 

choice of how to fund these repairs would rest with the state, but could include “requiring 

vehicle insurance providers ... to cover the cost of repairing the vehicle when the ‘Check Engine’ 

light comes on.” The commenter believed this idea is inconsistent with the purpose and function 

of auto insurance and the commenter urged the EPA to remove this suggestion from future 

iterations of the proposal. (0128)

The commenter also stated that auto insurance, like all property and casualty insurance, provides 

coverage for fortuitous losses, such as those incurred when a vehicle is involved in a collision. It 

is not designed and was never intended, to provide for upkeep and maintenance. The commenter 

pointed out that the responsibility for “Check Engine” repairs, and the maintenance to avoid 

them, rest with a vehicle’s owner. The commenter believed that if this obligation is removed, or 

shifted to an insurance company, a moral hazard could be created where owners could simply 

neglect to maintain their vehicle with the knowledge that the costs of doing so would be borne by 

others. The commenter further stated their understanding that automobile insurance is provided 

based upon actuarial research into the statistical likelihood that a driver and a vehicle may be 

involved in a collision resulting in property or physical damages. The commenter believed that 

there are no existing actuarial models or processes for insurance companies to effectively 

evaluate and price any insurance policies that cover the maintenance and repairs of vehicles that 

are not a result of a collision resulting in property or physical damages. The commenter 

concluded that developing and implementing such standards would further increase the costs of 

providing insurance coverage and therefore raise the insurance rates for all drivers. The 

commenter further believed that the increased expense of coverage could have the unintended 

consequence of inducing more drivers to forgo having vehicle insurance. The commenter 

indicated that uninsured motorists already present a significant cost for insurance consumers, and 

this rule could exacerbate the problem. The commenter added a similar concern that drivers may 

opt to carry only liability coverage rather than collision/comprehensive coverage in response.

Response: The EPA did not propose and does not intend to propose to require either that states 

mandate or that insurance companies offer such an alternative to I/M. Instead, the EPA was 
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providing an example of one potential approach to achieving needed vehicle emission repairs 

that doesn’t rely on traditional, periodic I/M testing. The EPA notes that some insurers are 

already accessing vehicles’ OBD systems to provide – for example – safe driver insurance based 

upon data gathered from the OBD system for that specific vehicle and driver. The EPA believes 

that such insurance companies may have access to the data needed to determine whether offering 

coverage (or an extended warranty package) for OBD-triggered repairs would make business 

sense and, if it does, to then work with the I/M states in which they operate to accept such 

coverage as an alternative means of complying with the I/M requirement, but the EPA does not 

anticipate such coverage being a required element of insurance. 

2. Alternative I/M programs

Comment: Commenter (0137) encouraged the EPA to provide the flexibility to substitute 

programs or requirements in place of I/M programs when they can be shown to be more 

beneficial and cost effective. The commenter stated that according to the implementation 

requirements, no new I/M programs are required as a result of the 2008 ozone NAAQS; 

however, new mandatory programs could be necessary due to future ozone standards. The 

commenter indicated that while EPA explains in the implementation rule that today’s I/M 

programs are less expensive and easier to administer due to advances in technology, these 

programs still require significant state resources. The commenter added that advances in 

emissions control technology and fleet turnover, which will only continue over time, have 

lessened the effectiveness of these programs. For this reason, the commenter encouraged the 

flexibility to substitute programs or requirements in place of I/M programs when they can be 

shown to be more beneficial and cost effective.

Commenters (0144, 0146) supported the flexibility proposed by the EPA in designing alternative 

I/M programs, but also expressed concerns. The commenter stated that any alternative design 

must meet the appropriate I/M performance standard for the area. The commenter suggested that 

the EPA should provide guidance on how to calculate the benefits of such alternative designs to 

enable states to evaluate options and demonstrate that they meet the performance standards. The 

commenter appreciated the EPA’s willingness to be flexible regarding alternative I/M programs, 

including using OBD-only emissions testing and telematics and no longer requiring tailpipe 

testing for applicable fleets. However, the commenter believed that any alternative I/M program 

approach must be consistent with CAA and any areas with new I/M programs should be treated 

with the same rigor as areas with existing I/M programs. The commenter stated that while 

advances in technology often afford new approaches to existing problems, any innovative 

program structure must be accompanied by guidance indicating minimum requirements to assure 

that the program’s emission reductions are real, quantifiable and enforceable. Commenter (0146) 

suggested that the EPA must also ensure that its mobile source emissions model (e.g., MOVES) 

is updated to better simulate the impacts of any alternative I/M programs. Commenter (0146) 

believed that the EPA’s proposed I/M program alternatives introduce issues that must be 

addressed to ensure that any alternative program design meets performance standards. The 

commenter stated that the EPA’s specific suggestion that I/M programs that do not rely on 

required testing would be considered adequate is problematic. The commenter believed that the

EPA’s discussion is cursory and does not address significant implementation issues, including 
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vehicle tampering, motorist compliance and enforcement, program efficacy and potential 

regulatory conflicts in cases where EPA suggests other agencies assist in implementing the 

program. Moreover, the commenter believed that the EPA’s proposed voluntary program 

overlooks that higher failure rates typically occur when enhanced I/M programs are first 

implemented and decline as vehicle owners and repair technicians learn what level of 

maintenance or repair is required to pass the periodic tests. The commenter concluded that the

EPA’s proposed metric for calculating equivalency, is therefore inappropriate and suggested that 

when designing alternatives, the EPA should consider appropriate incentives for motorists to 

better maintain their vehicles and seek repairs as failures occur. The commenter urged the EPA 

to ensure that such issues are addressed through a separate I/M rulemaking.

Commenter (0179) believes that, states should have maximum flexibility when developing an 

I/M program. Commenter believes that, the current state program in North Carolina takes a 

reasonable approach, but recognized that future improvements in vehicle technology and 

communications software could open up other possibilities that could cost effectively achieve 

I/M’s primary goal of reducing emissions from the fleet in-use.

Response: In its discussion of I/M flexibilities and alternatives available to existing and future 

I/M programs in the preamble to the SIP Requirements proposal, the EPA was not proposing 

changes to the I/M rule to enable these flexibilities. Rather, these are flexibilities currently 

available under the I/M rule as promulgated. Specifically, the I/M rule states:

... Equivalency of the emission levels which will be achieved by the I/M program design 

in the SIP to those of the model program described in this section shall be demonstrated 

using the most current version of EPA’s mobile source emission model, or an alternative 

approved by the Administrator, using EPA guidance to aid in the estimation of input 

parameters. States may adopt alternative approaches that meet this performance 

standard. States may do so through program design changes that affect normal I/M input 

parameters to the mobile source emission factor model, or through program changes 

(such as the accelerated retirement of high emitting vehicles) that reduce in-use mobile 

source emissions... 

40 C.F.R. 51.351(d) (emphasis added). Thus, the I/M Rule provides that alternative approaches 

that change the in-use fleet in such a way as to reduce the emissions of the in-use fleet by an 

amount equal to or greater than the applicable performance standard can be considered as 

acceptable alternatives to or supplements for the otherwise applicable I/M program. As discussed 

in the preamble to the proposed SIP Requirements rule, EPA believes that mobile source control 

measures like vehicle repair incentives, accelerated fleet turnover, remote OBD testing and repair 

and even as-yet unthought-of mobile source controls have the potential to meet this definition of 

“alternative approaches.” It is up to the states to innovate in this regard, and the EPA will judge 

whatever proposals may come on a case by case basis. At the same time, I/M is a statutorilymandated requirement, and the EPA does not believe it has authority to waive I/M requirements 

in exchange for states adopting programs in a SIP that do not achieve equivalent reductions in 

emissions of the in-use fleet, as those cannot be considered an alternative approach to meeting 

the performance standard for I/M.
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It should also be stressed that while this flexibility to demonstrate the equivalency of alternative 

approaches exists in the I/M rule as currently written, such flexibility is an allowance and not a 

requirement. Traditional I/M programs like those currently approved in individual SIPs are under 

no obligation to change, and potential new I/M program areas under future standards will 

continue to have the option to adopt traditional I/M programs Furthermore, it should be noted 

that – contrary to Commenters’ claims – the effectiveness of I/M testing has not lessened over 

time. I/M tests are still successfully identifying vehicles in need of repair. It is just that the 

number of vehicles needing repair has gone down as newer vehicles are staying cleaner, longer, 

so that the amount of excess emissions available for I/M to reduce has gotten smaller.

Regarding the suggestion that the EPA develop guidance on I/M alternatives, the agency has no 

plans at this time to develop guidance (or separate modeling options) for determining the 

equivalency of alternatives, given the number of alternatives and variations on alternatives which 

may or may not ever be adopted by actual program areas. Again, the flexibility to innovate in 

this regard exists in the I/M rule, but it is up to individual states to seize and make the best of this 

opportunity. EPA, in turn, will work with such states to assess the potential their proposed 

alternative approaches on a case-by-case basis to assure that the requirements of the I/M Rule are 

met.

Regarding the observation that existing I/M program areas and future I/M areas be treated 

equally, the EPA believes that any flexibility available to new I/M areas will be equally available 

to existing I/M areas. The EPA acknowledges that it may not be practical for some existing I/M 

programs to take immediate advantage of these flexibilities, due to contracts, equipment 

investments, or simply having an older-than-average in-use fleet requiring tailpipe testing longer 

than would otherwise be necessary, but these factors and considerations are the prerogative of 

the states designing I/M programs. 

3. Substitute for I/M program

Comment:

Commenter (0172) did not support any I/M requirement, despite the EPA’s preamble discussion 

of how the modern I/M program is much improved over the original program and the use of 

alternative programs for vehicle testing. Commenter recommended that, the EPA cite Executive 

Order 13563, “Improving Regulation and Regulatory Review,” for the same common sense 

approaches cited in other instances of the proposal to evaluate equivalent methods beyond I/M.

Commenter (0146) stated, the EPA should ensure equity among nonattainment areas, and not 

treat new nonattainment areas differently than current nonattainment areas by allowing the use of 

non-I/M emission reductions to meet I/M program requirements.

The commenter believed that the language of the CAA is clear with respect to requiring vehicle 

I/M programs and that over the years, many nonattainment areas have successfully implemented 

I/M programs, and the resultant emissions reductions and public health protections have been 

substantial. The commenter believed that technical advances since 1990 provide for much more 
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streamlined, cost-effective, publicly-acceptable I/M programs and the on-board diagnostic 

(OBD) approach to I/M is straightforward and provides significant flexibility in terms of 

program design, oversight and enforcement. The commenter urged the EPA to focus on 

alternative I/M program approaches, rather than on alternatives to the I/M program. Moreover, 

the commenter expressed concern that some of the EPA’s proposed approaches, as articulated in 

the draft rule, are not well developed. The commenter urged the EPA to reconsider these 

approaches as well as develop new approaches, provide technical support for any proposed 

approaches and vet them through a separate I/M rulemaking process, where they can undergo 

more rigorous scrutiny and review. The commenter stated that the EPA’s backsliding provisions 

require that existing nonattainment areas maintain their I/M programs and stated that the EPA 

should ensure equity among nonattainment areas and not treat new nonattainment areas 

differently than current nonattainment areas by allowing the use of non-I/M emission reductions 

to meet I/M program requirements.

Commenter (0177) disagreed with the EPA’s assertion in the proposed rule (pg 34180) that 

Inspection and Maintenance (I/M) programs may no longer be relevant because of technological 

advances or alternative solutions. The Commenter stated that, as the proposed rule 

acknowledges, (pg 34195) I/M programs are much easier to implement than in the past and 

remain important in controlling motor vehicle emissions, which continue to be a large 

contributor to the ozone problem. While the overall light duty fleet is cleaner than in the past, 

there remains a significant gap between well-maintained vehicles and malfunctioning grossemitting vehicles that can best be identified through mandatory I/M inspections. The Commenter 

suggested that, the EPA should be consistent in its message about I/M programs in new 

nonattainment areas and require that all I/M programs meet applicable I/M performance 

standards consistent with the requirements of the CAA and the EPA’s I/M regulation. (0177)

Response: As discussed previously, the flexibility to substitute mobile source emission 

reductions equal to or greater than those that would be achieved by an I/M program meeting the 

relevant performance standard already exists in the I/M rule as promulgated. It is only recently 

that technologies (like OBD) have become so widely available as to make alternative programs 

like those discussed in the preamble (and allowed by this existing flexibility) feasible. Also as 

previously discussed, this existing flexibility is equally available to both existing and future I/M 

program areas.

4. Flexibility needed for future I/M programs 

Comment:

Commenter (0141) encouraged the EPA to review the possibilities for flexibility for this 

requirement in the future. The Commenter stated that, whereas the EPA concludes no additional 

I/M programs are required under the 2008 standard, we are concerned with the continued cost 

effectiveness of this program in the future if the EPA tightens the ozone standard in the 

2014/2015 time frame. In Ohio, I/M is currently required in the Cleveland area. The cost of this 

program is met with general revenue funds in the state budget; individuals are not charged for the 

test. The Commenter stated that, the annual cost of the program exceeds the state collections of 
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title V fees. The Commenter expressed concern that, this cost would be expanded in the future if 

additional areas are required to implement I/M. At some point the EPA needs to review the 

possibilities for flexibility for this requirement in the future. (0141)

Commenter (0164) requested the EPA to consider a more holistic approach when incorporating 

emerging vehicle innovations such as safety measures that avoid vehicle collisions altogether, 

fuel economy technologies and multi-pollutant emissions controls that achieve the lowest 

emissions possible.

Response: As previously discussed, the EPA believes that the flexibility already exists for I/M 

areas – whether existing or future – to adopt alternative mobile source control programs, 

provided these alternatives achieve the same or better emission reductions from in-use mobile 

sources as would be achieved by implementing an I/M program meeting the relevant 

performance standard.

5. Onboard diagnostic (OBD) testing 

Comment: Commenters (0143, 0163 and 0168) supported the EPA proposal to use OBD testing.

The commenter agreed DEP agrees that OBD testing should be the I/M Program of choice for 

any areas that are required to start an I/M program in the future. OBD testing has proven to be an 

efficient, cost-effective means for reducing emissions. Tailpipe testing is fast becoming obsolete 

as pre-1996 model year vehicles and vehicles that are not equipped with OBD systems but are 

subject to I/M testing are being replaced with OBD-equipped vehicles. (0143)

Commenter (0163) indicated that the preamble stated that modern I/M is vastly different 

and simpler than the I/M programs of 20 years ago. New York agrees that I/M programs 

no longer need to use tailpipe testing and has promulgated OBD or “Check Engine Light” 

testing regulations for motor vehicles throughout New York State. The commenter 

believed that these new programs can be designed to be equivalent to previous I/M 

programs. The commenter believed that the EPA has correctly characterized the 

advantage of OBD technology in the proposal - OBD offers vehicle owners all the 

information they need regarding whether or not their vehicle will pass or fail an I/M 

inspection and provides for a multitude of simplified inspection options. The commenter 

believed that on-road mobile emissions have decreased significantly due to vehicle 

emission controls, and OBD technology is a means to ensure these controls are repaired 

when they fail. 

Response: The EPA agrees, but notes that for some existing I/M areas with older-than-average 

in-use fleets, it may be necessary to continue tailpipe testing of vehicles model year 1995 and 

older longer than would be the case for areas with average or newer than average aged fleets.

Comment: Commenter (0164) requested that, the EPA take a leadership position in quantifying 

OBD test results and enhance the program from its current PASS or FAIL status. The commenter 

believed that estimates of emissions readings may be possible and helpful to the driving public. 

The commenter believed that a gap exists in knowing emission levels of MY1996 and newer 
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vehicles. The commenter believed that current PASS and FAIL readings make it difficult to 

accurately quantify impacts of high emitting vehicles in the overall on-road mobile source 

apportionment and emission reduction benefits of vehicle repairs or replacements.

Response: The EPA collaborated with industry experts to investigate the possibility of 

developing a separate method for translating OBD-based repairs on individual vehicles into 

specific levels of mass emission reductions but was unable to identify an adequate surrogate for 

paired testing of the vehicles in question using OBD and a mass-emissions test like the IM240 or 

Federal Test Procedure (as originally required under the 1992 I/M rule). Nevertheless, the EPA 

believes that existing guidance for performing I/M program evaluations using alternatives to 

paired mass-emissions testing – including overall fleet characterization methods addressed in 

that existing guidance – is adequate for areas to meet the CAA’s program evaluation testing 

requirement.

6. Support acceleration simulation mode (ASM) testing 

Comment: Two Commenters (0156 and 0164) disagreed with the EPA’s recommendation that 

acceleration simulation mode (ASM) testing of 1995 and older gasoline vehicles no longer be 

required as part of a state’s I/M program.

Although in North Central Texas, during calendar year 2012, 93 percent of all emissions 

inspections were OBD II tests and approximately 6 percent were ASM tests, the failure 

rate for OBD II tests was only 4 percent while the failure rate for ASM tests was nearly 

11 percent. Although the EPA estimates that about 80 percent of the national vehicle fleet 

is already equipped with an OBD II system, there are still significant emissions 

reductions to be gained by testing and repairing or retiring pre-OBD II vehicles. Weatherrelated benefits extends the design life of roadway vehicles in our region resulting in a 

lower share of ASM tests. (0164)

The EPA mentions the equipment needed for ASM testing, dynamometers, is expensive, 

but as of August 2013, 1,053 stations in North Central Texas still have functioning 

dynamometers and are capable of conducting ASM testing. NCTCOG can appreciate 

EPA’s justification for discontinuing ASM testing, but requests this only apply to areas 

launching new I/M programs. For areas already performing ASM testing, NCTCOG 

requests the EPA keep this requirement until the time at which ASM vehicles leave the 

program through either natural or expedited attrition. (0164)

Based upon analysis of emissions data collected from both State emissions testing and 

remote sensing, a failing ASM vehicle emits one-and-a-half times as much nitrogen 

oxides (NOx) emissions as a failing OBD II vehicle. In addition, according to a Texas 

Commission on Environmental Quality (TCEQ) study conducted in 2010, the I/M 

program yields nearly a 5 ton per day reduction in NOx emissions and 4.3 ton per day 

reduction in hydrocarbon (HC) emissions in DFW from the testing of ASM vehicles 

alone. If ASM is allowed to be omitted from the program, these reductions will be lost 

and additional measures will have to be implemented to offset them. 
124

Despite State photochemical modeling consistently showing attainment of the ozone 

standard, the DFW region continues to be in nonattainment year after year. The region 

cannot afford to lose real world emissions reductions even if the model shows little 

emissions reductions or few SIP credits to be gained. Thus, NCTCOG implores the EPA 

to consider emissions benefits associated with each ASM test as the driving factor on 

whether or not to include them in the I/M program and not the cumulative effect of ASM 

testing, which is strictly the result of a smaller fleet size. In Texas, vehicles 24 years old 

and older are exempt from the emission test due to low mileage accumulation; therefore, 

the EPA has a built in sunset provision that already exists. (0164)

Local jurisdictions should be able to claim emission reductions needed for attainment 

demonstrations. According to a 2010 TCEQ study, ASM vehicles were responsible for 

nearly 5 tons/day reduction of NOx and 4.3 tons/day reduction of hydrocarbon emissions 

in just one ozone nonattainment area. As of August 2013, over 1000 stations could still 

perform ASM testing in this area. If these reductions cannot be claimed, additional 

control measures would be needed to offset those lost reductions. In 5 years, pre-OBD

vehicles will be 24 years old and will be exempt from tail-pipe testing at which time I&M 

programs can become OBD only. ASM remains a beneficial emission reduction option 

for local areas. (0156)

Response: The EPA did not suggest, recommend, or propose that areas needing the emission 

reductions achieved by tailpipe testing (like the ASM) drop such testing. As previously 

discussed, some areas of the country with older-than-average in-use fleets may need to retain 

tailpipe testing for a period of time, although as a general matter, the level of emission reductions 

achievable from testing these older vehicles is naturally shrinking as the fleet turns over. It is up 

to individual states to determine if and when the amount of emission reductions achievable 

through any of the several tailpipe tests available is worth the investment.

7. Incorporation of Diesel Vehicles in I/M Program 

Comment: Commenter (0164) recommended that, the EPA allow credits for NOx emissions 

testing of OBD II compliant diesel vehicles as part of the state’s I/M program. 

Diesel powered vehicles less than 8,500 lbs gross vehicle weight rating (GVWR) have 

been equipped with OBD II systems since model year (MY) 1997; vehicles between 

8,500 lbs and 14,000 lbs have been equipped starting with MY2004; and vehicles greater 

than 14,000 lbs began being phased-in in MY2010. While studies show real-world 

emissions benefits to be gained by implementing a diesel I/M program, Texas has thus far 

held off on implementing such a program due to not being able to claim any additional 

SIP credits for doing so. Thus, NCTCOG requests the EPA’s assistance in providing a 

mechanism for claiming SIP credits for a diesel I/M program to help overcome this 

hurdle. The emissions benefits associated with each diesel test should be the driving 

factor on whether or not they are included in the program; not the cumulative effect 

which is strictly the result of a smaller but growing, fleet size. And, while the magnitude 
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of emissions from light-duty diesel vehicles does not compare to that of light-duty 

gasoline vehicles, the inclusion of such vehicles in an I/M program may help minimize 

the public perception that diesel vehicle owners do not equally contribute to regional 

efforts to improve air quality. (0164)

Response: The issue of SIP credit for OBD testing of OBD-equipped diesel vehicles was not one 

of the areas discussed in the I/M section of the 2008 8-hour ozone SIP Requirements proposal. 

The EPA does not have the before and after repair mass emissions data needed to establish 

possible SIP credit for testing and repairing these vehicles. Furthermore, such vehicles are either 

too few or too new to warrant the investment it would take for the EPA to gather such data at this 

time. Nevertheless, I/M program areas that believe there are real world benefits to be achieved 

by conducting OBD testing on diesel vehicles are free to pursue such testing, though the EPA 

recommends that states observe best practices with regard to testing such vehicles.19

Furthermore, the EPA remains open to any state or program area wishing to make a technically 

and legally defensible case for assigning SIP credit for these tests. . 

8. Funding for Vehicle Repair and Replacement Programs 

Comment: Commenter (0164) supported the EPA’s suggestion to consider implementation of a 

vehicle repair and replacement assistance program, but recommends it be a complement to the 

I/M program and not in lieu of an I/M program as proposed. 

The Low-Income Vehicle Repair Assistance, Retrofit and Accelerated Vehicle 

Retirement Program (LIRAP) is a light-duty repair and replacement assistance program 

that has been implemented successfully in Texas in years past. In Texas, fees are 

collected through emissions testing and are dedicated specifically for administering this 

program. The successful I/M program drives the market for repair and replacement of 

vehicles and is necessary to enforce federal involvement in advancing fleet turnover. 

(0164)

Response: The EPA encourages low-income repairs assistance programs as a way of reducing 

program avoidance on the part of vehicle owners statistically most likely to fail the test (and 

financially least likely to be able to afford the burden of vehicle repairs). As such, the EPA 

agrees that an assistance program like LIRAP is an appropriate supplement to the existing I/M 

program, while not itself constituting an adequate replacement for the program. For a repair 

assistance program to replace I/M, it would need to assure that as many vehicles would be 

repaired as would be the case under the I/M program. To make such a demonstration, it is 

unlikely that the program could rely only on low-income vehicle owners. Instead, the repair 

 

19 Best practices for such testing are detailed in the best practices document available at the 

following web address: http://obdclearinghouse.com/index.php?body=obdinformation.
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subsidy would have to be more generally available, based upon the level of emission reduction 

achievable from repairing a given vehicle, as opposed to the income level of the owner.

9. Separate rulemaking needed for I/M 

Comment: Commenters (0146 and 0177) stated, the EPA should defer to a more thorough and 

separate I/M program rulemaking process concerning I/M flexibility.

NESCAUM members recognize the importance and continued relevance of I/M in 

controlling motor vehicle emissions. We agree with the EPA that significant 

technological advances, including the diminishing relevance of tailpipe testing and 

widespread implementation of OBD programs, have occurred and that practical 

flexibility is warranted for the future. The NESCAUM member agencies, however, are 

concerned with the example programmatic changes that the EPA has offered in this 

rulemaking. We urge the EPA to carefully consider the CAA requirements and the 

existing I/M performance standards in judging the merits of these concepts. Clearly, the 

EPA should develop modeling guidance for such alternatives if deemed feasible. As such, 

NESCAUM believes the EPA should defer to a more thorough and separate I/M program 

rulemaking process concerning I/M flexibility. (0146)

NESCAUM disagrees with the EPA’s assertion that I/M programs may no longer be 

relevant because of technological advances or alternative solutions. These programs are 

much easier to implement than in the past and remain important in controlling motor 

vehicle emissions. Modeling shows that emissions from the on-road sector remain 

significant for the ozone problem. While individual vehicle emissions have been 

substantially reduced and the overall light duty fleet is cleaner, there still remains a 

significant gap between well-maintained vehicles and malfunctioning gross-emitting 

vehicles that would be identified through mandatory I/M inspections. The EPA should be 

consistent in its message about I/M programs in new nonattainment areas: all I/M 

programs must meet applicable I/M performance standards consistent with the 

requirements of the CAA and the EPA’s I/M regulation. (0146)

Response: As discussed previously, the flexibility to substitute mobile source emission 

reductions equal to or greater than those that would be achieved by an I/M program meeting the 

relevant performance standard already exists in the I/M rule as promulgated. It is only recently 

that technologies (like OBD) have become so widely available as to make alternative programs 

like those discussed in the preamble (and allowed by this existing flexibility) feasible. Also as 

previously discussed, this existing flexibility is equally available to both existing and future I/M 

program areas. The EPA notes that the approval of any specific program as meeting the 

requirements of the I/M Rule would be accomplished through notice and comment rulemaking 

on a state’s proposed revision to its SIP.

10. Timing of I/M SIP 
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Comment: Commenter (0143) supported the EPA proposal to align Vehicle Inspection and 

Maintenance (I/M) programs and attainment SIP deadlines. The Commenter stated that, on April 

7, 2006, the EPA finalized a suite of revisions to the I/M rule to address the implementation of 

I/M under an 8-hour ozone NAAQS (71 FR 17705). The revised rule included deadlines for 8-

hour ozone nonattainment areas that were tied to the effective date of a given area’s designation 

and classification under the 8-hour ozone NAAQS. The deadlines for implementing an I/M 

[program] are reasonable in that a nonattainment area that does not currently have an I/M 

program, that would be required to implement one, would have 4 years after the effective date of 

designation and classification to begin testing vehicles. (0143)

Commenter (0163) recommended that, the EPA not make any changes to the I/M SIP deadlines 

that are inconsistent with the deadlines prescribed in the CAA.

Commenter (0177) stated that, any contemplated changes in deadlines for submittal of I/M SIP 

revisions should be legally justified and in no case should result in delays in required I/M 

program implementation.

Commenter (0179) requested that, states be given the option of deciding on the timing of an I/M 

SIP submission based on their individual circumstances. The Commenter stated that, in the 

proposal, the EPA identified alterative implementation options to modernize I/M programs from 

the last time new I/M programs were required. In order to pursue such options, the Commenter 

stated that, states will need time to analyze various I/M program designs to determine which 

combination of program parameters is capable of meeting the emission reduction needs of the 

attainment SIP, present the concept to stakeholders, seek the appropriate legal authority from 

legislative bodies and adopt a rule which could take 1-2 years to undergo a state’s administrative 

process.

Response: The EPA’s proposal to align the I/M SIP submittal deadline with the deadline for 

submitting the attainment demonstration will not impact the emission reductions achieved 

through the I/M requirement because the proposal does not change the deadline by which new 

I/M areas would need to begin testing and fixing vehicles. Further, the EPA believes that it is 

required to interpret the Act’s I/M SIP submission deadlines for basic I/M SIPs because the 

CAA’s requirement of “immediately upon enactment” for these SIPs is impossible to meet. 

Additionally, the EPA sees no reason why basic and enhanced I/M programs should be put on 

different schedules, as the difference between basic and enhanced I/M programs has largely 

disappeared with the introduction and widespread use of OBD-based testing. And lastly, given 

the degree to which the attainment demonstration will be driven by emission reductions derived 

from I/M or an equally effective alternative, it is reasonable and cost effective to allow states to 

coordinate these two planning requirements. 

11. Oppose implementation of additional I/M programs 

Comment: Commenter (0152) stated, the EPA should consider the elimination of the 

requirement to implement any additional I/M programs. The Commenter added that, although 

this may be a CAA mandate, the EPA has exhibited flexibility in the past to modify the CAA 
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requirements. The EPA appears to acknowledge the practical difficulties with the 

implementation of new vehicle I/M programs. As the older vehicles are removed from the fleet, 

the newer, cleaner, more reliable replacement vehicles emit less and I/M programs become less 

effective in reducing overall emissions. Although the EPA did provide some “out of the box” 

examples of different program options, the fiscal reality makes those concepts impractical. 

(0152)

Response: While the EPA believes that there is flexibility in the I/M rule for allowing equivalent 

mobile source control-based reductions in lieu of traditional I/M, we do not believe we have the 

flexibility to waive the requirement that areas covered by the Act’s I/M requirements reduce 

emissions from mobile sources equal to or greater than the amount they would be reduced if an 

I/M program meeting the applicable performance standard were adopted. 

F. How does transportation conformity apply to the 2008 ozone NAAQS?

1. Requirements for VOC motor vehicle emissions budgets

Comment: The Commenter stated that, for areas where reductions in VOC ozone precursors are 

shown to have minimal effects on ozone air quality, the EPA should remove requirements for 

VOC transportation conformity motor vehicle emissions budgets, including any budget updates 

required for new emissions models. (0130)

Response: The existing transportation conformity regulation already addresses the general 

situation raised by this Commenter. Under 40 CFR 93.109(f), if an ozone nonattainment or 

maintenance area’s SIP can demonstrate that regional VOC motor vehicle emissions are 

insignificant, the area would not be required to establish VOC motor vehicle emissions budgets 

for conformity purposes, and the area would not have to do a regional emissions analysis for 

VOCs. The criteria in this provision for determining insignificance for conformity purposes were 

not the subject of this rulemaking and as such no changes are being made to those criteria. 

2. Elimination of conformity requirements 

Comment: The EPA received two comments on the revocation of transportation conformity 

requirements for the 1997 ozone NAAQS. One Commenter (0172) supported the EPA’s proposal 

that transportation conformity would no longer apply for the 1997 ozone NAAQS once that 

standard is revoked, which was effective July 20, 2013, 1, year after the effective date of 

designations. Another Commenter (0180) stated, the EPA’s proposed revocation of these 

conformity requirements is not consistent with the CAA. 

Response: The D.C. Circuit has held that the CAA did not authorize the EPA to revoke the 1997 

ozone NAAQS for transportation conformity purposes only. NRDC v. EPA, F.3d . 2014 WL 

7269521 (D.C. Cir. 2014). 

Comment: The Commenter stated that, the EPA properly acknowledges that the Act mandates 

that transportation and general conformity requirements apply to all ozone nonattainment or 
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maintenance areas. The Commenter also states that, the EPA further proposes to leave those 

designations for the 1997 NAAQS in place. (0180)

Response: The EPA agrees with the Commenter that, both transportation and general conformity 

apply in all ozone nonattainment and maintenance areas. However, the EPA disagrees with the 

Commenter’s conclusion that the EPA has proposed to retain the designations for the 1997 ozone 

NAAQS. The EPA is today revoking the 1997 ozone NAAQS for all purposes and establishing

anti-backsliding requirements for the revoked standard. The June 6, 2013, NPRM, which 

addresses revocation of the 1997 ozone NAAQS and appropriate anti-backsliding measures for 

all purposes, very clearly states the EPA’s intention with regard to the fate of the designations for 

the 1997 ozone NAAQS:

After revocation of the 1997 standard, the designations for that standard are no longer in 

effect, and the sole designations that remain in effect are those for the 2008 ozone 

NAAQS. However, the EPA is retaining the listing of the designations of areas for the 

revoked 1997 ozone NAAQS in 40 CFR part 81, for the sole purpose of identifying the 

anti-backsliding requirements that may apply to the areas as a result of these designations 

at the time of revocation. Accordingly, such references to historical designations for the 

revoked standard should not be viewed as current designations under CAA section 107. 

(78 FR 34214)

Therefore, after the revocation of the 1997 NAAQS is effective, the EPA will publish a list of 

former designations and classifications for informational purposes in 40 CFR part 81 in order to 

assist state and local agencies and other interested parties in determining the anti-backsliding 

requirements for a given area. At that time, the only applicable designation will be the 

designation for the 2008 ozone NAAQS, the transportation and general conformity requirement 

will apply only for that ozone NAAQS. 

Comment: The Commenter noted that, since the EPA’s June 6, 2013, NPR proposed to revoke 

the 1997 ozone NAAQS for all purposes, that revocation would include transportation 

conformity if the EPA received an adverse decision in the on-going litigation on the revocation 

of the 1997 ozone NAAQS for transportation conformity purposes. Therefore, the Commenter 

asserts that, the NPRM proposes to revoke both the transportation and general conformity 

requirements for the 1997 ozone NAAQS, and that, its comments apply to both types of 

conformity. (0180)

Response: The Commenter is correct and because the D.C. Circuit vacated the EPA’s partial 

revocation of the 1997 ozone NAAQS, today’s rulemaking revokes the 1997 ozone NAAQS for 

all purposes, including both transportation and general conformity purposes.

Comment: The Commenter opines that Congress specified exactly when areas would shed 

conformity requirements, which is after a nonattainment area is redesignated to attainment and it 

completes a 20-year maintenance period. The Commenter believes that, by eliminating the 

conformity requirements before areas complete this process, the EPA contravenes the Act. 
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(0180)

Response: The EPA disagrees with the comment. While the obligation to determine conformity 

for a NAAQS ends after an area is redesignated to attainment and has completed its second 10 

year maintenance period, this is not the only way an area’s conformity obligation could end. 

Clearly, the EPA has revoked the 1-hour ozone NAAQS and areas where that NAAQS has been 

revoked have stopped demonstrating conformity for that NAAQS. The DC Circuit Court in the 

South Coast decision upheld the EPA’s ability to revoke a prior NAAQS as long as appropriate 

anti-backsliding measures are required. (South Coast Air Quality Management District v. EPA, 

472 F.3d 882 (D.C. Cir. 2006)) 

Comment: The commenter opines that even if the EPA could waive the conformity 

requirements by revoking the 1997 NAAQS, it would have to keep them in effect as antibacksliding protections because conformity must apply in nonattainment and maintenance areas; 

therefore, the EPA’s approach results in backsliding because it removes controls that would 

otherwise apply. The Commenter also offers that, Congress crafted the conformity requirements 

to prevent activities from causing or contributing to new violations of any NAAQS or from 

worsening existing violations of any NAAQS. Thus, according to the commenter, conformity 

determinations for the 1997 ozone NAAQS are “[s]omething designed to constrain ozone 

levels,” making them “controls” that must be retained when strengthening a standard, and 

therefore, the EPA cannot do away with them. (0180)

Response: The EPA disagrees with the Commenter and does not understand how it could on one 

hand waive conformity requirements for the 1997 ozone NAAQS through revocation, but on the 

other hand still require conformity determinations for the 1997 ozone NAAQS as an antibacksliding measure. Further, the EPA’s interpretation has been upheld by the D.C. Circuit in a 

similar context, in which the court stated that, conformity determinations are not required as antibacksliding measures for the NAAQS that is revoked. Instead, any existing budgets from a 

revoked NAAQS serve as the test of conformity for an applicable NAAQS of that same 

pollutant, until budgets are established for that applicable NAAQS. Therefore, while conformity 

for the 1997 ozone NAAQS no longer applies, the 1997 ozone NAAQS budgets apply for 2008 

ozone NAAQS conformity until the area has budgets for the 2008 ozone NAAQS. 

The EPA has concluded that the anti-backsliding requirements that apply to the transition from 

the 1997 8-hour ozone NAAQS to the 2008 8-hour ozone NAAQS for conformity purposes are 

well established in the CAA, the transportation conformity rule and recent court decisions. 

(CAA section 176(c)(1), 40 CFR 93.109(c)(2), South Coast Air Quality Management District v. 

EPA, 472 F.3d 882 (D.C. Cir. 2006) and Environmental Defense v. EPA, 467 F3.d at 1329) 

Specifically, areas that are designated nonattainment for the 2008 ozone NAAQS are required to 

demonstrate conformity for that NAAQS using adequate or approved motor vehicle emissions 

budgets for the 2008 ozone NAAQS. Before such budgets are available, areas would use 

adequate or approved budgets for another ozone NAAQS: budgets for the 1997 8-hour ozone 

NAAQS or, if not available, budgets for the 1-hour ozone NAAQS. If no such budgets exist the 

area would demonstrate conformity using the transportation conformity rule’s interim emissions 

tests as they apply to the particular area. (40 CFR 93.109(c)(3) and 40 CFR 93.119(b)) The DC 
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Circuit Court concluded, as is relevant here, that “1-hour conformity [motor vehicle] emissions 

budgets constitute ‘controls’ under section 172(e),” and thus had to be retained to prevent 

backsliding (South Coast Air Quality Management District v. EPA, 472 F.3d 882 (D.C. Cir. 

2006)) In a subsequent ruling denying petitions for rehearing, the Court clarified that this 

“reference to conformity determinations speaks only to the use of 1-hour motor vehicle 

emissions budgets as part of 8-hour conformity determinations until 8-hour motor vehicle 

emissions budgets are available.” Further the court clarified that conformity determinations for 

the 1-hour ozone NAAQS are not required to fulfill anti-backsliding requirements for the 1-hour 

ozone NAAQS. (South Coast Air Quality Mgt. Dist. v. EPA, 489 F.3d 1245, 1248 (D.C. Cir. 

2007)) The Court reached the conclusion that it was not necessary to continue to demonstrate 

conformity for the 1-hour ozone NAAQS after revocation in response to a joint request for 

clarification made by the EPA and the environmental petitioners after the court’s issuance of its 

2006 opinion in that litigation. Id. (granting “joint request by the EPA and Environmental 

Petitioners”) clearly, the DC Circuit Court has already reached a conclusion, which was 

supported by environmental Petitioners, that conformity determinations are not required to 

prevent backsliding in nonattainment or maintenance areas for a NAAQS that has been revoked.

Comment: The Commenter believes that, the EPA has “contravened the statutory mandate” by 

eliminating the transportation conformity requirement in areas that are maintenance or 

nonattainment for the 1997 NAAQS, but attainment for the 2008. The Commenter points out 

that, although some nonattainment and maintenance areas for the 1997 ozone NAAQS have been 

designated attainment for the 2008 ozone NAAQS, conformity requirements remain important 

pollution controls in those areas. The Commenter argues that, to satisfy the conformity 

requirement, an action must not cause or contribute to any new violation, or worsen any existing 

violation, “of any standard in any area” (commenter’s emphasis). Thus, the commenter believes 

that requiring conformity in these 2008 ozone NAAQS attainment areas would also protect 

against violations of the 2008 ozone standard, and the EPA should not revoke the 1997 ozone 

NAAQS because it removes the conformity requirement for these areas without providing antibacksliding protections. In the commenter’s view, this is harmful for implementing the 2008 

standard in areas that have historically had ozone problems. (0180)

The Commenter also notes that, several areas that were nonattainment or maintenance for the 

1997 ozone NAAQS but attainment for the 2008 ozone NAAQS in 2012 are either violating the 

2008 ozone NAAQS or are close to violating that NAAQS based on more recent data. The 

commenter opines that retaining the conformity requirement would provide needed protection 

against dangerous ozone levels. (0180)

Another Commenter stated that, the EPA should act quickly under CAA section 107(d)(3) to 

make sure all areas violating the 2008 NAAQS are properly designated as nonattainment and 

thus properly subject to transportation conformity requirements for that NAAQS. (0177)

Response: The commenter is correct that some areas that were nonattainment or maintenance for 

the 1997 ozone NAAQS were designated attainment for the more health protective 2008 ozone 

NAAQS. These areas all had ozone design values of 75 ppb or less based on 2008-2010 data at 

the time that the designations were made in 2012. Therefore, these areas were attaining the 1997 
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ozone NAAQS by a wide margin since an area would need a design value of 0.085 ppm (85 ppb) 

or greater to be violating the 1997 ozone NAAQS. 

As noted elsewhere in the record for today’s rulemaking, the D.C. Circuit vacated the EPA’s 

revocation of the 1997 ozone NAAQS for transportation conformity only. In doing so, the Court 

recognized that it had previously upheld the EPA’s authority to revoke a standard for all 

purposes, provided that it introduces anti-backsliding measures, as the EPA is doing in today’s 

rule. See NRDC, 2004 WL 7269521. (South Coast Air Quality Management District v. EPA, 472 

F.3d 882 (D.C. Cir. 2006)) upholding revocation of 1-hour standard so long as adequate antibacksliding measures are provided. 

With regard to requiring conformity to the 1997 ozone NAAQS, the commenter attempts to 

make an argument that areas should be required to determine conformity to a revoked NAAQS 

because the CAA section 176(c)(1)(B) refers to “any standard in any area,” including the 2008 

standard in areas that are attaining it. The EPA disagrees with this new interpretation because it 

is inconsistent with other provisions of section 176(c) and with the South Coast decision. First, 

the CAA section 176(c)(5) clearly limits the applicability of conformity requirements to areas 

that are designated nonattainment or maintenance for a given NAAQS. The commenter’s 

interpretation would expand the scope of the conformity requirement to include attainment areas, 

when the plain language of section 176(c)(5) states that the conformity requirement applies “only 

in” nonattainment and maintenance areas. Additionally, as explained above, the D.C. Circuit 

Court ruled in the South Coast decision that the anti-backsliding requirement that applies for 

transportation conformity is that nonattainment areas for the new NAAQS must use approved or 

adequate motor vehicle emissions budgets for the prior NAAQS in transportation conformity 

determinations until the area has approved or adequate budgets for the new NAAQS. The DC 

Circuit Court further held, in response to a joint request for clarification filed by the EPA and 

environmental groups, that conformity determinations were not required for the prior NAAQS 

after it was revoked. (South Coast Air Quality Mgt. Dist. v. EPA, 489 F.3d 1245, 1248 (D.C. Cir. 

2007)) Implementing transportation conformity requirements in ozone areas by requiring 

transportation conformity determinations in nonattainment and maintenance areas for the 2008 

ozone NAAQS, using approved or adequate motor vehicle emissions budgets for the 1997 ozone 

NAAQS until an area has emissions budgets for the 2008 ozone NAAQS and no longer requiring 

transportation conformity determinations for the 1997 ozone NAAQS after the effective date of 

that revocation for all purposes is completely consistent with the CAA requirements, 

transportation conformity regulations and relevant D.C, Circuit Court decisions.

The Commenter is also correct that, some of the 1997 ozone NAAQS nonattainment or 

maintenance areas that were designated attainment for the 2008 ozone NAAQS are now 

violating this NAAQS. In today’s final rule the EPA is finalizing anti-backsliding measures that 

apply to the types of areas that the commenter is concerned about. Those anti-backsliding 

measures are designed to prevent the areas from slipping back into nonattainment of the 1997 

ozone NAAQS. Maintenance areas for the 1997 ozone NAAQS are required to implement their 

approved maintenance plans and nonattainment areas are required to implement their approved 

SIPs for the 1997 ozone NAAQS. These SIPs could only be revised if the revision meets the 

anti-backsliding requirements of the CAA sections 110(l) and 193. 
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Areas designated attainment for the 2008 ozone NAAQS still have an incentive to monitor the 

growth of emissions from the transportation sector, because an area that violates the 2008 8-hour 

NAAQS could be redesignated to nonattainment under the EPA’s discretionary authority to 

quickly redesignate areas. 

Commenter (0177) stated that, the EPA should act quickly under the CAA section 107(d)(3) to 

make sure all areas violating the 2008 NAAQS are properly designated as nonattainment. The 

EPA has carefully evaluated the request by the commenter that the EPA should redesignate as 

nonattainment the counties designated as attainment with 2012 design values violating the 2008 

ozone NAAQS. The EPA also obtained information from the respective states with the 

attainment areas violating based on 2012 design values. The EPA is using the discretion afforded 

to the Administrator under the CAA. If violations of the ozone NAAQS occur, the EPA would 

consider the factors in the CAA section 107(d)(3)(A), which include “air quality data, planning 

and control considerations, or any other air quality-related considerations the Administrator 

deems appropriate.” To the extent an area is actively implementing control measures and 

programs, the EPA may allow time to determine whether such measures and programs bring the 

area back into attainment. As an initial matter, 22 areas with violations based on 2012 design 

values are again attaining the ozone NAAQS based on 2013 design values. As to those areas that 

remain in violation of the 2008 ozone NAAQS, the EPA believes it is appropriate to allow time 

for affected states to assess the new violations and to consider appropriate measures to address 

the air quality problems. The EPA expects that reductions of NOx and VOC emissions from 

existing federal measures and state-led efforts will assist these areas in attaining the 2008 ozone 

NAAQS. For any such redesignated area, conformity would then apply 1 year after the effective 

date of that nonattainment designation.

3. Comment beyond the scope of the rulemaking

Comment: Commenter (0164) recommended further clarification be provided on the 

implications of aspects of the transportation conformity program not addressed by this 

rulemaking. 

Response: These comments are outside the scope of today’s rulemaking, which does not propose 

changes in the transportation conformity regulation. 

G. What requirements for general conformity apply to the 2008 ozone NAAQS? 

1. Emission budgets for General Conformity should not be mandated

Comment: Commenter (0152) does not believe this should be mandated and should be at the 

state's discretion as it is a resource burden that may not be necessary in some states with very 

few projects subject to General Conformity. Commenter (0159) supported the EPA’s 

recommendation that state and local air quality agencies work with federal agencies with major 

facilities that are subject to the General Conformity Regulations to establish an emission budget 

for those facilities in order to facilitate future conformity determinations, noting that state and 
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federal agencies should work together in a cooperative manner to achieve establish emissions 

budgets that will ensure that transportation plans, TIPs and federally supported highway and 

transit projects are consistent with the applicable SIP.

Response: The EPA has not mandated facility emission budgets in this proposal or in its 

regulations for general conformity. Facility emission budgets are voluntary when a facility and a 

state believe it is beneficial to develop one.

2. Support proposal to not make revisions to general conformity regulations

Comment: Commenter (0159) supported the proposal to not make revisions to the General 

Conformity Regulations in this SIP Requirements Rule, agreeing with the EPA that states with 

approved General Conformity SIPs should not need to revise those SIPs, unless they need to do 

so to ensure the existing regulations apply in the appropriate newly designated areas.

Response: The EPA appreciates the commenter’s support and concurs with the commenter’s 

statement.

H. What are the requirements for contingency measures in the event of failure to meet a 

milestone or to attain?

1. 1 year’s worth of progress

Comment: Allow approximately one year’s worth of emissions reductions based on air 

quality improvements

Commenters (0139, 0150, 0155 and 0160) requested, the EPA to use the term “approximately 1 

year’s worth” to allow a certain amount of flexibility. Commenters (0139 and 0150) stated, 

flexibility may be needed for cases where the region either does not need a full year’s worth of 

reductions or would find it impossible to find a measure that produces a full year’s worth of 

reductions above and beyond what is required to attain. Commenter (0160) appreciated the 

flexibility the EPA exercised in approving the South Coast's PM2.5 contingency measures, and a 

similar approach should be possible for ozone contingency measures. Commenter (0139) stated 

that, a strict requirement for a full 1 year’s worth of reductions could have the perverse effect of 

delaying attainment. This is because if an area could attain in 5 years, its reduction line is quite 

steep, and 1 year’s worth of reductions could be a significant amount, and the state may not be 

able to define a measure to obtain sufficient reductions above and beyond what is required to 

attain. On the other hand, if the state takes 8 years to attain, its reduction line will be less steep, 

and 1 year’s worth of reductions will be smaller. Thus, the state may be forced to delay 

attainment in order to meet the requirement for 1 year’s worth of reductions as a contingency 

measure. 

Commenters (0139 and 0150) suggested that, similar to RFP, the EPA should allow an air 

quality improvement measurement in measuring 1 year’s worth of progress for contingency 

measures. These Commenters stated that, in the case of contingency measures, Congress did not 

specify any particular method of measuring required progress, either tonnage reductions or air 
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quality improvement. Therefore, the EPA’s interpretation must be upheld if it reflects a 

reasonable accommodation of the policy interests involved in interpreting the Act. Chevron 

U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 843-45 (1984). The 

Commenters argued that, the EPA has already accepted the concept that air quality 

improvements may be taken into consideration for purposes of evaluating the level of emission 

reductions needed to meet the contingency measure requirements. “Approval and Promulgation 

of Implementation Plans; California; South Coast; Contingency Measures for 1997 PM2.5

Standards”; 78 FR 37741, 37748 (June 24, 2013). The EPA allowed South Coast to have less 

than 1-year’s worth of emission reductions in its contingency measures based on the degree of 

air quality improvement shown by the area. It is a small step from there to conclude that if any 

area can demonstrate that its proposed contingency measures will produce 1-year’s worth of air 

quality improvements, that this can be accepted in lieu of 1 year’s worth of emission reductions. 

Response: The EPA appreciates the Commenters’ suggestions to allow “approximately” 1 year’s 

worth of reductions in area’s that may not need a full year’s worth of reductions or may find it 

impossible to find a measure that produces a full year’s worth of reductions above what is 

required to attain. The contingency measures must be put in place if the area fails to make RFP 

or to attain. The “Guidance for Growth Factors, Projections and Control Strategies for the 15 

Percent Rate-of-Progress Plans” (March 1993), Section 9.0, Contingency Measures, (pages 81-

97), cites the April 16, 1992, General Preamble section III.A.3.c (57 FR 13498, at 13510 -

13512) as the source of the EPA’s interpretation that 3 percent of the RFP baseline is the 

minimum contingency measure requirement. But the contingency measures would provide for 

reductions in emissions rather than measured ozone concentrations, and the EPA did not propose 

to alter this guidance or specifically allow an alternative air quality improvement-based 

approach. 

The implementation of PM2.5 NAAQS is governed by statutory and regulatory requirements that 

are separate from and not identical to requirements for ozone NAAQS implementation and

provide flexibility for states to consider the degree of air quality improvement that may be 

needed in developing RFP plans and contingency measures. Thus, in a recent action,20 the EPA 

has approved a state to adopt into its PM2.5 SIP, contingency measure emissions reductions based 

on the degree of air quality improvements shown by the area. However, the CAA provisions for 

ozone NAAQS implementation provide for emission reductions of ozone precursors, VOC and 

NOx, and do not explicitly authorize using measurements of ozone concentrations for fulfilling 

SIP emission reductions requirements for RFP and its associated contingency measures.

2. Reliance on already-adopted rules

Comment: Commenter (0150) requested that the EPA make it clear that a state may rely on 

already-adopted rules and regulations. The Commenter stated that, in proposing to approve the 

 

20 “Approval and Promulgation of Implementation Plans; California; South Coast; Contingency 

Measures for 1997 PM2.5 Standards”; 78 FR 37741, 37748 (June 24, 2013).
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South Coast PM2.5 contingency measures, the EPA recently made it clear that a state may rely on 

already-adopted rules and regulations, whether federal, state or local, provided they result in 

emission reductions that are surplus to what is needed for RFP or attainment. The EPA noted that 

it had approved numerous SIPs under this interpretation. 78 FR 37741, 37744 col. 1. The EPA 

explained that this approach has been upheld by the courts. LEAN v. EPA, 382 F.3d 575 (5th Cir. 

2004). We request that the EPA repeat this analysis in the present implementation rule, so that 

the principle will be known to all parties and to provide a ready reference for the principle, 

without having to rely on individual SIP approval actions. Commenters (0159 and 0179) agreed 

that, federal measures that provide ongoing reductions into the future can be used as contingency 

measures, where appropriate. 

Response: In regards of maintaining ongoing provisions where federal measures can be used as 

contingency measures, the EPA has a long-standing practice of allowing federal measures to be 

used as contingency measures as long as they provide emissions reductions in the relevant years 

in excess of those needed for attainment or RFP. The EPA has approved the use of federal 

measures to meet contingency measure requirements in several EPA actions approving 1-hour 

and 8-hour ozone SIPs. (62 FR 15844, April 3, 1997), (62 FR 66279, December 18, 1997), (66 

FR 30811, June 8, 2001), (66 FR 586 and 66 FR 634, January 3, 2001) (74 FR 1903, January 14, 

2009). The EPA is continuing to allow areas to use future reductions from promulgated federal 

measures as contingency measures for the 2008 ozone NAAQS final rule, consistent with our 

practice for both the 1-hour and 1997 ozone NAAQS.

Comment: Fleet turnover emission budgets

One Commenter (0132) stated that, additional “fleet turnover” motor vehicle emissions budgets 

(MVEB) for the year after the attainment year are unnecessary because fleet turnover is based on 

federal vehicle emission standards already in place, and the EPA has not indicated that those 

standards will be unavailable in the future. Further, the proposal does not address the 

implications of a 2019 contingency MVEB on conformity. It would be inappropriate and unduly 

restrictive to set a contingency MVEB and then, in effect, require areas to base conformity 

analyses on a contingency MVEB. 

A second commenter (0169) MVEBs language on page 34199 is vague and requested that the 

EPA revise the current preamble language. 

Response: One Commenter opined that, the motor vehicle emissions budgets should be 

unnecessary because the EPA has not indicated that the vehicle emissions standards would not be 

available in the future. It was not the EPA’s intention to imply that the concern was with whether 

or not the national emission standards for new vehicles would remain in effect. The EPA 

recommended that these budgets be established to ensure that on-road emissions remain at or 

below the level established by the contingency measure. This level would be equal to the level of 

emissions in the attainment year minus the amount of emissions reductions attributable to the 

fleet turnover contingency measure. There are a number of reasons that emissions could increase 

such as an unanticipated increase in vehicle miles traveled or in the number of vehicle trips in the 

area. Demonstrating conformity to these budgets in the event that the contingency measure is 

triggered it would ensure that emissions were reduced at least to the level that the contingency 
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measure had anticipated. The EPA is not requiring states to establish these budgets. The EPA is 

recommending that states establish such budgets. The EPA agrees that, areas should not be 

required to demonstrate conformity to these budgets until such time that the contingency 

measure is triggered. Therefore, areas would only have to demonstrate conformity to these 

budgets in the event that the area misses its attainment date and the fleet turnover contingency 

measure is triggered. 

The second Commenter suggested that, the discussion of this issue in the preamble to the NPRM 

is vague and should be revised. The commenter did not provide any specific information on the 

clarifications that they believe are needed. The EPA made revisions to the preamble in the final 

rule. If the commenter continues to have questions after the rule is finalized, they should contact 

their EPA Regional Office. 

3. Flexibility to use NOx or VOC measures

Comment: Support NOx only flexibility for measuring contingency measures

Commenters (0130, 0139, 0143, 0150, 0155, 0157, 0159, 0163 and 0179) generally supported 

the proposal to modify contingency measures regarding emission reductions from VOC. 

Commenters (0130 and 0143) stated that, science shows that NOx reductions are much more 

effective than VOC reductions for reducing ground-level ozone concentrations in much of the 

eastern U.S.; therefore, allowing states the flexibility to reduce the full 3 percent as NOx for 

contingencies makes good sense. Commenter (0143) stated that, reducing NOx emissions appears 

to have at least the same and possibly a larger, effect on reducing ozone levels as reducing an 

equal amount of VOC emissions. Recent studies indicate that NOx, reductions have great 

potential to reduce the number of ozone exceedances where a NOx-limited condition exists. In 

Pennsylvania, with the actual and pending shutdown of certain coal-fired power plants, NOxlimited conditions will become more common. A NOx for VOC substitution, which would rely 

on NOx reductions in place of VOC reductions, should lower the number of ozone exceedances 

in ozone nonattainment areas of the Commonwealth. 

Commenters (0139 and 0150) stated, a flexible and common sense approach is needed in 

interpreting the contingency measure requirement, and for that reason, we do support the EPA’s 

proposal to change its guidance such that there would no longer be a minimum requirement for 

VOC reductions; instead the area’s entire contingency measure content could consist of NOx

reductions (78 FR 34199 col. 1). Commenters (0155, 0157 and 0163) stated that, for Moderate 

and above areas that have completed the initial 15 percent VOC reduction required by the CAA 

section 182(b)(1)(A)(i), the 3 percent emissions reductions of the contingency measures may be 

based entirely on NOx controls if that is what the state's analyses have demonstrated would be 

most effective in bringing the area into attainment; there is no minimum VOC requirement. 

Commenter (0179) took the position that only measures that are expected to offer a worthwhile 

reduction in ozone (i.e., NOx controls) should be considered for contingency measures. 

Response: The EPA appreciates the support and is finalizing requirements that contingency 

measures must be submitted for approval into the SIP as required by the CAA and must provide 
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for the implementation of specific measures without any further rulemaking action if the area 

fails to attain or meet any applicable milestone. Regarding content of the 1-year’s worth of 

emissions covered by the contingency measures, the EPA is finalizing its proposal to allow the 3 

percent emissions reductions of the contingency measures to be based entirely on NOx controls if 

the area can demonstrate it has achieved the initial 15 percent ROP VOC reduction required by 

the CAA section 182(b)(1)(A)(i) and that the state’s analyses determine that NOx substitution 

would be most effective in bringing the area into attainment.

4. Extreme nonattainment areas

Comment: Support the proposal

Commenters (0139, 0149, 0150, 0160 and 0166) supported use of section 182(e)(5) measures for 

contingency measures. Commenter (0139) supported the EPA’s acknowledgement that, 

contingency measures as previously implemented may not make sense in Extreme nonattainment 

areas and that allowing some flexibility and creativity for contingency approaches is important 

for areas that have implemented all reasonable and feasible measures under their regulatory 

control. Commenter (0160) stated, this approach reflects the need for Extreme areas to adopt all 

feasible measures, while recognizing that over time additional new measures will be possible as 

technology advances. Commenter (0166) stated that, it would in fact be unreasonable to expect a 

state that is already adopting all feasible controls to adopt additional contingency measures; once 

a state has adopted all measures that are feasible, by definition nothing more can be 

accomplished.

Commenter (0149) stated that, developing and adopting contingency measures in regulatory 

form (pursuant to CAA sections 172(c)(9) and 182(c)[9]) for an “Extreme” nonattainment area 

that qualifies for the CAA section 182(e)(5) is not practical. Commenter (0149) stated that such a 

nonattainment area has already included all reasonable control measures in its SIP to meet 

RACM and RFP requirements and is allowed to rely on section 182(e)(5)measures (which are 

themselves not fully developed) for its attainment demonstration. 

Commenter (0150) stated that, unlike other contingency measures, these measures are not 

required to be in regulatory form at the time the attainment demonstration is submitted; instead, 

the Extreme area commits to submit those measures by 3 years before the time the reductions are 

needed. CAA § 182(e)(5); 42 U.S.C. § 7511a(e)(5). Commenter (0150) agreed that an Extreme 

area should not be forced to rely on infeasible or draconian measures to meet the contingency 

requirements. Commenter (0150) cited Long Island Care at Home, Ltd. v. Coke, 551 U.S. 158, 

170 (2007) and stated that, similarly, the specific§ 182(e)(5) contingency measures designed 

specifically to suit the needs of an Extreme ozone area should be considered to control over the 

more general requirements for ozone. 

Commenter (0150) stated, the EPA may rely on the doctrine of unreasonable results and absurd 

consequences to support this interpretation and cited two court cases. Commenter (0150) stated 

since the EPA has already recognized that requiring the "normal" contingency measures for an 
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Extreme area would be unreasonable (78 FR 34199 col. 2), such an interpretation should be 

rejected. 

Response: We appreciate the supportive comments. We recognize that all areas must meet the 

contingency plan requirements of sections 172(c)(9) and 182(c)(9). We agree that the CAA 

section 182(e)(5) provides the agency discretion to approve an Extreme area attainment plan that 

relies, in part, on the future development of new control technologies or improvements of 

existing control technologies. This authority can be exercised as long as the state has 

demonstrated that: all reasonably available control measures, including RACT, have been 

included in the plan; the area’s RFP demonstration during the first 10 years after designation 

does not rely on anticipated future technologies; and the state has submitted enforceable 

commitments to develop and adopt contingency measures in the event that anticipated future 

technologies do not achieve planned reductions. 

Comment: Do not support proposal where “reasonably available” control measure are 

appropriate for determining when to exercise discretion provided by section 182(e)(5)

Commenter (0180) stated, the EPA has no authority to waive the plain statutory requirements of

sections 172(c)(9) and 182(c)(9). Commenter (0180) stated that, because section 172(c)(1) 

requires nonattainment plans for all areas provide for the implementation of all RACM, Congress 

assumed that all nonattainment areas–not just Extreme areas – would implement all reasonable 

measures. Commenter (0180) stated that, contingency measures are not limited to measures 

deemed “reasonable” because such “reasonable” measures must already be required and 

implemented in all nonattainment areas. Commenter (0180) stated the flaw in the EPA’s 

description of the situation facing Extreme ozone nonattainment areas is that once all 

“reasonable” measures are adopted to meet RACM and RFP, additional measures are 

“unreasonable” and “draconian.” Commenter (0180) stated the CAA contains several 

requirements with levels of control that are more stringent than RACM, including LAER, 

BACM and 7513(e) (requiring MSM). Commenter (0180) stated, there is no basis for suggesting 

that Congress did not contemplate areas adopting controls that go above and beyond RACM or 

that such controls could be ruled out as “unreasonable.” Commenter (0180) further pointed out 

that, ozone nonattainment areas must adopt whatever controls are “necessary or appropriate to 

provide for attainment of such standard in such area by the applicable attainment date specified 

in this part.” 

Commenter (0180) stated that, if an Extreme nonattainment area seeks to rely on a “black box” it 

should be required to demonstrate that all feasible control measures have been adopted, 

regardless of whether those control measures can be demonstrated to advance attainment by a 

year. Commenter (0180) stated, the EPA should also clarify that RACM is the minimum level of 

control required to be demonstrated in these nonattainment plans. 

Response: The EPA believes that both its long-standing interpretation of RACM and its focus on 

whether control measures are “reasonably available” provide an appropriate framework for 

determining when to exercise the discretion provided by section 182(e)(5). As noted in the 

proposal, the determination of whether a SIP contains all RACM requires an area-specific 

analysis establishing that there are no additional economically and technically feasible control 
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measures (alone or cumulatively) that will advance the attainment date by 1 year. This requires 

close review of any measure that a commenter identifies as reasonably available for 

implementation in the area in light of local circumstances and of measures being implemented in 

other states. 78 FR 34187, at 34194 (June 6, 2013). This interpretation of RACM has been 

upheld as reasonable (e.g. Sierra Club v. EPA, 294 F3d 155, 162-163 (D.C. Cir. 2002)). Thus, 

the EPA believes that, it is appropriate to require that an area seeking to rely on the anticipated 

development of new technology demonstrate that its plan includes all control measures that come 

within this definition of “reasonably available.” The EPA does not believe it is necessary for an 

area to demonstrate the use of measures that go beyond that definition in order to meet 

contingency measure requirements. 

5. Innovative measures

Comment: Commenter (0179) supported the integration of innovative measures such as energy 

efficiency programs or renewable energy programs that meet the requirements of the CAA 

section 172(c )(9) and section 182(c)(9) for areas classified as Serious or higher to be used as 

contingency measures. Commenter (0180) agreed that, innovative measures may be allowed if 

they otherwise comply with the requirements for contingency measures; i.e., emission reductions 

must be quantifiable, surplus, permanent and enforceable. 

Response: The EPA appreciates the Commenters support and the EPA will continue to allow 

and encourage implementation of innovative measures such as energy efficiency programs or 

renewable energy programs that may be satisfy the requirements of the CAA section 172(c)(9) 

and 182(c)(9).

I. How do the NSR requirements apply for the 2008 ozone NAAQS?

1. General NSR requirements for the 2008 ozone NAAQS

Comment: Permit programs must help ensure attainment and maintenance

Commenter (0140) encouraged EPA to use this implementation rule to ensure that states make 

changes to their permitting programs that would be necessary to avoid their interference with 

attainment and maintenance of the 2008 ozone NAAQS. The commenter indicated that as 

representatives of an area where elevated ozone levels primarily come from beyond our 

boundaries and are heavily influenced by emissions from rural counties, the CACAC believes 

that this implementation rule should provide more rigorous requirements for state agencies to 

show that their permitting programs do not interfere with attainment and maintenance of the 

ozone standard. This is particularly needed to address the problems from the issuance of broad 

“permits by rule” for smaller sources like oil and gas equipment that, in aggregate, can cause 

very significant ozone impacts if upwind of a nonattainment or near-nonattainment area. In order 

to address permitting for smaller sources, the CACAC recommends that the EPA require that any 

emissions authorized by permit – including permits by rule – be modeled in any future year 

projection, and that all sources holding an authorization be limited to only what emissions are 
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modeled in the attainment demonstration. This would ensure that state agencies institute limits 

on emissions from smaller sources that are consistent with their own modeling assumptions.

Another way that would provide more flexibility would be to set emission authorization limits 

for counties, groups of counties, or an entire AQCR consistent with the modeling assumptions.

More robust requirements are also particularly needed for permitting larger point sources that 

may not cause ozone NAAQS violations through reactions of its own NOX and VOC emissions, 

but which, when added to the ozone and precursors already in the atmosphere, cause violations 

nearby. The CACAC recommends that states require photochemical modeling using either the 

platform EPA uses for its modeling or a platform adopted by the State as part of a SIP 

submission. At a minimum, permit applicants seeking to build a new major source or undertake a 

major modification of an existing source within the same AQCR as an area that is designated 

nonattainment or has a design value within 5% of the NAAQS should have to model their 

permit’s impacts on eight-hour ozone averages at regulatory monitors within the same AQCR, 

and should be limited to an average impact on those monitors of 0.75 ppb or less, and that the 

emissions would not cause a modeled violation in any grid cell where no violation was modeled 

if the source was not included. Provisions could be made to account for model performance 

measurements, adjusting the impacts and values in these grid cells to account for the model’s 

bias. Regardless, photochemical modeling is common enough and inexpensive enough that a 

permit for a major new source should not be granted until photochemical modeling is performed 

that demonstrates that it won’t interfere with attainment or maintenance of the standard, or cause 

a significant deterioration in ozone levels.

Response: The commenter appears primarily concerned about the effect that source growth 

occurring outside of a particular nonattainment area for ozone may have on downwind 

nonattainment areas, and urges that “this implementation rule should provide more rigorous 

requirements for state agencies to show that their permitting programs do not interfere with 

attainment and maintenance of the ozone standard.” As discussed further below, there are several 

provisions in existing EPA regulations that require states to have permitting programs to ensure 

attainment and maintenance of the ozone standard within their boundaries and in neighboring 

states. The EPA believes the commenter’s concerns can primarily be addressed through the 

application of those requirements in individual state plans. Thus, we do not believe additional 

changes to EPA regulations (beyond those in this rulemaking) are needed for this purpose. In a 

separate action, the EPA is considering the extent to which EPA regulations should be revised to 

provide more specific guidelines on the use of photochemical modeling.

To the extent that the commenter is addressing how a specific state with a nonattainment area 

accounts for new source growth in an attainment demonstration, that is best addressed in the 

review of individual state plans. We are not in this action adopting changes to our regulations or 

guidance that uniquely address a specific ozone nonattainment area. We recognize that each 

nonattainment area has unique characteristics and a state should take that into consideration in 

formulating an individual attainment demonstration. 

The commenter provides various recommendations for enhancing the permitting requirements 

for both large and small sources to ensure permit programs do not interfere with attainment and 
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maintenance, including for permits by rule. It is important to note that the EPA did not discuss or 

propose any regulation or policy change for permits by rule in this rulemaking. Such permits are 

typically issued to minor sources pursuant to state minor source permitting programs, which are 

subject to the requirement in 40 CFR 51.160, that permitting authorities be able to prevent any 

construction or modification that would interfere with attainment or maintenance of any 

NAAQS. Accordingly, states are already required to ensure that no sources authorized for 

construction under its minor source program, including a source authorized by a permit by rule, 

regardless of its location relative to a nonattainment area, will interfere with the attainment and 

maintenance of any NAAQS.

With regard to new or modified sources that are located outside the nonattainment area and in 

areas designated as attainment or unclassifiable for the ozone NAAQS, such sources would not 

be subject to nonattainment NSR requirements, which include requirements to apply LAER

control technology and to acquire emissions reductions from existing sources to offset the 

emissions increase that will result from the proposed new or modified major source. Instead, the 

applicable permitting requirements for new major stationary sources and major modifications 

locating in attainment and unclassifiable areas are the Prevention of Significant Deterioration 

(PSD) Program, which are required under Part C of subchapter I of the Clean Air Act.

The PSD program requires that major stationary sources conduct an air quality impact analysis to 

demonstrate that emissions from the construction or operation of the proposed source or project 

will not cause or contribute to a violation of any NAAQS or PSD increment. CAA § 165(a)(3); 

see also, 40 CFR 51.166(k), 40 CFR 52.21(k). Thus, to obtain a PSD permit, a new major 

source or major modification must demonstrate that it will not cause or contribute to a violation 

of any NAAQS. More specifically, consistent with section 165 of the Act, the PSD regulations 

at 40 CFR 52.21(k) and 51.166(k) require a source owner or operator to demonstrate that 

allowable emissions increases from the proposed source or modification in conjunction with 

other source emissions in the area will not cause or contribute to a violation of any NAAQS in 

any air quality control region. In light of these existing requirements, EPA does not agree that the 

changes the commenter recommends for PSD permitting are necessary. Moreover, the EPA 

works closely with states, primarily through its Regional Offices, to ensure that new and 

modified major sources are adequately reviewed to protect the NAAQS. To the extent that the

commenter offers recommendations with regard to the manner in which sources locating near but 

not in nonattainment areas should be analyzed, we are not adopting new procedures into 

regulations or providing new guidance on how the air quality impact analysis should be done. 

With respect to the commenters’ suggestion that the EPA should require the use of 

photochemical modeling to complete the source impact analysis for permitting purposes, the 

EPA’s judgment has been that it was not technically sound to designate specific models that 

must be used to assess the impacts of a single source on ozone concentrations. Thus, EPA does 

not require use of photochemical models to assess the impacts of a single source on ozone 

concentrations. Nevertheless, the EPA recognizes and has explained that sources subject to PSD 

have a statutory and regulatory obligation to conduct a source impact analysis and to demonstrate 

that any proposed emissions increase will not cause or contribute to a violation of any NAAQS. 

To satisfy that requirement, EPA has explained that the particular models or other analytical 
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techniques that should be used is determined on a case-by-case basis. As stated in Section 5.2.1.c 

of the EPA’s “Guideline on Air Quality Models,” (GAQM) codified in Appendix W to 40 CFR 

part 51, the "[c]hoice of methods used to assess the impact of an individual source depends on 

the nature of the source and its emissions." Under GAQM, the appropriate methods are 

determined in consultation with the EPA Regional Office on a case-by-case basis. A modeling 

protocol should be developed and approved by the EPA Regional Office, the state/local agency, 

and the applicant to ensure that the analysis conducted will conform to the recommendations, 

requirements, and principles of Appendix W. 40 C.F.R. Part 51, Appendix W, section 3.2.2. 

The EPA is also engaging in a separate rulemaking process to evaluate whether updates to 

Appendix W are warranted for ozone and is planning to propose a rulemaking in 2015 to consider 

whether to update Appendix W. See Letter from Gina McCarthy, Assistant Administrator, to 

Robert Ukeiley (Jan. 4, 2012), available at

http://www.epa.gov/scram001/10thmodconf/review_material/Sierra_Club_Petition_OAR-11-

002-1093.pdf. To the extent that recent advances in photochemical modeling science suggest that 

it may now be reasonable for the EPA to provide more specific, generally-applicable guidelines 

that identify particular analytical techniques or models that may be used under specific 

circumstances for assessing the impacts of an individual source on ambient ozone 

concentrations, such emerging capabilities could be considered as part of the consultative 

process already in place and are also being considered as part of the ongoing process to evaluate 

potential updates to Appendix W.

With respect to emissions that cross state boundaries, section 110(a)(2)(D)(i) of the Clean Air 

Act requires that State Implementation Plans contain adequate provisions that prohibit “any 

source or other type of emissions activity with the state from emitting any air pollutant in 

amounts which will – . . . (II) interfere with measures required to be included in the applicable 

implementation plan for any other state under part C of this subchapter to prevent significant 

deterioration of air quality or to protect visibility.” EPA has previously promulgated a 

regulation which requires that SIPs contain a preconstruction review program or its equivalent to 

satisfy the requirements of this section of the Act. 40 C.F.R. § 51.165(b). 

Comment: Grandfathering

Commenter (0180) stated that EPA has correctly refused to allow grandfathering of permit 

applications pending at the time of a NAAQS revision, citing section 165(a)(3) of the CAA and 

arguing that the CAA does not authorize such grandfathering. Commenter (0180) also stated the 

Agency must abandon any suggestion that it has any authority under the CAA to exempt 

facilities from the requirements of PSD if EPA or a state or local permitting authority receives a 

permit application prior to the issuance of new or revised NAAQS. In addition to the 

commenter’s interpretation that the CAA prohibits such grandfathering, the commenter claimed 

that to allow for grandfathering of permit applications would be “a reversal of” the EPA’s own 

policy, as contained in a 2010 Memorandum from Stephen D. Page, Director, Office of Air 

Quality Planning & Standards, entitled “Applicability of the Federal Prevention of Significant 

Deterioration Permit Requirements to New and Revised National Ambient Air Quality 

Standards” (April 1, 2010).
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Response: As acknowledged by the commenter, the EPA indicated in footnote 53 of the 

preamble to the proposed rule that we did not propose a PSD grandfathering provision for the 

2008 ozone NAAQS, and we are not promulgating such a provision in this final rule. As 

explained in both the preamble to the final rule and the proposal, in this particular situation, 

because the 2008 ozone NAAQS has been in effect for a considerable time, we have concluded 

that a grandfathering provision is not necessary. Accordingly, these comments relating to EPA’s 

grandfathering authority are outside the scope of this rulemaking. Nevertheless, we disagree with 

the commenter’s position that the EPA lacks statutory authority to exempt pending PSD permit

applications from certain PSD requirements that become applicable while the permit application 

is pending. 

With regard to section 165(a)(3) of the CAA, as well as the implementing PSD regulations, the 

owner or operator of a proposed facility is required, among other things, to demonstrate that 

“emissions from construction or operation of such facility will not cause, or contribute to, air 

pollution in excess of any ... national ambient air quality standard in any air control region.” See 

also 40 CFR 51.166(k), 40 CFR 52.21(k). The EPA has interpreted this requirement to include 

any NAAQS that is in effect as of the date a permit is issued, unless the EPA has issued a 

regulation that grandfathers pending permit applications from the requirement to demonstrate

that the proposed facility does not cause or contribute to a violation of the new or revised 

NAAQS. See, e.g., 73 FR 28321, 28324, 28340 (May 16, 2008); 78 FR 3253 (Jan. 15, 2013); 

Memorandum from Stephen D. Page, Director, Office of Air Quality Planning & Standards, 

“Applicability of the Federal Prevention of Significant Deterioration Permit Requirements to 

New and Revised National Ambient Air Quality Standards” (April 1, 2010). Thus, the EPA 

believes that the commenter’s citation of the 2010 Page Memo does not correctly characterize 

what the EPA said in that memorandum. Nothing in that memo would preclude us from 

adopting a grandfathering provision where we deem one to be appropriate and follow the 

necessary rulemaking process. In fact, the memorandum recognizes that the EPA has previously 

issued regulatory provisions to grandfather PSD sources from new requirements under certain 

circumstances and includes examples of situations in which the EPA has taken such an approach. 

See, e.g., Memorandum from Stephen D. Page, Director, Office of Air Quality Planning & 

Standards, “Applicability of the Federal Prevention of Significant Deterioration Permit 

Requirements to New and Revised National Ambient Air Quality Standards” (April 1, 2010) at 

3.

As the agency has previously stated, and continues to believe, the relevant provisions of the 

CAA provide the agency with the discretion to promulgate regulations to grandfather pending 

PSD permit applications from requirements that become applicable while the applications are 

pending. See 45 FR 52683, August 7, 1980; 52 FR 24672, July 1, 1987; 78 FR 3086, January 15, 

2013. As discussed in more detail in these referenced actions, section 165(a)(3) of the CAA 

requires that a permit applicant demonstrate that its proposed project will not cause or contribute 

to a violation of any NAAQS. At the same time, section 165(c) of the CAA requires that a PSD 

permit be granted or denied within 1 year after the permitting authority determines the 

application for such permit to be complete. In addition, section 301 of the CAA authorizes the 

Administrator “to prescribe such regulations as are necessary to carry out his functions under this 
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chapter.” When read in combination, these three provisions of the CAA provide the EPA with 

the discretion to issue regulations to grandfather pending permit applications from having to 

address a revised NAAQS where necessary to achieve both CAA objectives to protect the 

NAAQS and to avoid delays in processing PSD permit applications.

Moreover, in a recent opinion the U.S. Court of Appeals for the Ninth Circuit recognized the 

EPA’s traditional exercise of grandfathering authority through rulemaking and indicated that this 

approach was consistent with statutory requirement to “enforce whatever regulations are in effect 

at the time the agency makes a final decision” because it involved identifying “an operative date, 

incident to setting the new substantive standard, and the grandfathering of pending permit 

applications was explicitly built into the new regulations.” Sierra Club v. EPA, 762 F.3d 971, 

983 (9th Cir. 2014). Thus, while this court decision vacated the agency’s action to grandfather an 

individual permit application on a case-by-case basis without rulemaking, the EPA does not 

interpret this opinion to limit its authority to grandfather through rulemaking, and rather believes 

that the decision offers support for such authority. This authority includes, in appropriate 

circumstances, discretion to grandfather sources through rulemaking from the requirement to 

address a new or revised NAAQS that takes effect while the permit application is pending in its 

demonstration that the proposed project does not cause or contribute to a violation of any 

NAAQS.

Comment: PSD permitting and modeling

Commenter (0159) supported the EPA's position that the demonstration that a proposed source or 

modification will not cause or contribute to a violation of the 2008 ozone NAAQS does not 

necessarily require permit applicants to perform new air quality modeling. The commenter

believed that the EPA has stated that PSD permit applicants and permitting authorities should 

continue to follow the current practice described in Appendix W to 40 CFR part 51. 78 FR at 

34,200. The commenter supported the EPA's position on this matter, as the current practice 

stated that PSD permit applicants and permitting authorities should consult with the applicable 

EPA regional office to determine the appropriate means of addressing such impacts. The 

commenter also agreed that a spirit of cooperativeness and collaboration between the regulated 

community, the states, and federal government is the best method to achieve attainment with the 

ozone NAAQS. 

On the other hand, commenter (0180) stated that the EPA should require applicants to undertake 

new air quality modeling when seeking a new PSD permit. This commenter stated that the

proposal cites Appendix W to suggest that applications for PSD permits do not “necessarily 

require the permit applicants to perform new air quality modeling.” 78 FR at 34200. The 

commenter believed that the EPA suggested that a “case-by-case” approach devoid of modeling 

could satisfy the requirement that applicants demonstrate that the “proposed source or 

modification will not cause or contribute to a violation of the 2008 ozone NAAQS.” Id. 

However, the commenter believed the requirement that a source undertake modeling is dictated 

by the Act itself, in section 165(e), where the Administrator must “specify with reasonable 

particularity each air quality model or models to be used under specified sets of conditions.” 42 

U.S.C. § 7475(e)(3)(D). Moreover, the statute acknowledges that models may need to be 
146

adjusted, where any model or models “designated . . . may be adjusted upon a determination, 

after notice and opportunity for public hearing . . . that such adjustment is necessary to take into 

account unique terrain or meteorological characteristics of an area potentially affected by 

emissions from a source applying for a permit.” 42 U.S.C. § 7475(e). 

The commenter further believed that the statute does not, however, provide for elimination of the 

modeling requirement, since, as section 165(e) makes clear, the analysis required by the section 

is critical to the execution of section 165(a)’s permitting processes. The commenter further stated 

though certain source-specific factors may vary when undertaking the air quality review 

described by section 165(e), the Act makes clear that modeling is expected with all applications, 

the results of which must then be available to the public for review. The commenter stated that 

failing to require modeling in an application provides a less complete picture of air quality in the 

area. The commenter concluded that, as such, permit applicants may be over- or under-correcting 

their emissions, and it is the public that pays the price. The commenter suggested that the EPA 

should require applicants to undertake new air quality modeling when seeking a new PSD 

permit. 

The commenter implied that by the time the EPA finalizes this rulemaking, it will have been 

over two years since EPA granted Sierra Club’s July 28, 2010 petition to designate air quality 

models for ozone for use by all major sources applying for a PSD permit. The commenter further 

pointed out that since that time, the EPA has held its Tenth Conference on Air quality Modeling 

and its 2012 RSL Modelers’ Workshop where this topic was addressed. The commenter 

suggested that it is now time for the EPA to stop delaying and, in this rulemaking, designate a 

model or models for use in analyzing ozone impacts for PSD permits. The commenter believed 

this is especially critical because there are many, many areas of the country where the ambient 

levels of ozone are at or above the 2008 ozone NAAQS but are nevertheless, designated 

attainment so that PSD applies. The commenter considered that the EPA’s concern that ozone 

modeling is too expensive to require of PSD applicants is factually incorrect and legally 

irrelevant. Furthermore, as the commenter noted above, even once the EPA designates a model 

or models, applicable regulations provide a mechanism for adjusting the designated model if that 

is truly needed. 

Response: We agree with the comment supporting our position that air quality modeling is not 

necessarily required as part of every ambient impact analysis for ozone required by the CAA’s 

PSD requirements. On the other hand, we disagree with the comment asserting that section 

165(e) of the CAA compels each PSD applicant to undertake new air quality modeling when 

seeking a new PSD permit. Section 165(e)(3)(D), which the comment cites, requires in relevant 

part that the Administrator adopt regulations specifying “with reasonable particularity each air 

quality model or models to be used under specified sets of conditions.” To carry out these 

requirements, in June 1978, the Guideline on Air Quality Models was first incorporated by 

reference in regulations promulgated for PSD (40 CFR Parts 51.166 (formerly 51.24) and 52.21). 

See 43 FR 26388, 26398 (June 19, 1978); 51 FR 32176 (Sept. 1986); 53 FR 392 (Jan. 6, 1988). 

With respect to ozone, the EPA has explained that the complex chemistry of ozone is welldocumented and has historically presented significant challenges to the designation of particular 
147

models for assessing the impacts of individual stationary sources on the formation of these air 

pollutants.21

Because of these considerations, the EPA’s judgment has long been that it is not technically 

sound to designate with particularity specific models that must be used to assess the impacts of a 

single source on ozone concentrations. Id. Instead, the EPA has chosen to satisfy the 

requirements of Section 165(e)(3)(D) of the CAA through a process of determining particular 

models or other analytical techniques that should be used on a case-by-case basis. Id.; see also

40 C.F.R. part 51, App. W, section 5.2.1.c. Accordingly, the EPA has not previously interpreted 

and does not now interpret section 165(e)(3)(D) to create a requirement that every PSD applicant 

submit new air quality modeling whenever it seeks a PSD permit. Moreover, the opposing 

comment appears to assume that this provision applies directly to PSD permit applicants, but 

does not provide any analysis or explanation to support that assumption. Section 165(e) clearly 

directs EPA to promulgate regulations to address the requirements of this provision. Further 

description of how EPA interprets and implements the requirement under section 165(a)(3) of 

the CAA that a source demonstrate that its emissions will not cause or contribute to a violation of 

any NAAQS for ozone is provided in the Response to Comment I.1.A above and in Section I of 

the preamble to the final rule. 

In addition, the PSD regulations, at sections 51.166(l)(1) and 52.21(l)(1), provide that “all 

estimates of ambient concentrations [required under the relevant provisions] shall be based on 

applicable models, data bases, and other requirements specified in appendix W of this part 

(Guideline on Air Quality Models).” Thus, all modeling done to meet the PSD requirements 

must be based on Appendix W, unless a modification or substitution has been made pursuant to 

51.166(l)(2) and 52.21(l)(2). But as explained above and elsewhere in the Response to 

Comments and the preamble to the final rule, Appendix W does not require air quality modeling 

in all situations to satisfy the PSD requirements and does not require such modeling for all PSD 

sources that must provide an air quality impacts analysis for ozone. 

With respect to the comments regarding the Sierra Club’s July 28, 2010 petition as it relates to 

ozone, on January 4, 2012, EPA granted the Sierra Club petition requesting, among other things,

that the EPA initiate rulemaking to designate air quality models for ozone.22 The EPA agreed to 

engage in rulemaking to evaluate potential updates to its Guideline on Air Quality Models as 

published as Appendix W of 40 CFR Part 51 and, as appropriate, incorporate new analytical 

 

21 See Letter from Gina McCarthy, Assistant Administrator, to Robert Ukeiley, at 1-2 (Jan. 4, 

2012), available at 

http://www.epa.gov/scram001/10thmodconf/review_material/Sierra_Club_Petition_OAR-11-

002-1093.pdf. 

22 See Letter from Gina McCarthy, Assistant Administrator, to Robert Ukeiley, at 1 (Jan. 4, 

2012), available at 

http://www.epa.gov/scram001/10thmodconf/review_material/Sierra_Club_Petition_OAR-11-

002-1093.pdf.
148

techniques or models for ozone. Id. Consistent with that petition grant, the EPA has been going 

through a process to evaluate potential updates to Appendix W. Id. at 1, 3. As noted by the 

commenter, we have initiated actions to support rulemaking, including the 10th Conference on 

Air Quality Modeling in March 2012 where we discussed methods for addressing ozone. The 

EPA is following the existing process and procedures under Section 320 of the CAA to complete 

the appropriate rulemaking process in response to the petition. Consistent with this process and 

past practice, the EPA expects discussion to occur in 2015 at the 11th Modeling Conference and 

is planning to propose a rulemaking in 2015 to consider whether to update Appendix W. 

Meanwhile, PSD permit applicants should continue to follow the existing procedures to 

determine the appropriate method for evaluating their impacts on ozone formation. See 40 

C.F.R. part 51, App. W, section 5.2.1.c. Under the existing process, the appropriate methods are 

determined in consultation with the EPA Regional Office on a case-by-case basis. Id. 

Accordingly, the EPA will continue to work with permitting authorities to determine appropriate 

methods to satisfy the statutory and regulatory requirements for the air quality impacts analysis 

for ozone on a case-by-case basis.

Comment: PSD permitting and anti-backsliding

Commenter (0163) agreed that the obligation to implement nonattainment NSR requirements

associated with two or more standards means that the area must implement the thresholds and 

offset ratios associated with the highest nonattainment classification and objects to any proposal 

to weaken these NSR requirements.

Commenter (0180) stated EPA must determine NSR permitting obligations with reference to the 

area’s highest nonattainment classification, whether it is for the 2008 ozone NAAQS or a 

previous ozone NAAQS for which the area remains in nonattainment. The commenter believed 

that the EPA proposes that once areas are designated with respect to the 2008 ozone NAAQS, a 

particular area’s New Source Review requirements will be based on the highest nonattainment 

classification that has applied to that area (either the 2008 ozone NAAQS classification or a 

previous ozone NAAQS for which the area remains in nonattainment). 78 FR at 34200. This 

approach is compelled by the D.C. Circuit’s decision in SCAQMD. It is also appropriately 

protective and will help guard against worsening air quality. In SCAQMD, the court found that 

control measures pertaining to a prior, revoked NAAQS had to remain in place in order to 

prevent backsliding. In discussing the anti-backsliding implications of removing certain controls, 

the court noted that the Act “reflects Congress’s intent that air quality should be improved until 

safe and never allowed to retreat thereafter.” 472 F.3d at 900. Specifically, the court rejected 

EPA’s attempts to waive continuing obligations to implement control measures, including NSR, 

because “EPA was to enforce a high threshold for removing controls from a SIP.” Id. The court 

found that “something designed to constrain ozone levels is a ‘control,’ and this would include 

NSR” for the purposes of the Act’s anti-backsliding requirements. Id. at 902. As such, in order to 

comply with the statute, EPA must determine NSR permitting obligations with reference to the 

area’s highest nonattainment classification, whether it is for the 2008 ozone NAAQS or a 

previous ozone NAAQS for which the area remains in nonattainment. (0180)
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Response: In the final rule, the EPA is including anti-backsliding provisions similar to those 

proposed with only minor edits for clarification. Accordingly, in an area designated 

nonattainment for the 2008 ozone NAAQS and nonattainment for the 1997 ozone NAAQS at the 

time of revocation of the 1997 ozone NAAQS, the state will be obligated to implement the 

applicable requirements set forth in 40 CFR 51.1100(o). This could include, as applicable, antibacksliding requirements associated with the revoked 1-hour NAAQS if the area was also 

designated nonattainment for the 1-hour ozone NAAQS when that NAAQS was revoked. 

Nonattainment NSR applies (specifically, the major source thresholds and offset ratios) in these 

areas in accordance with their highest nonattainment classification under any ozone standard for 

which they are (or were at the time of revocation) designated nonattainment. It is also important 

to note, as included in the final rule, that the previous 1997 ozone NAAQS standard is revoked 

with this rule, therefore if an area is designated attainment for the 2008 ozone NAAQS but is still 

nonattainment for the 1997 ozone NAAQS, the area will be considered attainment upon the 

effective date of the rule due to its inherent stricter value, and the PSD program will be 

applicable for new and modified major sources. However, the rule does not relieve older sources 

from the maintenance of controls applied due to an earlier classification of nonattainment. Please 

refer to section 3.G for further discussion about the revocation of the 1997 ozone standard.

Comment: 18-month period for Appendix S waiver provision

Commenter (0180) stated EPA is correct that no exemptions beyond 18 months are possible. The 

commenter supported the EPA’s policy that states Appendix S governs in states that have yet to 

update their SIP requirements in newly designated nonattainment areas. The commenter 

considered this reading to be correct and appropriate in light of NRDC v. EPA, 571 F.3d 1245, 

and the EPA should revise 40 CFR § 52.24(k) as soon as possible, in accordance with the court’s 

decision. NRDC addressed implementation of the 1997 ozone standards, where the court held 

that EPA’s elimination of the 18-month limit on New Source Review exemptions violated the 

CAA’s anti-backsliding provisions. 

The commenter specifically indicated that section 110(a)(2)(c) of the CAA requires states to 

implement an NSR program. The commenter supposed the Act does not, however, specify what 

NSR requirements apply after an area is designated nonattainment but before the NSR SIP is 

approved. The commenter stated that historically, the EPA had applied Appendix S, which 

establishes interim NSR permitting requirements and provides for limited exemptions from NSR 

requirements. In 1980, EPA clarified that Appendix S should apply for no more than 18 months. 

That provision applied until 2005, when the rules implementing the 1997 ozone standards 

eliminated the 18-month permitting requirements. 

The commenter stated that in finding that this elimination violated the Act, the court held that

NSR is a “control” subject to section 172(e)’s backsliding prohibition []. Accordingly, the EPA’s 

elimination of the 18-month exemption limit violates section 172(e) if the resulting NSR 

requirement is “less stringent” than the existing requirement. Insofar as Appendix S now 

provides for waiver of NSR for an unlimited time pending SIP approval, it is plainly “less 

stringent” than the previous version which limited an NSR waiver to an 18-month term.” As 

petitioners argue, the EPA’s revision could delay implementing NSR controls in eligible 

nonattainment areas for years beyond the previous 18-month limit. Accordingly, we conclude 
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that the revision constitutes backsliding in violation of section 172(e). 571 F.3d at 1271. The 

commenter further concluded that in light of this vacatur, EPA is correct that no exemptions

from NNSR beyond 18 months are possible. The commenter agreed with the Agency that CFR § 

52.24(k) should be revised to reflect this ruling as expeditiously as possible. (0180)

Response: We agree with the commenter to the extent that the exemptions at issue pertain to the 

exemptions contained in section VI of Appendix S, which waives certain NNSR provisions that 

would otherwise be required for each applicant. While the specific waiver provisions of section 

VI should not be allowed beyond 18 months from the date of designation, the EPA does not 

consider the remainder of Appendix S as it pertains to an interim NNSR program prior to the 

approval of a state NNSR SIP, to be subject to an 18-month time limitation. Please see the 

preamble Section I.1 for a more detailed discussion. The EPA intends to revise section 52.24(k) 

to reflect the court’s vacatur of the extension of the 18-month time limit for section VI of 

appendix S; however, we did not propose such a revision in this rulemaking and we are not 

taking any final action in this rule to revise 52.24(k). 

Comment: Clarification on construction ban

Commenter (0154) noted that the EPA discusses (pp. 34200-34201) implications of ozone 

nonattainment on NSR, including the requirement to impose nonattainment NSR, and a court 

ruling in NRDC v EPA, 571 F.3d 1245 (D.C. Cir. 2009), wherein EPA says "The court 

dismissed the petitioners' general objections as "untimely" but vacated "the elimination of the 18-

month time limit for NSR waivers under Appendix S" on the grounds that it violated section 

172(e) of the CAA. Commenter (0154) requested that EPA rewrite this section of the proposal to 

make it clear whether a construction ban is in place for all nonattainment areas that do not have 

approved nonattainment NSR programs in place. Commenter (0154) asserted they have 

discussed this issue with the EPA’s regional offices on numerous occasions and it is still unclear 

what is meant by this section of the proposal.

Response: In NRDC v. EPA (571 F.3d 1245 (D.C. Cir. 2009)), the court considered the 

petitioners’ general objections to the NSR waiver provision contained in section VI of appendix 

S, as well as the EPA’s elimination of the 18-month limit on the applicability of that section. The 

court dismissed the petitioners’ general objections as “untimely” but vacated “the elimination of 

the 18-month time limit for NSR waivers under Appendix S” on the ground that it violated 

section 172(e) of the CAA (571 F.3d at 1276). As stated in our response to comment in Section 

2.I.1 above, the EPA intends to revise section 52.24(k) to reflect the court’s vacatur of the 

extension of the 18-month time limit for section VI of appendix S, but is not revising 52.24(k) in 

this rulemaking. In the meantime, as a result of the vacatur, no section VI waivers may be 

granted beyond 18 months from the date of designation.

With respect to the construction ban, the Clean Air Act Amendments of 1990 removed the 

construction ban. Under 40 CFR 52.24(k), after designation of a nonattainment area and prior to 

EPA's approval of a nonattainment NSR program for that area that meets the requirements of 

part D of title I of the CAA, the Emission Offset Interpretative Ruling, 40 CFR part 51, appendix 

S governs permits to construct. As stated in the EPA's June 6, 2013 proposal for this rule, 78 FR 

34200-201, in the EPA's 2005 promulgation of the phase 2 implementation rule for the 1997 
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ozone NAAQS, “the EPA revised section 52.24(k) to eliminate language stating that if a 

nonattainment area did not have an approved nonattainment NSR program within 18 months 

after designation, a construction ban would apply.” The June 6, 2013 proposal explains that the 

DC Circuit Court of Appeal's decision in NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009) left this 

revision of § 52.24(k) undisturbed, except with respect to the availability of waivers under 

section VI of Appendix S after the 18-month period has expired. Thus, commenter's concerns 

about a construction ban are unnecessary, as Appendix S to 40 CFR part 51 (with the exception 

of waivers under section VI of Appendix S after January 20, 2014) will continue to govern 

construction permits within respective nonattainment areas until the EPA approves a SIP revision 

containing a NNSR program that meets the requirements of part D of title I of the Act, 

specifically the NNSR requirements contained in 40 CFR 51.165.

Comment: Clarification on section VI waivers

Commenters (0155 and 0157) stated that the EPA should clarify that the reinstated 18-month 

deadline applies only to section VI waivers, and not to the applicability of the remainder of 

Appendix S, which states should continue to be able to use for NNSR beyond the 18-month 

period.

Response: The commenters are correct that no section VI waivers may be granted beyond 18 

months from the date of designation as nonattainment. The application of the remainder of 

appendix S, however, is not subject to an 18-month time limitation. Please see section I.1 of the 

preamble for the final rule for a more detailed discussion. 

Comment: PSD significant emission rate

Commenter (0180) stated EPA must revise the PSD significant emission rate and exemption 

from the ambient impact assessment requirement. The commenter indicated that the EPA stated 

that after the 1997 ozone NAAQS is revoked, PSD will apply in areas designated attainment for 

the 2008 ozone NAAQS. 78 FR at 34216. EPA should not revoke the 1997 ozone NAAQS. 

However, if EPA does revoke the 1997 standard, it would be arbitrary and capricious for EPA to 

apply PSD under EPA’s current PSD regulations to the 2008 ozone standard because there is no 

rational basis to apply certain parts of the PSD regulations to the 2008 ozone NAAQS. (0180)

EPA’s regulations implementing the prevention of significant deterioration program set various 

de minimis thresholds specific to each national ambient air quality standard. For example, the 

significant threshold for prevention of significant deterioration applicability for ozone is 40 tons 

per year of volatile organic compounds or nitrogen oxides. 40 CFR § 52.21(b)(23)(i)(2011). The 

significance threshold for carbon monoxide is 100 tons per year but the significance threshold for 

lead is only 0.6 tons per year. Id. 

These significance thresholds are generally based on the amount of pollution a polluter can emit 

before exceeding four percent (4%) of the ambient air quality standard expressed over a short 

term period or two percent (2%) of a standard expressed over an annual period. See e.g., 52 FR 

24, 678, 24,695 (July 1, 1987)(explaining that significant emission rates are set by “us[ing] an 

emission rate for which the modeled ambient [air pollution] concentration represent[s] 
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approximately 4 percent of the 24-hour primary standard.”). Another prevention of significant 

deterioration de minimis exemption is that any net emission increase of less than 100 tons per 

year or more of volatile organic compounds or nitrogen oxides does not have to perform an 

ambient impact analysis, including gathering ambient air quality data. 40 CFR § 52.21(i)(5)(i)(f) 

and note (2011). (0180)

The thresholds are considered de minimis in relationship to a specific national ambient air quality 

standard. See, e.g., 52 FR at 24695 (significant emission rate based on amount of pollution equal 

to 4 percent of NAAQS); 50 FR 13130, 13145 (April 2, 1985) (explaining basis for PSD 

implementation “significant emission rate” was based on four percent of the NAAQS); 45 FR at 

52707-08 (explaining that the PSD implementing regulations are established based on “de 

minimis” values set as a percentage of the most stringent NAAQS for each pollutant). EPA has 

gone so far as to determine that these de minimis values should never exceed five percent of the 

national ambient air quality standards. 45 FR at 52707 (“levels higher than five percent of the 

primary [NAAQS] were not seriously considered” because such impacts would consume too 

much of the allowable airshed resource); id. at 52 708 (for nitrogen oxides, which had a NAAQS 

expressed only as an annual standard, the de minimis rate was set at 2 percent of the NAAQS). 

When the national ambient air quality standard changes, EPA necessarily must evaluate the PSD 

implementation regulations. If it does not, the PSD regulations de minimis standards no longer 

maintain their previously chosen proportion to the national ambient air quality standards and 

therefore no longer represent only de minimis impacts in relationship to the new national ambient 

air quality standard. In other words, a change in the national ambient air quality standard without 

changing the prevention of significant deterioration de minimis threshold regulations yanks the

regulations from their national ambient air quality standard moorings. EPA is proposing to apply 

the current PSD regulation’s de minimis thresholds to the 2008 ozone NAAQS but EPA offers no 

analysis to support that these de minimis standards are actually de minimis in relationship to the 

2008 ozone NAAQS. Therefore, EPA must review and revise the PSD ozone significant 

emission rate and exemption from the ambient impact assessment requirement. (0180)

Response: The EPA disagrees with the commenter’s assertions that (1) the 1997 hour ozone 

standard should not be revoked and (2) an area should not be allowed to transition to PSD if the 

1997 standard is revoked and the area is attainment for the 2008 standard. Clearly, if an area is 

designated attainment for the 2008 ozone NAAQS, then it is meeting a stricter health based 

standard than the 1997 8-hour ozone NAAQS. Please refer to section 3.G for further details 

about anti-backsliding and the revocation of the 1997 ozone NAAQS.

The EPA does not agree that the Agency must update its PSD regulations every time the EPA

revises a NAAQS. The EPA does not interpret the CAA to require an automatic update of the 

PSD regulations with every revision of the NAAQS. In fact, arguments similar to the 

commenter’s arguments were raised in litigation in the US Court of Appeals for the Ninth 

Circuit, and that court agreed with EPA’s position, issuing a decision holding that EPA does not 

have a nondiscretionary duty under section 166(a) of the CAA to promulgate revised PSD 

regulations for ozone just because it had revised the ozone NAAQS. See WildEarth Guardians v. 

McCarthy, No. 12-16797, Slip. Op. at 9 (9th Cir., Dec. 1, 2014). That court reasoned that 

“Congress could have ... left to the agency’s discretion the responsibility for making whatever 
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revisions to [the PSD] regulations might be warranted when the corresponding NAAQS were 

revised.” Id. at 8.

The EPA also disagrees with the commenter’s position that the fact that the EPA has revised the

ozone NAAQS necessarily means it is arbitrary and capricious to apply the current PSD 

regulations to the 2008 ozone NAAQS and that the existing significant emission rates for ozone

cannot rationally be applied once the NAAQS have been revised unless the thresholds are 

updated to maintain the same proportion to the NAAQS previously used to justify these values. 

The EPA has existing PSD rules that apply to PSD permit applications that trigger permitting 

obligations for ozone, including significant emissions rates which are used to determine whether 

the increase in emissions of a pollutant from a new source or modification trigger PSD 

requirements for that pollutant. See, e.g., 40 C.F.R. §§ 51.166(b)(23)(i), 52.21(b)(23)(i). The 

PSD program is structured so that the PSD rules apply seamlessly to regulated NSR pollutants, 

including pollutants for which NAAQS exist, without needing to be updated for every NAAQS 

revision. See, e.g., 40 C.F.R. §§ 51.166(j)-(k), 52.21(j)-(k) (applying best available control 

technology requirements to each regulated NSR pollutant for which the proposed construction 

would trigger PSD and applying air quality impacts analysis requirements to any NAAQS). This 

approach is sensible because, while the EPA has discretion to modify the PSD rules when such 

modification is necessary or appropriate, not every revision to a NAAQS necessarily warrants a 

change to the PSD regulations. With respect to the significance of thresholds, the mere fact that 

the values for ozone were originally based on a particular proportion to the NAAQS in effect at 

an earlier time does not mean that those thresholds must be updated to maintain the same 

proportion to the NAAQS in perpetuity. The EPA retains the discretion to continue applying the 

existing values, even if emissions at that rate might have an impact equivalent to a different 

percentage of the NAAQS. The value need not reflect a particular percentage of the NAAQS, 

but rather reflect a level at which the “burdens” of regulating ozone precursors emitted in 

amounts less than that value “yield a gain of trivial or no value.” Alabama Power Co. v. Costle, 

636 F.2d 323, 361 (D.C. Cir. 1980). The fact that the NAAQS has changed does not demonstrate 

that the existing significant emissions rates for ozone precursors are no longer established at de 

minimis levels for ozone (e.g., levels below which regulation would yield trivial value).

The commenter does not provide any specific facts to demonstrate that emissions of ozone 

precursors at rates below the existence significance levels for ozone have more than a trivial 

impact and should be regulated in the NSR permitting program. Thus, the commenter does not 

show that the EPA should have exercised the discretion to propose revised significance levels for 

ozone in the proposed rule. This notwithstanding, since the EPA did not propose such a change 

to its regulations, the Agency is unable to promulgate revised significance rates for ozone in this 

final rule. However, the EPA will take the commenters concerns under advisement and consider 

whether additional action by EPA may be appropriate in the future. 

In addition, the EPA does not agree with the comment’s characterization of the 100 tons per year 

threshold in 40 CFR § 52.21(i)(5)(i) as a de minimis exemption from ambient impact analysis. 

The EPA does not consider the stated threshold to represent an automatic exemption from an 

ambient impact analysis. In the EPA’s response to Sierra Club’s July 28, 2010 petition for 

rulemaking, the Agency stated, ... this 100 tons per year (TPY) value has been used by some 
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permitting authorities in a manner similar to a [significant impact level] to assess whether a 

detailed air quality analysis should be conducted for ozone.23 While [certain prior EPA] 

statements suggest a less rigorous analysis may be appropriate for sources emitting less than 100 

TPY of these precursors [NOx and VOC], they have not been revisited by the EPA since the 

promulgation of the 8-hour ozone NAAQS and do not reflect a categorical conclusion by the 

EPA that every source emitting less than 100 TPY of NOx or VOCs will not cause or contribute 

to a violation of the current ozone NAAQS. 

The EPA has since initiated actions to support rulemaking in response to Sierra Club’s petition, 

including the 10th Conference on Air Quality Modeling in March 2012 where we discussed 

methods of addressing ozone and secondary PM2.5 impacts in PSD air quality impacts analyses 

and released draft guidance for PM2.5 permit modeling in March 2013. The EPA is following the 

existing process and procedures under Section 320 of the CAA to complete the appropriate 

rulemaking process in response to the petition. Consistent with this process and past practice, 

the EPA expects further discussion to occur at the 11th Modeling Conference and is planning to 

propose a rulemaking in 2015 to consider whether to update Appendix W.

2. Offsets 

Comment: Support offsets outside NAA

Commenter (0140) suggested that major source construction and major modification offsets 

should be able to be obtained within the same expanded area from which the state would be able 

to obtain emission reductions to fulfill RFP. The commenter indicated that for many areas that 

are on the verge of nonattainment such as Austin, there are only a very limited number of major 

sources within the MSA from which a company could obtain an offset to build a new facility or 

modify an existing facility, but there are many very large sources elsewhere within the AQCR or 

in adjacent areas contributing to nonattainment that would not be included in the pool of 

available offsets or be required to obtain an offset for major expansion or new construction. This 

leaves open the very real possibility of companies opening plants just outside the boundaries of 

the MSA but close enough to contribute to ozone problems. (0140)

Response: The EPA believes the commenter’s suggestion conflicts with the statutory 

requirements for offsets restricting geographic areas from where offsets can be obtained. In 

accordance with the requirements under section 173(c)(1) of the CAA, emissions offsets for 

purposes of nonattainment NSR permitting must be obtained from the same source or same 

 

23 Letter from Gina McCarthy, Assistant Administrator, to Robert Ukeiley (Jan. 4, 2012), at 4 

available at 

http://www.epa.gov/scram001/10thmodconf/review_material/Sierra_Club_Petition_OAR-11-

002-1093.pdf. 
155

nonattainment area as where the source requiring the offsets is located, except that the state may 

allow a source to obtain offsets from another nonattainment area if (1) that area has an equal or 

higher nonattainment classification than the nonattainment area in which the source requiring the 

offsets is located, and (2) emissions from that other area contribute to a violation of the NAAQS 

in the nonattainment area in which the source requiring the offsets is located. To the extent that 

the commenter suggests that offsets should be able to be obtained from an attainment area, or 

from a nonattainment area that does not meet these criteria, that suggestion would be inconsistent 

with the CAA. Accordingly, the EPA is not revising the existing regulatory requirements as to 

where emissions offsets may be obtained to allow such use of offsets. The EPA encourages the 

state to consider offset-related issues when recommending nonattainment area boundaries. CAA 

section 107(d)(1)(A) requires that nonattainment areas be comprised both of areas not meeting 

the NAAQS and nearby areas contributing to the area not meeting the NAAQS. If the areas 

outside of the MSA (in the AQCR or adjacent areas) mentioned by the commenter are nearby 

areas that contribute to nonattainment, CAA section 107(d)(1)(A) requires that these areas be 

included in the nonattainment area.

With regard to the commenter’s assumption that states may use emissions reductions from 

outside a nonattainment area to fulfill RFP, please refer to II.C.7 of the RTC for further 

information.

Comment: State discretion 

Commenter (0152) believed that EPA’s proposal implied that offset banks or registries could 

only be established in economic development zones as determined by the Housing and Urban 

Development Secretary. The commenter believes such a position usurps a State's right to set up 

offset bank and registry programs and that such programs should be able to be set up anywhere 

within that state where appropriate modeling and technical analysis continues to show that with 

such programs, attainment is still achieved.

Response: The comment appears to be based on a misunderstanding of the EPA’s position 

concerning offset banks. The EPA does not take the position that offset banks (and registries) can 

only occur in economic development zones. To the contrary, the final rule states, “States can 

help facilitate continued economic development in a nonattainment area by establishing offset 

banks or registries. Such banks or registries can help new or modified major stationary source 

owners meet offset requirements by streamlining identification and access to available emissions 

reductions. Some states have established offset banks to help ensure a consistent method for 

generating and using NOx and VOC offsets.24 Offsets in these areas are generated by emissions 

 

24 See, for example, emission reduction credit banking programs in Ohio (OAC Chapter 3745-

1111) and California (H&SC Section 40709).
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reductions that meet specific creditability criteria set forth by the SIP consistent with EPA 

regulations. See existing 40 CFR 51.165(a)(3)(ii)(A)-(J) and part 51 Appendix S section IV.C.” 

The Agency respectfully disagrees, however, with the comment insofar as it suggests that such 

programs should be able to be established anywhere in a state. The Act requires new and 

modified major sources in nonattainment areas to secure emissions reductions (i.e., “offsets”) to

prevent proposed emissions increases from new and modified major sources from interfering 

with reasonable progress toward attaining the NAAQS. Section 173(c) of the CAA establishes 

specific requirements that such emissions reductions must satisfy in order to be used as offsets 

for purposes of nonattainment NSR permitting, including a requirement that the offsets come 

from the same source or a source in the same nonattainment area as the source requiring the 

offsets, though the State may allow use of offsets from another nonattainment area that meets 

certain statutory criteria. Thus, the Act itself limits States’ discretion as to the areas from which 

offsets can be obtained for NNSR purposes, and this limits the areas from which offset banks 

may draw from for purposes of NNSR. These limitations are reflected in and implemented by 

existing EPA regulations. See 40 CFR 51.165(a)(3)(ii)(F) and 40 CFR Part 51, Appendix S, 

Section IV.D. Those requirements are not being revised in this rulemaking.

3. Interpollutant Offset Substitution

Comment: Support the proposal for interprecursor trading and suggest additional actions

Commenters (0129, 0130, 0141, 0143, 0145, 0153, 0159, 0173, 0175 and 0178) stated that they 

support the proposal to allow substitution between the ozone precursors NOx and VOC for the 

purpose of obtaining offsets for nonattainment NSR permitting. Some of the commenters offered 

specific suggestions about requirements that EPA should establish for such substitutions, as 

reflected in the following paragraphs. 

One commenter stated that the EPA acknowledges that allowing states to develop provisions 

which make it easier for new or modified major sources to satisfy offset requirements with 

interpollutant offset substitutions may facilitate new source growth and continued economic 

development. Specifically, these provisions would allow substitution of NOx emissions 

reductions to satisfy VOC offset requirements and vice versa. The commenter strongly 

encouraged the EPA to incorporate this section in the final rule for implementing the 2008 

Ozone NAAQS as it would provide more flexibility in achieving offset requirements in 

nonattainment areas where VOC control technology has fully matured. (0129)

Another commenter stated that permits for facilities to construct or modify in nonattainment 

areas need to ensure that the expansion or new facility will not hinder progress toward 

compliance with the NAAQS. However, requiring facilities to obtain offsets for pollutants that 

only minimally reduce ozone concentrations is overly burdensome and should be streamlined. In 

areas where NOx is the predominant ozone precursor, which is the case in most areas on the 

eastern seaboard, NSR offset requirements for areas within and outside the OTR should reflect 

this fact. The commenter believed that in these areas, NSR rules should not mandate that VOC 
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offsets be acquired for major permit actions. This commenter also suggested that such an 

exchange should also be able to be implemented in the OTR regions, as well as in nonattainment 

areas outside of the OTR. (0130)

Another commenter agreed and supported the retention of "interpollutant offset substitution" 

provisions in the final rulemaking. The commenter stated their agency has worked closely with 

EPA Region III and potentially affected facility owners and operators in southeastern 

Pennsylvania to obtain approval of interpollutant offset substitutions for NOx emission reduction 

credits to satisfy VOC offset requirements and vice versa. DEP believes that the flexibility 

provided by interpollutant offset substitutions, when feasible, is essential for continued 

improvement in the Commonwealth's economy. (0143)

Another commenter urged the EPA to approve any offset substitution ratio shown to be 

consistent with air quality planning in the relevant nonattainment area. Offset substitution ratios 

can incentivize air quality improvements in ways such as the following:

• Substitution ratios can enable more projects that are subject to nonattainment offset 

requirements greater than 1: 1. In many areas, offset substitution may be the only realistic option 

to enable major industrial projects. Because newly constructed facilities in nonattainment areas 

use state-of-the-art emission controls and must more than offset their emissions increases, each 

new project should incrementally reduce emissions in the airshed. 

• Substitution ratios can make voluntary emission control measures cost effective. For example, 

if NOx control costs are high in an area, a source seeking to offset VOC might look instead to 

VOC control projects. However, if each unit of NOx reduction could substitute for a higher 

quantity of VOC (based on a demonstration that NOx contributes more than VOC to ozone 

formation in the nonattainment area), the source could be appropriately incentivized to prefer the 

same controls (i.e. NOx controls) that more effectively reduce ozone levels. Thus, a substitution 

ratio could align the source's control preferences with the area's air quality needs. (0173)

Another commenter stated that it supports the U.S. EPA’s proposal to allow additional flexibility 

for satisfying new source review (NSR) pollutant offset requirements. Specifically, the 

commenter supported allowing nitrogen oxide (NOx) offsets to satisfy VOC offsets, and vice 

versa. Wisconsin supports the proposal to allow states to establish offset trading ratios; however, 

the U.S. EPA should clearly articulate the approval process for ratios in the rule. In addition, the 

U.S. EPA should establish some default trading ratio in rule that states could use if they do not 

have the ability to conduct complex photochemical modeling. (0175)

Another commenter stated that it supports interpollutant offset substitution [78 FR 34201] among 

ozone precursors similar to what was authorized in EPA’s final 2008 Fine Particulate Matter 

(PM2.5) NAAQS implementation rule for PM2.5 precursors. (0178)

Commenter (0153) supported the proposal to allow states to establish interpollutant offset 

substitution provisions and to allow states to determine appropriate exchange rates, and stated it 

is important that the decision on whether to allow interpollutant offset substitution, and the 
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specific requirements of such a program, should be clearly at the discretion of each state. The 

commenter believed that State air pollution control agencies are in the best position to determine 

how a program could impact nonattainment area(s) within their boundaries. States should be 

allowed to 1) determine whether or not to allow interpollutant offsets, 2) to limit interpollutant 

offsets to a certain direction (e.g., to allow for NOx emission reductions to be used to offset VOC 

increases, but not vice-versa, in a NOx limited area), 3) determine how and when exchange rates 

should be set (e.g., one-time state-wide or county-specific ratios, determined on a case-by-case 

basis, etc.). EPA should set clear, unambiguous, minimum requirements for approvable offset 

substitution provisions so that state agencies can craft programs with a reasonable assurance of 

EPA approval, which will allow EPA to promptly review and act on state interpollutant offset 

substitution programs. Approval of such programs should be made by EPA regional offices with 

guidance from headquarters. The final SIP requirements rule should also allow states to 

implement adopted offsite substitution provisions unless disapproved by EPA (i.e., not make 

EPA approval a prerequisite for allowing interpollutant offsets). (0153)

Response: The EPA agrees with the comments that support allowing trades between the ozone 

precursors VOC and NOx for purposes of satisfying the offset requirements for nonattainment 

NSR permitting. As explained in more detail in the preamble to the final rule, the EPA is 

amending the regulatory text in both 40 CFR 51.165 and 40 CFR part 51, Appendix S as a 

logical outgrowth of the proposal and the submitted comments to ensure that the offset 

provisions of both rules are consistent with our proposal and our ongoing position to allow such 

trades for the ozone precursors (VOC and NOx). In particular, the EPA is finalizing revisions to 

40 CFR 51.165(a)(11) and part 51 Appendix S IV.G.5 in this action. These changes in the 

regulatory text are intended to clarify that interprecursor trading continues to be an option for the 

ozone precursors VOC and NOx, as long as such trades are consistent with existing policy and 

legal requirements; these regulatory revisions are not intended to change the underlying 

requirements for such trades. 

Because the agency is not changing the underlying requirements for such interprecursor trades, 

we are not taking action in this rulemaking on the specific suggestions offered by commenters. 

With regard to a commenter’s recommendation that interprecursor trading be allowed in the 

OTR, the changes in the regulatory text in this action do not specifically address the use of such 

trading within the OTR regions and do not change existing law or policy with regard to such 

trading in such areas.

With regard to the commenters’ suggestions that the EPA should establish default trading ratios 

or establish a particular process or specific criteria for such approvals in this rulemaking, the 

Agency did not propose to, nor is it, codifying such ratios, criteria, or procedures. The Agency is 

not establishing default interprecursor trading ratios in this rule due in part to the variability in 

specific circumstances and the contribution and classification requirements of CAA §173. As 

indicated in the previous response, the EPA encourages State and local air agencies to seek 

support from the appropriate EPA Regional Office for ozone modeling concerns. The agency 

does not see a need to change the existing criteria and procedures at this point. Therefore, the 

EPA respectfully disagrees with the commenters’ suggestion that EPA promulgate default 

trading ratios, or establish the commenters’ suggested criteria and procedures (0153, 0173, 
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0175).

In response to comment (0153), the EPA did not propose to add, nor is it finalizing, regulatory 

language to allow states to use offset ratios prior to EPA approval. While permitting authorities 

are not required to allow such interprecursor trading, the EPA does not believe that establishment 

of interprecursor offset trading programs should be at the sole discretion of each state, but rather 

believes that such programs should continue to be addressed through the existing framework of 

reciprocal interstate offset trading agreements, federal-state cooperation and through the existing 

policy and legal requirements.

Comment: lnterpollutant trading—confirm it is allowed under existing policy

Commenter (0151) requested that EPA confirm in the final rulemaking that interpollutant trading 

is allowed under existing federal ozone policy and that states can provide for such trading in their 

SIPs. The commenter added that it is important that states be allowed to provide for in their SIPs 

for interpollutant trading. Particularly in areas of the country like the Northwest which are NOx

limited due to forests and other environmental factors, it will be important to allow NOx

reductions to offset VOC increases for the purposes of lowering ozone. (0151)

Response: As explained further in the preamble in section III., I, 1, and above in section 2.0, I, 1, 

the EPA is taking action in this final rulemaking to amend the regulatory text in both section 

51.165 and Appendix S as a logical outgrowth of the proposal and the submitted comments to 

ensure that the offset provisions of both rules are consistent with statements made in our 

proposal notice, as well as our ongoing position to allow such trades for the ozone precursors 

(VOC and NOx) in SIPs. See revised 40 CFR 51.165(a)(11) and part 51 Appendix S IV.G.5. 

These changes in the regulatory text are intended to clarify that interprecursor trading continues 

to be an option for the ozone precursors VOC and NOx, as long as such trades are consistent with 

existing policy and legal requirements; these revisions are not intended to change the underlying 

requirements for such trades.

Comment: lnterpollutant offset default ratios by region

Commenter (0141) supported the establishment of trading ratios between NOx and VOC 

precursors and asked EPA to allow the establishment of default ratios on a regional basis, rather 

than by individual nonattainment areas. 

Commenter (0175) stated EPA should establish some default trading ratio in rule that states 

could use if they do not have the ability to conduct complex photochemical modeling if needed 

to establish default ratios.
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Response: As explained in 3.0, I, 2, of this document and in the preamble to the final 

rulemaking, the EPA is taking action in this final rulemaking to amend the regulatory text in both 

section 51.165 and Appendix S to ensure that the offset provisions of both rules are consistent 

with our ongoing position to allow such trades for the ozone precursors VOC and NOx.

With regard to the commenters’ suggestions that the EPA should establish trading ratios between 

NOx and VOC precursors, the Agency did not propose to, nor is it, codifying default 

interprecursor trading ratios in this rule due in part to the variability in specific circumstances 

and the contribution and classification requirements of CAA § 173. States and local air agencies 

are encouraged to seek support from the appropriate EPA Regional Office for ozone modeling 

concerns. Therefore, the EPA respectfully disagrees with the commenter’s suggestions that the 

EPA establish default trading ratios at this time.

Comment: Use of existing studies to eliminate the VOC offset requirements 

Commenter (0130) suggested that the proposal should allow states to use existing studies to 

eliminate the need for VOC offsets in certain areas where VOC emission reductions have been 

shown to be only minimally effective in reducing ground-level ozone concentrations. 

Response: The EPA begins by noting that Congress has created an express statutory framework 

that establishes certain circumstances under which NOx requirements do not apply or may be 

limited. In particular, in subpart 2 of part D of the Act, section 182(f) requires States to apply the 

same requirements under that subpart to major stationary sources of NOx as are applied to major 

stationary sources of VOC. However, section 182(f) additionally specifies circumstances under 

which these NOx requirements may be limited or would not apply (“NOx waiver”). While 

Congress could have created a VOC waiver at the same time the section 182(f) NOx waiver 

provisions were enacted (or subsequently), Congress did not do so (and has not since done so). 

Furthermore, while ambient air analyses show that NOx emission reductions can be 

counterproductive under certain circumstances, we do not see a similar case for VOC. 

The legislative history of the 1990 CAA Amendments contains some discussion of the NOx

waiver that Congress established in section 182(f). In the process of adding the new NOx 

requirements to the Act, Congress recognized that NOx reductions would help achieve ozone 

reductions in some ozone areas, but stated that "there are some instances in which NOx 

reductions can be of little benefit in reducing ozone or can be counter-productive, due to the 

offsetting ability of NOx to ‘scavenge’ (i.e., react with) ozone after it forms" (H.R. Rep. No. 490, 

101st Congress, 2nd Sess., at 204). Congress also provided for additional review and study under 

section 185B "to serve as the basis for the various findings contemplated in the NOx provisions" 

(H.R. Rep. 490 at 257). Pursuant to section 185B, the EPA, in conjunction with the National 

Academy of Sciences (NAS), conducted a study on the role of ozone precursors in tropospheric 

ozone formation. The joint study examined the role of NOx and VOC emissions, the extent to 

which NOx reductions may contribute or be counterproductive to achieving attainment in 

different nonattainment areas, the sensitivity of ozone to the control of NOx, the availability and 

extent of controls for NOx, the role of biogenic VOC emissions, and the basic information 

required for air quality models. With respect to VOC, the NAS report from the study states that 
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“control of VOCs never leads to a significant increase in ozone” (December 1991 NAS report, 

Rethinking the Ozone Problem in Urban and Regional Air Pollution, page 377). The final section 

185B report, which was submitted to Congress on July 30, 1993, incorporates this NAS report 

along with an EPA report addressing the availability and extent of NOx controls. Thus, the final 

section 185B report indicates that there is not the same technical or scientific basis for a VOC 

waiver as there exists for the NOx waiver. 

The commenter does not identify any other specific, existing studies that might support a waiver 

provision for VOC. Moreover, the commenter does not identify any statutory basis for its 

recommended VOC waiver and does not provide any explanation for why such a waiver would 

be consistent with the statutory requirements for offsets under the CAA. Accordingly, the EPA is 

not taking action in this rulemaking to establish such a waiver for VOC offsets. However, the 

EPA does support the use of interprecursor trading which is discussed in more detail in response 

to comments 2.0, I,A above.

Comment: Use existing EPA regional modeling for approval of offset trading ratios

Commenters (0155 and 0157) recommended that the EPA consider using its regional modeling 

to specify presumptive offset trading ratios that air quality control agencies may use for each 

ozone nonattainment air quality control region, without requiring agencies to conduct their own 

complex regional modeling. Alternatively, commenters (0155 and 0157) suggested that the EPA 

might provide examples of where such analyses have been successful in obtaining EPA approval 

of offset trading ratios, so that other agencies can follow the same procedures.

Response: As explained in more detail in the response to comments in 2.0.I. 2, above, the EPA 

did not propose to establish presumptive offset ratios as described by the commenter and is not 

taking action to establish such ratios in this final rule. However, the Agency continues to 

recommend consultation with the Regional Office for ozone modeling concerns. Therefore, the 

EPA respectfully disagrees with the commenter’s suggestions that the EPA establish default 

trading ratios.

4. Economic Development Zones

Commenters (0145 and 0159) stated that they support the proposal with respect to emissions 

offset relief in Economic Development Zones. The commenters supported this proposal for the 

reasons asserted by EPA. LCA agrees with the approach of states setting aside growth 

"allowances" to support new or modified major sources, rather than obtaining offsets via facilityspecific emissions reductions or shutdowns in the nonattainment area. (0159)

Response: As explained in Section III.I.3.c of the preamble to the final rule, section 173(a)(1)(B) 

of the CAA authorizes the Administrator, in consultation with the Secretary of Housing and 

Urban Development (HUD), to identify areas within nonattainment areas as "zone[s] to which 

economic development should be targeted." Under this section, new or modified major stationary 

sources that locate in such a zone are relieved of the NSR requirement to obtain emission offsets 

if (1) the relevant SIP includes an NSR nonattainment program that has established emission 
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levels for new and modified major sources in the zone ("growth allowance"), and (2) the 

emissions from new or modified stationary sources in the zone will not cause or contribute to 

emission levels that exceed such growth allowance. Section 172(c)(4) of the CAA requires that 

the growth allowance be consistent with the achievement of reasonable further progress, and that 

it will not interfere with attainment of the applicable NAAQS by the applicable attainment date 

for the nonattainment area. The EPA is willing to work with HUD and states to identify potential 

areas that could be identified as EDZs.

5. SIP Submittal Date for Nonattainment NSR rules

Commenter (0151) noted that while the proposal notice proposes dates for submitting certain 

ozone nonattainment area SIP elements, the proposal did not discuss a SIP submittal deadline for 

nonattainment NSR rules for ozone. The commenter indicated that one of these dates that must 

be met sooner than later is not even discussed in the Notice and that is for states to adopt/make 

nonattainment “New Source Review (NSR)” applicable in expanded nonattainment areas or 

adopt NSR requirements within 18 months, as required by the D.C. Circuit in NRDC v. EPA 

(Phase 2 Ozone Plan).

Response: The commenter is correct that the EPA did not propose a specific due date for 

nonattainment NSR SIPs for the 2008 ozone NAAQS. This final rule includes a due date of 3 

years from the effective date of designation for states with nonattainment areas for the 2008 

ozone NAAQS to submit their NNSR SIPs. Please see section III.A.4 of the final rule for 

additional discussion. 

We disagree with the commenter’s conclusion that, because the NRDC v. EPA court decision 

vacated the EPA’s elimination of the 18-month limit for Appendix S, the court required NNSR 

SIPs to be submitted within 18 months from the date of designation as nonattainment. The EPA 

believes that the court decision applied only with respect to the NSR waiver in section VI of 

Appendix S—not to Appendix S as a whole—(as described in the response to comments at 2. 

2.I.1.E-G of this document and in section I.1 of the preamble to the final rule.) . 

J. What are the emission inventory and emission statement requirements?

1. Emissions inventory

Comment: AERR data elements

Commenter (0179) agreed with aligning the data elements requirements with AERR. However, 

commenter added that if the EPA decides to pursue ambient monitoring approach for RFP 

determinations, the agency may need to consider adjustments to details of the emission inventory 

requirements.

Response: The EPA concurs with this comment. The EPA has not finalized the alternative air 

quality approach (See response to comments in section 2.C.5), therefore, the details requested by 
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the commenter to adjust the emission inventory requirements are not necessary at this time. 

Comment: Marginal area emissions inventory reporting

Commenter (0169) did not agree with the need for Marginal area emissions inventory reporting 

as no modeling is required to be redesignated to attainment. Commenter (0169) stated that, any 

emissions inventory reporting for Marginal areas outside of what has already been collected into 

the National Emissions Inventory (NEI) seems to be redundant, burdensome and unnecessary.

Response: The EPA disagrees with this comment because this requirement stems from specific 

requirements in the CAA. Thus, the EPA does not have the discretion to eliminate the 

requirement for Marginal area inventory reporting. Section 182(a)(1) clearly requires such an 

inventory to be submitted as part of the Marginal area plan. Further, this inventory would need to 

reflect ozone season day emissions, consistent with other provisions of this final rule for 

implementation of the 2008 ozone NAAQS.

Comment: Partial county areas

Commenter (0169) stated, the SIP Requirements Rule is lacking in that partial county areas are 

not addressed. Commenter (0169) provided the following additional points. The Commenter 

stated that, there are instances where partial county data (which is what is required by the SIP 

Requirements rule at first glance) will be terribly burdensome for states to tease out of a previous 

AERR submittal. AERR requirements are met by full county emissions inventory submittals. 

Pulling out partial county data in some instances will provide little benefit as the theory behind a 

nonattainment area is that most of the area emissions are contained within the nonattainment area 

and adding emission reporting from the rest of the county will have a negligible impact on the 

data. Certain MSAs and CSAs, however, encompass very small portions of multiple counties and 

nonattainment area boundaries may be drawn based on MSAs and CSAs rather than county lines. 

In these instances, there may be significant benefit to partial county data submittals despite the 

resource intensive process required to pull that data from AERR reporting. The Department 

believes apportionment tools have been developed to be utilized on a case-by-case basis and that 

states should be granted deference. The Department also suggests the EPA put this case-by-case 

deference in rulemaking rather than presumed practice.

Response: The EPA concurs that, the rule does not specifically address partial county areas, 

which allows for flexibility in implementing the inventory requirements of the rule. The EPA 

further agrees that in some cases, there is no benefit for areas to develop partial county 

inventories. This issue will be addressed in the updated emission inventory guidance, and 

regional offices, and states will continue to work together to identify areas for which partial 

county emissions are needed for proper implementation of the 8-hour ozone NAAQS.

For areas in which partial county emissions are needed, the EPA provides allocation approaches 

that are also used for air quality modeling assignment of county-wide emissions to grid cells. The 

data are publicly available for download and use. These are the spatial allocation surrogates 

issued with the EPA’s modeling platforms on the Emissions Modeling Clearinghouse section of 

the EPA’s website. The EPA encourages use of these data or commonly available Geographic 

Information System (GIS) tools for estimation of partial-county emissions.
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Comment: AERR amendments

Commenter (0146) stated concern that, the EPA’s proposal is inconsistent with the amendments 

currently proposed for the Air Emissions Reporting Requirements (AERR) rule. Commenter 

(0146) provided the following additional points. The commenter pointed out that the EPA’s 

proposal references AERR for purposes of defining the data elements for the emissions 

inventories, but the AERR is currently under rulemaking and the proposed amendments remove 

ozone-related emissions reporting requirements, definitions and guidance. The proposed ozone 

implementation rule’s background section also references the EPA’s August 2005 inventory 

guidance. That guidance document references the Consolidated Emissions Reporting Rule 

(CERR), which no longer exists and specifies that ozone season inventories should be reported 

as actual annual and actual summer weekday inventories. The Commenter indicated that, states 

need clear, consistent, and updated guidance on ozone inventory development. The NESCAUM 

states recommend that the EPA clearly indicate in the body of the final ozone implementation 

rule—as it did for the previous ozone implementation rule—what is required for ozone 

inventories and for RFP and contingency measure baselines. The final rule must also reference 

appropriate guidance. Any references to the AERR should be clearly addressed to ensure that the 

proper ozone season inventories are developed.

Commenter (0163) stated, the recently proposed revision to the AERR would eliminate a critical 

ozone planning element. Commenter (0163) stated that, unless the requirement to develop an 

inventory of daily ozone season emissions as part of the AERR is retained and that, requirement 

would need to be included as part of the ozone implementation rule.

Commenter (0177) stated that, the proposed rule is unclear as to whether the previous obligations 

for nonattainment areas to quantify ozone precursor emissions based on a "typical summer day" 

rather than annual emissions because the AERR is currently open for comment and proposes to 

eliminate the daily and seasonal reporting requirements relevant to ozone. Commenter (0177) 

provided the following additional points. The Commenter stated that, given the challenges of 

addressing HEDD and likely need to design control programs that address peak ozone levels, the 

EPA should clarify the final implementation rule and the AERR to specify that emission 

inventories must be representative of days that produce high ozone. On August 5, 2013, [the 

Connecticut Department of Energy and Environmental Protection] submitted comments on the 

proposed AERR urging the EPA to retain the daily and seasonal emissions reporting 

requirements relevant to ozone as a critical tool for ozone planning. (0177)

Commenter (0178) also discussed the AERR rule and proposed amendments as follows: The 

proposed emission inventory requirements under 51.1115 rely on 40 CFR part 51, the AERR 

specifically, the ozone-relevant data elements required by the ozone implementation rule are 

listed in AERR Appendix A tables 2A, 2B, 2C and 2D. The EPA is currently revising the AERR 

[EPA-HQ-OAR-2004-0489] with a proposal to remove the requirements to report daily and 

seasonal emissions. The proposed AERR would also change the required data elements in Table 

2A and 2B, while removing Tables 2C and 2D. The Air Program supports the changes to the 

AERR, specifically changing ozone season emission data to an optional element and the 
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streamlining of tabular data elements. The EPA should review the ozone implementation rule 

proposal to ensure data states are requested to report is required by either the CAA section 

182(a)(3)(A) obligation, the "Guidance on the Implementation of an Emission Statement 

Program," or "Emissions Inventory Guidance for Implementation of Ozone and Particulate 

Matter National Ambient Air Quality (NAAQS) and Regional Haze Regulations." The Air 

Program intends to voluntarily submit ozone season emissions information triennially under the 

revised AERR as it would satisfy the CAA section 182(a)(3)(A) periodic inventory obligation, in 

addition to provide the public with an opportunity to review and comment on the documentation 

of the inventory. (0178)

Commenter (0175) supported the EPA’s proposal to allow states to rely on their 3-year cycle 

inventory to meet the CAA section 182(a)(3)(A) requirement. 

Commenters (0155 and 0157) noted that, the AERR is being revised and the EPA has proposed 

to remove the provisions referenced in this proposal. Therefore, Commenters (0155 and 0157) 

stated, the EPA should either amend the AERR to reincorporate the cited provisions or include in 

the ozone SIP requirements rule provisions for developing an ozone season day emission 

inventory rather than an annual inventory.

Response: The EPA concurs that, an inconsistency was created between the proposed AERR 

updates and this proposal. As suggested by several Commenters, the EPA has updated the 

language in the final rule to specifically denote that emissions are required to be submitted as 

ozone season day emissions, reflecting the considerations leading to nonattainment in the area. 

The ozone season day field will be defined as part of the update to the emission inventory 

guidance.

Comment: Emission inventory guidance

Commenters (0155 and 0157) supported the EPA’s proposal to allow states to defer public 

hearings on certain inventories until such time as the areas adopt and submit their RFP plans or 

attainment demonstrations that rely on these inventories.

Commenter (0163) supported the EPA’s proposal to follow September 29, 1992, guidance 

entitled, ''Public Hearing Requirements for 1990 Base-Year Emissions Inventories for Ozone and 

Carbon Monoxide Nonattainment Areas'' in implementing the emissions inventory requirements 

under the CAA sections 182(a)(l) and 182(a)(3)(A) for purposes of the 2008 ozone NAAQS. 

Commenter (0163) stated, the EPA should update its guidance on ozone inventory preparation 

and documentation, "Example Documentation report for 1990 Base Year Ozone and Carbon 

Monoxide SIP Emissions Inventories," March 1992 (EPA-450/4-92-007), since this guidance 

does not recognize the developments in software and technology which could reduce the 

workload necessary to prepare documentation. 

Response: For purposes of the 2008 ozone NAAQS, the EPA is not finalizing the proposed 

approach, where we advised that states could follow our existing September 29, 1992, guidance 
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titled, “Public Hearing Requirements for 1990 Base-Year Emissions Inventories for Ozone and 

Carbon Monoxide Nonattainment Areas” in implementing certain SIP adoption and submission 

procedures for the emissions inventory requirements under the CAA sections 182(a)(1) and 

182(a)(3)(A). In that guidance, the EPA indicated it could provide states with a time-limited “de 

minimis” deferral of the CAA’s state public hearing requirement for the emissions inventory SIP 

revision required to be submitted for each nonattainment area within 2 years of the date of 

designation. The EPA continues to believe that there are valid policy reasons to provide such a 

deferral since the inventories alone do not have significant regulatory context without the 

accompanying area-specific RFP plans or attainment plans, which are not required to be 

submitted until the 3rd year after designations at the earliest. However, as a general matter the 

CAA clearly requires that SIP submittals, including emissions inventories (See CAA sections 

182(a)(1) and 182(a)(3)(A)), must meet the requirements of the CAA section 110(a)(2), which 

includes the requirement that the state provide reasonable notice and public hearing for SIP 

submittals. As there is nothing in these CAA provisions that provides for waiver or delay of the 

public notification and hearing requirements specified in CAA section 110(a), de minimis or 

otherwise, we no longer believe it is appropriate to advise states to follow the 1992 guidance. We 

instead remind states that the EPA’s implementing regulations at 40 CFR Part 51 (Requirements 

for Preparation, Adoption and Submittal of Implementation Plans) provide flexibility for states to 

streamline SIP-related public notification and hearing procedures (for example, only holding a 

public hearing if one is requested, per 40 CFR § 51.102), and we encourage states to take 

advantage of those provisions in meeting the emissions inventory requirements under the CAA 

sections 182(a)(1) and 182(a)(3)(A).

The EPA concurs that, the ozone inventory preparation and documentation guidance from March 

1992 is outdated and plans to issue an updated draft guidance document with the final rule to 

implement the 2008 ozone standard. 

2. Emissions statement requirements

Comment: Commenter (0163) supported the proposal that the Emission Statement SIP be due 2

years after the effective date of the designations as prescribed in the CAA section 182(a)(3)(B). 

Commenter (0169) agreed with and appreciated the EPA's acknowledgement that areas which 

were nonattainment for a previous NAAQS have already implemented emissions statement 

requirements. The Commenter added that, if states were required to make a SIP amendment for 

the 2008 ozone NAAQS, the amendment would amount to a paperwork exercise and would be 

redundant as facilities in the nonattainment area are already subject to the emissions statement 

requirement. Facilities have been submitting annual emissions statements in ozone 

nonattainment areas for years. The Department is encouraged by the EPA's common sense 

approach in this area.
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Response: The EPA addresses the emission statement requirement in section III.J.2 of the SIP 

Requirements Rule. The final rule requires the emission statements or the emission statement 

certification letters to be “in the SIP”. This will require that the emission statement letters do 

need to go through the public notice and comment process. 

The EPA published guidance on source emission statements in a July 1992 memorandum titled, 

“Guidance on the Implementation of an Emission Statement Program.” A memorandum titled, 

“Emission Statement Requirements Under 8-hour Ozone NAAQS Implementation,” dated March 

14, 2006, clarified that the source emission statement requirement under the CAA was applicable 

to all areas designated nonattainment for the 1997 ozone NAAQS and classified as Marginal or 

higher under subpart 2, part D, title I of the CAA. This requirement similarly applies to all areas 

designated nonattainment for the 2008 ozone NAAQS. Most areas that need an emission 

statement program already have one in place due to a nonattainment designation for an earlier 

ozone NAAQS. If a state has a previously approved emission statement rule in force for a 

particular area for the 1997 ozone NAAQS or the 1-hour ozone NAAQS that covers all portions 

of the nonattainment area for the 2008 ozone NAAQS, such rule should be sufficient for 

purposes of the emissions statement requirement for the 2008 ozone NAAQS. The state should 

review the existing rule to ensure it is adequate and if it is, may rely on it to meet the emission 

statement requirement for the 2008 ozone NAAQS. In cases when an existing emission statement 

requirement is still adequate to meet the requirements of this rule, states can provide the rationale 

for that determination to the EPA in a written statement in the SIP to meet this requirement. 

States should identify the various requirements and how each is met by the existing emission 

statement program. In cases when an emission statement requirement is modified for any reason, 

states must submit to EPA the revisions to the emission statement as part of their SIP.

K. What are the ambient monitoring requirements?

1. Cost of monitoring programs

Commenters (0175 and 0179) proposed that, any additional monitoring requirements be fully 

funded by the EPA.

Response: The EPA notes that it has historically funded part of the cost of the installation and 

operation of monitors used to satisfy Federal monitoring requirements. The EPA understands 

these concerns, although the CAA requirements from which this proposal derives (the CAA 

sections 109, 110, 172, 181 through 185B, 301(a)(1) and (501(2)(B)) are not contingent on the 

EPA providing funding to states to assist in meeting monitoring requirements. However, the 

EPA intends to work with NACAA and the state and local air agencies in identifying available 

state and Tribal Air Grant (STAG) funds and consider the resources that may be needed to plan, 

implement, and operate the minimum requirements for the ozone monitoring network.

2. Ambient monitoring rule

Comment: Commenters (0155, 0157) stated that, while the schedule for finalizing any or all 

aspects of the ozone monitoring proposal remains unclear at this time, if and when the EPA 

requires such monitoring, states will need time, resources and training to implement the 
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requirements.

Commenter (0180) stated that, the EPA proposed lengthening the ozone monitoring seasons in 

29 states, including Wyoming. Commenter (0180) stated that, for the EPA to ignore data about 

ozone exceedances by not requiring it to be collected for places like Wyoming is to ignore an 

important aspect of the ozone problem, which is arbitrary and capricious. Therefore, Commenter 

(0180) requested the EPA to finalize the 2009 monitoring rule proposed changes. 

Commenters (0155 and 0157) stated that, while the schedule for finalizing any or all aspects of 

the ozone monitoring proposal remains unclear at this time, if and when, the EPA requires such 

monitoring, states will need time, resources and training to implement the requirements.

Commenter (0180) stated, the EPA must finalize its ambient monitoring rule and that failure to 

do so is arbitrary and capricious. Commenter (0180) asserted the proposed revisions would assist 

the EPA in implementing the 2008 ozone NAAQS. See 74 FR 34525, 34527 (July 16, 2009). 

Commenter (0180) incorporated by reference the docket in support of the EPA’s proposed 

lengthening, by 1 to 5 months, the ozone monitoring seasons in 29 states, effective January 1, 

2011. Id. at 34533-34. Commenter (0180) asserted that, to ignore data about ozone exceedances 

by not requiring it to be collected for places like Wyoming is to ignore an important aspect of the 

ozone problem, which is arbitrary and capricious. 

Response: Ozone monitoring requirements are specified in 40 CFR part 58, Appendix D, section 

4.1. Specific ozone season monitoring requirements are contained in Table D-3. These 

requirements are intended as minimum monitoring requirements, and as explained in paragraph 

4.1, “The EPA Regional Administrator and the responsible state or local air monitoring agency 

must work together to design and/or maintain the most appropriate O3 network to service the 

variety of data needs in an area.” The EPA notes that states can operate additional monitors 

beyond the minimum requirements and/or can operate ozone monitors for a longer period than 

the minimum required ozone season described in Table D-3. If such monitors are operated and 

the resulting data are acceptable quality, the EPA can use the data in support of actions that 

support the NAAQS. 

Regarding the comment that states will need time, resources and training to implement any new 

requirements, See RTC in section K.1 of this RTC.

Comment: Definition of ozone season

Commenter (0154) asserted that, the EPA uses the term "ozone season" throughout the proposal, 

but states "ozone seasons" have not been updated since October of 2006, presenting 

implementation difficulties when violations of the NAAQS occur outside of the currently defined 

ozone season. Commenter (0154) noted that, the EPA proposed revisions to the ozone 

monitoring rules in July 2009, yet 4 years have passed without a final version of the rule. Since 

the requirements of these two rules are interwoven, commenter (0154) recommended that, the 

EPA complete the two rules at the same time or remove the term "ozone season" from the 

Implementation Rule.
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Response: In the context of the proposal, the term “ozone season” has the same definition as 

“ozone monitoring season” as defined by requirements in 40 CFR part 58, Appendix D, section 

4.1. Specific ozone season monitoring requirements are contained in Table D-3. These 

requirements are intended as minimum monitoring requirements, and as explained in paragraph 

4.1, “The EPA Regional Administrator and the responsible state or local air monitoring agency 

must work together to design and/or maintain the most appropriate O3 network to service the 

variety of data needs in an area.” The EPA notes that states can operate additional monitors in 

addition to minimum requirements and/or operate ozone monitors for a longer period than the 

minimum required ozone season described in Table D-3. If such monitors are operated and the 

resulting data are of acceptable quality, the EPA can use the data in support of actions that 

support the NAAQS, and states similarly could propose control strategies that account for any 

violations that occur outside of the currently defined ozone season.

L. How can an area qualify for a 1-year attainment deadline extension?

1. Support proposal

Comment: Commenter (0159) supported the EPA’s proposal, as it is supported by statutory 

authority, and suggested that the 2-year averaging provided in section 51.1107(a)(2) also be 

applied to section 51.1107 (a)( 1) for both the first and second extension years.

Commenter (0163) agreed with using the approach set forth in 40 CFR section 51.907 for 

purposes of the 2008 ozone NAAQS. Commenter (0179) agreed with the proposal to use the 

same approach used in the 1997 ozone NAAQS Phase 1 rule, applicable to concentration-based 

standards. 

Response: The EPA appreciates the support to continue to implement the 1-year attainment 

deadline extension policy as applied previously under the 1-hour and 1997 8-hour ozone 

implementation rules. The suggestion to use a 2-year average for the first 1-year extension in 

section 51.1107 (a)(1) could result in fewer areas being eligible for a 1-year extension, even 

though such areas have already achieved the appropriate emissions reductions necessary to 

attain. The EPA does not wish to unnecessarily restrict eligibility for such areas, and is finalizing 

the 1-year attainment deadline extension policy as proposed.

M. How will the EPA address transport of ozone and its precursors for rural nonattainment 

areas, multi-state nonattainment areas and international transport?

1. Rural areas

Comment: Support for the approach to rural transport

Commenter (0159) supported the broad use of rural transport. The Commenter stated that, the 

EPA proposed to interpret language so that, to qualify for a rural transport classification, the 

nonattainment area's boundary could not include or be adjacent to an MSA, based on the Census 

Bureau's latest population estimates. Id. Under such an approach, any nonattainment area 
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associated with a census-defined micropolitan area or area too sparsely populated to be included 

in a census-defined statistical area, based on Census Bureau population estimates, may be able to 

qualify for a rural transport classification. Its usage would retain Marginal permitting 

requirements, but, for instance, would prevent an urban upwind problem from causing a 

downstream rural area to be forced to implement emission reduction and to be subject to more 

stringent permitting. (0159)

Response: The EPA appreciates the commenter’s support. The EPA believes this interpretation 

of the CAA section 182(h) is consistent with the original scope of section 182(h) as promulgated 

in 1990 and provides maximum flexibility for areas to qualify for this classification where 

appropriate.

2. Methane as a Precursor

Comment: Support position not to regulate methane

Commenter (0151) supported the EPA’s position not to regulate methane under this program. 

The Commenter stated that, the EPA solicited comment on regulating methane as an ozone 

precursor because reportedly the European Union controls it for ozone reductions. Id. 34205. 

Methane was originally excluded by the EPA as a negligibly reactive compound under the 

agency’s ozone reactivity policy and California’s historic Rule 66 for the regulation of 

hydrocarbons. Then it was determined to have some reactivity under the 1977 Reactivity Policy 

when compared with ethane, until it was once again excluded by rulemaking following extensive 

testing and evaluation on the basis of its photochemical oxidation potential on a molar and mass 

basis. Whatever the Europeans’ motive for regulating methane as a VOC, there is little scientific 

justification for regulating methane as an ozone-precursor. 

Response: The EPA appreciates the support from the commenter. Methane has not been 

addressed as part of ozone attainment planning in the past because of the limited effect that local 

measures to control methane would have on local or regional ozone concentrations in the 

immediate time frame. Given the temporal and spatial characteristics associated with methane 

and ozone, we continue to believe that it is inappropriate to require or rely on local methane 

emission reductions in ozone SIPs.

3. International transport

Comment: Support consideration of emissions from North American or intercontinental 

sources

Commenter (0132) stated that, they support the EPA's interpretation of the CAA § 179B to 

include consideration of any emissions from North American or intercontinental sources. The 

commenter stated that, the EPA's interpretation that, the CAA, §179B could include 

consideration of any emissions from any non-U.S. sources is appropriate. The TCEQ endorses 

this interpretation since it accounts for the potentially significant impact that international 

emissions can have on an area's air quality. The TCEQ seeks confirmation of the interpretation 
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that FCAA, § 179B may be applied to nonattainment areas other than those adjoining 

international borders. Further, the TCEQ seeks confirmation that "emissions emanating from 

outside the U.S. FCAA, §179B include anthropogenic sources and natural emission sources 

outside the continental U.S. EPA did not provide an explanation for why it proposed limiting the 

availability of a determination under FCAA, §179B to areas classified "Moderate" or above, 

excluding "Marginal" areas. Since FCAA, §179B does not limit this option to areas classified 

"Moderate" or above, the TCEQ supports its availability for all areas, including "Marginal"

areas. Commenter (0159) generally supported the EPA 's promise to continue to work with its 

domestic and international partners to better understand the extent and implications of 

transboundary flows of air pollutants and where possible, to mitigate their impact on our 

domestic air quality.

Commenter (0159) supported the EPA’s proposal to find that, if it approves a "but for" 

demonstration for an area, the area would not be subject to reclassification for failure to attain by 

its attainment deadline, and if such areas were classified as Severe or Extreme, the section 185 

fee program would not apply based on a failure to attain by the attainment date; Commenter 

(0159) agreed that, a nonattainment area should not be penalized by the actions of others which 

are outside of such area’s control.

Commenter (0159) supported the EPA’s proposal that, where international transport meets the 

criteria contained in the EPA's EER (40 CFR § 50.14), it can be addressed by that rule. 

Commenter (0159) supported a reasonable interpretation of the EER, as "exceptional events" are 

truly exceptional occurrences that are beyond an affected area's control and such events should 

be excluded when they occur.

Response: The EPA appreciates the commenter’s support. The EPA has interpreted the Act such 

that section 179B allows the EPA to approve an attainment demonstration if the state can 

satisfactorily demonstrate that ‘‘but for emissions emanating from outside of the U. S.,’’ the area 

would attain and maintain the ozone standard. The EPA has historically evaluated these 

demonstrations on a case-by-case basis, based on the individual circumstances, which may 

include areas not adjoining international borders, the classification of the area and the data 

submitted by the state. Also, in the proposal, EPA did not intend to give the impression that 

section 179B did not apply to all nonattainment areas. Since Marginal areas are not required to 

submit an attainment demonstration, the proposal indicated that for areas classified as Moderate 

and above, the modeling and other elements of the attainment demonstration must show timely 

attainment of the NAAQS but for the emissions from outside of the U.S. However, if a Marginal 

area were to submit to the EPA a demonstration that they could attain the standard but for 

international emissions, the EPA would be able to evaluate that demonstration similarly to 

demonstrations submitted for higher classified areas.

Comment: Make available international transport information

Commenter (0173) requested the EPA to take additional steps to facilitate state submissions. The 

Commenter stated that, where the EPA has already determined that international emissions 

increased U.S. ozone levels by a particular quantity or in a range of quantities, the EPA should 

publicize that quantification and allow states to rely on it in making section 179B 
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demonstrations. As the statute only requires the quantification to be "establishe[d] to the 

satisfaction of the Administrator," there would be no purpose in requiring states to duplicate 

evaluations that the EPA may have already made. In addition, the EPA should make available 

other information it has on evaluating transboundary ozone impacts and provide an electronic 

clearinghouse for use in states' demonstrations under section 179B. (0173)

Response: The EPA considers international transport of pollution an important issue. Given the 

challenge and complexity of assessing the potential impacts of international emissions on air 

quality in the U.S., the EPA has been engaged in a number of activities to improve our 

understanding of such transport. For example, the agency is actively participating in the Task 

Force on Hemispheric Transport of Air Pollution (HTAP) which is an international effort to 

assess intercontinental air pollution transport and to look for opportunities to mitigate its impact. 

While HTAP and other related analytical efforts can help improve the general characterization of 

the impacts of international emissions on U.S. air quality, the EPA has no plans to conduct 

determinations with the local specificity that would be required of a 179B demonstration which 

show that a specific locality would have attained over a specific time period “but for” the 

contribution of international emissions. We will continue to work with states that are developing 

plans pursuant to section 179B to ensure the states have the benefit of the EPA’s developing 

understanding of the general nature of international transport of ozone and its precursors. 

However, the EPA continues to believe that the best approach for addressing international 

transport is to work on a case-by-case basis to develop international impact quantification 

analyses that are suited to the unique situation of each area.

4. Interstate transport requirements

Comment: Quantify interstate transport obligations

Commenter (0170) stated that, the EPA must quantify the states’ interstate transport obligations 

for the 2008 ozone NAAQS as expeditiously as possible. The Commenter indicated that, the 

states were statutorily required to submit infrastructure SIPs for the 2008 ozone NAAQS by 

March 12, 2011. 78 FR 34,178, 34,182 (June 6, 2013). As the EPA notes in its proposal, this date 

“remained the legally applicable deadline for infrastructure SIPs” despite the reconsideration 

process the EPA undertook for the 2008 ozone NAAQS. Id. at 34,183. However, many states 

failed to meet the SIP deadline. On January 15, 2013, the EPA found that 28 states, the D.C. and 

the Commonwealth of Puerto Rico failed to submit infrastructure SIPs containing the CAA 

requirements necessary to implement the 2008 ozone NAAQS. 78 FR 2882 (Jan. 15, 2013). The 

Commenter added that, among other things, states must include provisions in their SIPs that 

satisfy the interstate transport requirements of the CAA, commonly known as “good neighbor” 

obligations. See 42 U.S.C. § 7410(a)(2)(D)(i)(I). In EME Homer City, the D.C. Circuit held that 

the EPA must “define or quantify” the states’ interstate transport obligations before the EPA can 

require the states to incorporate those obligations into their SIPs. See EME Homer City 

Generation L.P. v. EPA, 696 F.3d 7, 31 (D.C. Cir. 2012).2 Furthermore, “once the EPA defines 

or quantifies a state’s good neighbor obligation, the state must have a reasonable time to 

implement that requirement with respect to sources within the state.” Id. (emphasis added). The 

commenter indicated that the D.C. Circuit’s instruction in EME Homer City is clear: the EPA 
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must “define or quantify” states’ good neighbor obligations and give states “a reasonable time” 

to implement those requirements. See 696 F.3d at 38. States have an equally clear mandate and 

deadline under section 110(a) of the CAA: each state shall, within 3 years after promulgation of 

a NAAQS, submit a SIP to the Administrator that shall contain adequate provisions to address 

the state’s good neighbor obligations under section 110(a)(2)(D)(i)(I). See 42 U.S.C. § 7410(a). 

Lastly, the D.C. Circuit, in North Carolina v. EPA, mandated that upwind states’ good neighbor 

obligations must be harmonized with the NAAQS attainment deadlines for downwind states. See 

531 F.3d 896, 912 (D.C. Cir. 2008). (0170)

The Commenter concluded, in order for the states to meet their section 110(a) SIP submission 

deadlines, the EPA must “define or quantify” the states’ good neighbor obligations a “reasonable 

time” before the section 110(a) deadline arises for each NAAQS. But despite this clear directive, 

and despite the fact that the SIP deadline for the 2008 ozone NAAQS came and went over 2 

years ago, the EPA’s proposed implementation rule for the 2008 ozone NAAQS “does not 

address states’ obligations under the [CAA] to reduce transported pollution.” 78 FR at 34,183. 

Moreover, the EPA does not even plan to provide guidance “on how to meet the requirements of 

section 110(a)(2)(D)(i)(I)” in a forthcoming guidance memorandum laying out infrastructure SIP 

requirements for the 2008 ozone NAAQS. Id. (0170)

The Commenter believed that, the EPA’s decision not to quantify the states’ good neighbor 

obligations, or even provide guidance to the states, cannot be reconciled with the clear mandate 

established in EME Homer City. Indeed, the EPA does not attempt to justify its decision. Given 

the urgent need for the EPA to address the continuing problem of interstate air pollution, this 

delay is particularly unjustified. Therefore, we respectfully urge the EPA to comply with its 

mandatory obligation under the D.C. Circuit’s decision in EME Homer City and “define or 

quantify” the states’ good neighbor obligations with respect to the 2008 ozone NAAQS as 

expeditiously as possible.

Commenter (0177) stated that, the proposed rule does not address states’ good neighbor 

responsibilities under the CAA section 110(a)(2)(D)(i)(I) concerning upwind emissions that 

significantly contribute to ozone nonattainment or interfere with maintenance in downwind 

states. The commenter supports the EPA’s current efforts before the U.S. Supreme Court to 

clarify the legal framework necessary to address interstate air pollution, but reminds the EPA 

that both CAIR and the CSAPR were directed at meeting the 1997 ozone NAAQS. As such, a 

separate transport rule is needed as soon as possible to begin to address the 2008 ozone NAAQS. 

The transport rule will help solve the transport problem; however, it does not eliminate each 

state’s responsibility to address transport under the good neighbor provisions of the CAA. The 

Commenter stated that, the Connecticut Department of Energy and Environmental Protection 

routinely measures ozone levels at Connecticut’s upwind boundaries that violate the 2008 

NAAQS. The EPA and other available modeling provide substantial evidence that Connecticut 

cannot comply with the 2008 ozone NAAQS without additional large-scale reductions in upwind 

ozone precursor emissions. At a minimum, the EPA should adopt a suite of new stringent 

national rules addressing mobile sources, EGU (including a focus on periods of high electric 

demand), and industrial/commercial boilers--which would be the most cost effective and legally 

defensible manner to achieve attainment with the 2008 ozone NAAQS as expeditiously as 
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practicable.

Commenter (0157) encouraged the EPA to move expeditiously to "define or quantify" upwind 

states' good neighbor obligations in order that upwind states may meet their section 110(a) 

infrastructure SIP obligations and downwind states may meet their attainment deadlines. The 

Commenter added that, controlling transported air pollution is key to Maryland attaining the 

ozone NAAQS and the fact that transport becomes central to attainment with every lowering of 

the NAAQS. Specifically, with every decrease in the NAAQS, the proportion of the NAAQS 

represented by transported pollution in states increases. (0157)

Commenter (0152) noted that, the EPA is not addressing the CAA section 110(a)(2)(D)(i)(I) 

provisions and believed states should not be required to meet them. The commenter directed 

attention to the D.C. Circuit's EME Homer City Generation v EPA decision (696 F.3d 7 (D.C. 

Cir. 2012)) that concluded that a SIP cannot be deemed incomplete or deficient for failure to 

meet this obligation until such time that the EPA quantifies the state's obligation under this 

provision. 

Response: On April 29, 2014, the Supreme Court issued a decision reversing the D.C. Circuit’s 

decision in EPA v. EME Homer City Generation Co., No. 12-1182. The Supreme Court held that 

the CAA does not require that the EPA give states a second opportunity to submit interstate 

transport SIPs after the EPA has quantified a state’s obligation to eliminate its significant 

contribution to interstate transport. For all states, the Supreme Court decision means that each 

state has an obligation to develop interstate transport SIPs addressing the CAA section 

110(a)(2)(D)(i)(I) requirements without an EPA rulemaking as a prerequisite. The Supreme 

Court decision clarifies that the deadline for submitting transport SIPs is 3 years from the 

promulgation of the NAAQS. The EPA is still reviewing the implications of the Supreme Court 

decision on the SIP process. The EPA agrees that to date, the EPA has not provided guidance to 

states substantively addressing CAA section 110(a)(2)(D)(i)(I) requirements for the 2008 ozone 

NAAQS.

Comment: Large nonattainment area concept

Two states (0157 and 0168) commented that, for their areas to achieve attainment would require 

reductions in transported emissions from other states. They pointed out that the EPA has 

previously determined that emissions from certain upwind states are significantly impacting their 

state’s air quality. They believe that the boundaries for the designated nonattainment areas do not 

reflect the scope of the problem. One Commenter (0157) believes that, a tool in the CAA that the 

EPA can use to assist with attaining the current and pending lower ozone standards is the ability 

to create large, regional nonattainment areas. 

Response: The issue of appropriate nonattainment area boundaries for the 2008 ozone NAAQS 

or any future revised ozone NAAQS is beyond the scope of this current rulemaking. The EPA 

completed the initial designations for the 2008 ozone NAAQS in the spring of 2012. The basis 

for the nonattainment boundaries are provided in the Technical Support Documents for the areas, 

which are available in the docket for the designations at EPA-HQ-OAR-2008-0476. In addition, 
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in the RTC document for the designations, also available in that docket, the EPA provided 

responses to Commenters who urged the EPA to establish large nonattainment areas.

Comment: Delaware air quality

Commenter (0168) stated that, this rule will not make Delaware's air quality better, may likely 

make Delaware's air quality worse and will increase the burden on Delaware. The Commenter 

stated that, the EPA designated 474 counties as not meeting the 1997 0.08 ppm ozone standards 

and 232 counties as not meeting the more protective 2008 standards. This shows that air quality 

continues to improve across the nation as a result of successful federal, state and local pollution 

reduction efforts. However, this is also cause for significant concern to Delaware because 1) the 

control requirements of this proposed rule are being applied to a smaller area which has already 

been through several rounds of similar requirements and 2) this proposed rule revokes the 1997 

ozone NAAQS, and proposes anti-backsliding requirements that are keyed to local air quality 

without consideration to impact on downwind areas like Delaware. (0168)

 Less of the states that are causing Delaware's unhealthy air will be covered by this 

implementation rule than by past implementation rules—this is contrary to the 

language of the CAA and will continue to impede progress towards its goal of healthy 

air quality. (0168)

 Given all non-trivial Delaware sources are currently well-controlled implementation 

of this rule will be a significant administrative burden on Delaware with no resultant 

air quality benefit. Application of the rule to a smaller upwind area that has 

previously been covered by similar rules is also not likely to help Delaware's air 

quality. (0168)

 This proposed rule revokes the 1997 ozone NAAQS, and proposes anti-backsliding 

requirements that appear to be keyed to local air quality only; without consideration 

to impact on downwind areas like Delaware. (0168)

 Delaware's main concern is that areas that were designated as nonattainment for the 

1997 NAAQS may not be required to develop and be bound by maintenance plans, 

and may be able to relax SIP requirements under the CAA 110(l) without 

consideration to downwind impacts. (0168)

 Delaware's attainment of the ozone NAAQS is outside of its control due to the 

overwhelming impact of upwind emissions; and there appears to be no mechanism in 

place to mitigate these upwind emissions in the timing of the CAA and EPA proposal. 

(0168) 

The Commenter believed Delaware is being penalized for circumstances that are beyond its 

control, and a voluntary or mandatory bump-up is not the answer. The EPA recognizes in the 

proposed rule that in many areas transport is the problem--and that the EPA’s main goals with 

this proposed implementation rule are to provide flexibility, increase implementation efficiency, 

allow the most effective pollution control programs to be implemented and identify additional 

ways in which the EPA can assist the states to reach attainment within the legal framework of the 

CAA; all without jeopardizing expeditious attainment of the public health and welfare goals. To 
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achieve these goals, the EPA must require the control of all of the emissions that are causing the 

problem. 

Response: The EPA recognizes that many states are affected by transported ozone and ozone 

precursors from upwind states and that transported pollution may contribute significantly to air 

pollution that exceeds the NAAQS in those states. The CAA establishes states’ responsibilities to 

address interstate transport through two provisions. First, section 110(a)(2)(D)(i) obligates states 

to include provisions in their infrastructure SIPs to prohibit any source or other type of emissions 

activity in one state from contributing significantly to nonattainment, or interfering with 

maintenance, of the NAAQS in another state, from interfering with required provisions 

preventing significant deterioration of air quality or from interfering with measures to protect 

visibility in another state. Second, section 126 directs states to include provisions to establish a 

notification process in their infrastructure SIPs through which downwind jurisdictions can be 

alerted to specific sources of transported pollution. The EPA issued its “Guidance on 

Infrastructure SIP Elements Under the CAA sections 110(a)(1) and 110(a)(2),” on September 13, 

2013,25 on the required elements of the section 110 infrastructure SIP submittal for the 2008 

ozone NAAQS. This guidance does not, however, address the requirements of the CAA section 

110(a)(2)(D)(i). The final rule, does not address these requirements relating to transport for 

purposes of the 2008 ozone NAAQS. The EPA will address the transport requirements for the 

2008 ozone NAAQS in a separate action.

N. How will the section 182(f) NOX provisions be handled?

Comment: Commenter (0163) stated, the EPA must take care to implement the CAA section 

182(f) provision consistent with other related provisions; e.g., the EPA should avoid granting 

NOx exemptions for nonattainment areas that use NOx controls from other programs to 

demonstrate attainment and/or to address other provisions of the CAA (i.e., CAA section 

110(a)(2)(D)(i)(I)).

Response: In order to request a NOx exemption, a state must submit a SIP revision specific to 

the 2008 ozone NAAQS. This SIP revision must specifically address the provisions of section 

182(f). The EPA will grant NOx exemptions only through notice and comment rulemaking where 

Commenters will have an opportunity to address whether the SIP revision complies with the 

provisions of section 182(f). In granting waivers, the EPA will take into consideration existing 

NOx controls in an area. 

O. Emissions Reduction Benefits of Energy Efficiency/Renewable Energy Policies and 

Programs, Land Use Planning and Travel Efficiency

1. Energy efficiency/renewable energy policies and programs

 

25 See http://www.epa.gov/oar/urbanair/sipstatus/infrastructure.html.
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Comment: Clarify inclusion of EE/RE programs in attainment plans

Commenter (0130) stated that, the EPA should clarify how inclusion of EE/RE programs in an 

attainment plan is supportable by the various requirements for attainment plans in the CAA. The 

Commenter argued that, should this be done under the RACT or RACM requirements of the 

CAA? If so, how might a state calculate the cost per ton reduced of such strategies? The length 

of time needed to implement such strategies is significant, and many years will pass before 

enough EE/RE programs have reduced emissions significantly enough for air quality modeling to 

show a definable benefit. Therefore, such programs would not fit under either the RACT 

requirements, which must be implemented by January 1, 2017, or the RACM requirements, 

which must show that the attainment date may be advanced by 1 year. The preamble seems to 

indicate that EE/RE policies may be implemented to mitigate the transport of ozone precursors to 

downwind states. However, no analysis appears to be included in this preamble that shows how 

such policies might affect transport or a state's significant contribution to a downwind state.

The Commenter added that, while EE/RE policies are sound for many reasons, not the least of 

which is reducing dependence on foreign energy sources, the EPA should clarify how inclusion 

of these programs in an attainment plan is supportable by the various requirements for attainment 

plans in the CAA. Without further clarification in the preamble, to require or even suggest states 

somehow analyze whether an attainment SIP should include the implementation of additional 

EE/RE programs for RACT, RACM or section 110(a)(2)(D) transport initiatives will only add a 

paperwork burden to states developing the attainment plans.

Response: The inclusion of EE/RE policies and programs into an attainment plan is not a 

requirement, but rather, an optional approach that allows states to include flexible and innovative 

non-traditional strategies that have the potential to make small, but meaningful, contributions to 

attainment. EE/RE can help reduce electricity generation from fossil-fueled sources, which leads 

to lower emissions of NOx and other pollutants. The reduction in emissions can benefit a 

particular area, and can also have a positive impact on downwind areas affected by ozone 

transport.

The EPA, with the EE/RE Roadmap (http://epa.gov/airquality/eere/), has clarified how EE/RE 

policies and programs can be included into a SIP. No new regulations have been introduced. 

Since the application of EE/RE will be specific to a given area, we encourage states to work 

closely with their EPA Regional Offices should they need assistance with incorporating EE/RE 

into their attainment plans.

Recognizing the need for more certainty and capacity-building on EE/RE, the EPA offers 

additional assistance to states, tribes and local agencies, including technical assistance, energy 

savings information, and tools, such as AVERT, the AVoided Emissions and geneRation Tool 

(www.epa.gov/avert), to quantify the emissions impacts of EE/RE policies and programs. The 

EPA is working with several states to document how specific EE/RE policies and programs 

could be quantified and included in SIPs, and will share these examples.
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Comment: Support for Innovative and Creative Approaches

Commenters (0129 and 0158) supported the EPA’s proposal to continue to allow states to 

integrate into their SIPs the emission reduction benefits of energy efficiency and renewable 

policies and programs. Commenter (0158) stated, the final rule and EE Roadmap should also 

recognize energy savings achieved through grid-side efficiency technology 

improvements/upgrades and clarify that such programs may also be considered by states for 

integration into their SIPs.

Response: The EPA appreciates the support expressed for innovative approaches to reducing 

emissions, such as EE/RE policies and programs. We note, however, that the EPA’s EE/RE 

Roadmap focuses on the potential use of EE/RE for attainment planning purposes. Under the 

CAA, the RACT requirements are separate from attainment planning requirements. 

The EPA by no means discourages grid-side efficiency technologies, but reminds the 

Commenter that, the state has the responsibility for including these types of programs in a SIP. A 

good first step would be to discuss these programs with the state energy and air offices.

Comment: Support for EE/RE Measures

Commenters (0159 and 0179) supported the EPA's position to encourage states to consider 

adopting EE/RE policies and programs to benefit nonattainment areas in their own state, as well 

as to reduce the impact of ozone transport on downwind states. Commenter (0179) indicated that, 

significant uncertainty still remains on the availability of energy models required to perform the 

certain SIP demonstrations and requested that the EPA approve regional models that have been 

submitted for such purposes. Commenter (0179) also requested that, the EPA provide assistance 

and resources to generate SMOKE ready output such that air quality impacts of electricity offsets 

in nonattainment areas and surrounding areas/states can be modeled and used appropriately in a 

SIP.

Response: The EPA appreciates the support expressed for EE/RE policies and programs that can 

benefit overall air quality. The EPA is working with several states to document how specific 

EE/RE policies and programs could be quantified and incorporated into SIPs.

The EPA has recognized that the most-sophisticated approach to emission quantification is 

energy modeling, which relies on resource-intensive energy models. Because all states do not 

have this capacity, the EPA has developed a free tool, AVERT (www.epa.gov/avert), based on 

reported hourly emissions. AVERT is designed to be used by state air quality planners, and will 

produce SMOKE-ready outputs.

2. Land use planning

Comment: Commenter (0130) stated that, inclusion of land use planning strategies in a SIP 

oversteps the bounds of state authority and recommended that the EPA clarify that a state is not 

required to analyze land use planning strategies in any attainment plan. The Commenter stated 
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that, land use planning is the purview of local government jurisdictions in the Commonwealth. 

Inclusion of such strategies in a SIP oversteps the bounds of state authority. Additionally, land 

use planning offers very few opportunities for near term (2020 or sooner) emission reductions 

since such plans take many years to influence the commuter traffic patterns. Therefore, it is 

unclear under what section of an attainment plan would the EPA suggest land use planning be 

included. For example, such strategies would not be appropriate for inclusion in RACT or 

RACM analyses. The Commenter suggested that, the EPA should clarify how they expect a state 

to utilize the CAA to require or regulate land use planning. DEQ also recommends that the EPA 

should clarify that a state is not required to analyze land use planning strategies in any attainment 

plan. Should a state have the authority to do so, and should that state believe land use planning is 

a cost effective means to attaining the 2008 ozone standard by the attainment date, then they may 

include land use planning strategies within their SIP, perhaps as a part of some sort of voluntary 

bundle. The current preamble, however, indicates that all attainment plans should at least analyze 

this option. Requiring the analysis of land use planning in all SIPs will only add paperwork to an 

already paperwork-intensive process. (0130)

Commenter (0156) stated that, while land use changes might not easily fit into the time period of 

SIP control requirements, they appreciated the EPA efforts to allow for SIP emission credits for 

innovative options including land use and travel efficiencies.

Commenter (0159) agreed with measures, such as land use planning, that credit states when they 

work to reduce such emissions, as mobile emissions are a large contributor to the formation of 

ozone.

Response: States should consider all potentially available measures, including land use strategies 

in the RACM element of the SIP. A detailed analysis of emissions impacts of land use planning 

is not a requirement for determining RACM. However, due to the potential for land use policies 

to reduce travel activity, the EPA encourages consideration of land use planning in the RACM 

determination. In many cases, such as those identified by the Commenter, a simple assessment 

and reasoned explanation would be sufficient for eliminating land use planning from further 

detailed analysis. If a state provides evidence that land use planning is not economically and 

technologically feasible or will not advance the attainment date, the state may eliminate it as a 

potential emission reduction strategy. However, lack of state authority, by itself, is not sufficient 

grounds for failure to consider land use planning or any other potential SIP strategy. Some states 

do have authority for land use planning and others can explore ways to gain the authority. 

Alternatively, states can work cooperatively with local jurisdictions that do have authority, to 

include land use planning commitments in the SIP.

3. Travel efficiency

Comment: Commenter (0130) stated that, the EPA should note that conducting an 

analysis of this “low cost” bundle is optional for states to include in any attainment plan 

(78 FR 34207). The Commenter added that, the EPA does not clarify under what section 

of the CAA these strategies should be considered for implementation. Will these 

strategies be part of an area's RACM analysis? Or some sort of voluntary bundle? If the 
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EPA's intent is to require an evaluation of the “low cost” bundle of measures in the 

attainment planning process, then DEQ strongly recommends that the EPA specifically 

note how states should approach the implementation of these strategies. The Commenter 

suggested that, the EPA should note that conducting an analysis of this "low cost" bundle 

is optional for states to include in any attainment plan. Many of these so-called “low 

cost” bundles are actually quite expensive. For example, retrofitting trucks with APUs 

costs approximately $7,000 to $9,000 per truck retrofitted, according to readily available 

information. To make this an effective control strategy for NOx, a significant number of 

vehicles will need to be retrofitted. Where will the money come from to fund these 

retrofits? Higher parking rates, taxes on free private parking, parking permits, congestion 

pricing and intercity tolls will all have someone paying more money, will require that 

jurisdictions raise taxes on its citizenry and will be quite controversial in a time when 

gasoline and diesel are expensive. In many ways, these are not "low cost" initiatives. 

Therefore, the EPA should clearly note that any consideration of the strategies in the 

“low cost” bundle or any other strategy within the “Moving Cooler” report is optional in 

the development of an area's attainment plan.

Response: States should consider all potentially available measures, including travel 

efficiency strategies in the RACM element of the SIP. The EPA does not require an 

analysis specifically of the Moving Cooler report’s “low cost bundle” strategies 

referenced in the proposed rule. However, the EPA recognizes the potential for travel 

efficiency policies to reduce travel activity and encourages consideration of them in the 

RACM determination. The EPA is suggesting that the low cost bundle may be the most 

appropriate for consideration among the six different bundles included in the referenced 

report. The strategies included in the report range greatly in stringency, cost and 

difficulty of implementation. The low cost bundle represents those strategies that may be 

easiest to achieve among them. In many cases, such as those identified by the 

Commenter, a simple assessment and reasoned explanation would be sufficient for 

eliminating some travel efficiency strategies from further detailed analysis. If a state 

provides evidence that a travel efficiency strategy is not economically and 

technologically feasible or will not advance the attainment date, the state may eliminate it 
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as a potential emission reduction strategy. 

Comment: Land use travel efficiency

Commenter (0156) concurred with the EPA that, land use travel efficiency reduction options 

may not fit easily into the timelines of the CAA or the EPA's traditional expectations for SIPs 

(page 34180). 26

Commenter (0156) believed the 2-5 percent emission reductions from land use and travel 

efficiencies mentioned on page 34207 are not achievable and would not want this to contribute to 

unrealistic expectations during SIP development. 

The 2-5 percent reduction is based upon forecasted emission reductions between 2010 

and 2020. A more realistic time-period would be 5 years, the interval between when the 

 

26 “Potential Changes in Emissions Due to Improvements in Travel Efficiency - Final Report, 

EPA, March 2011" suggests a maximum of 2 percent in combined NOx and VOC emission 

reductions could occur over a 5-year period. This EPA study discloses that the bundle of: travel 

demand management (TOM) + land use changes + transit fare reduction + transit service 

improvements + parking fees + mileage fees "bundle" may reduce CO2 by 8.83 percent PM by 

8.78 percent, NOx by 8.65 percent and VOCs by 8.29 percent by the year 2050 (40 year 

reduction). On average, a 0.2 percent emission reduction per pollutant per year could be achieved 

if implementing all bundled measures.
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SIP is due in 2015 and the EPA selected out-year of 2020. In addition, the 2-5 percent 

reduction was based upon some assumptions used in the Moving Cooler Report that does 

not produce results upon which decision-makers can rely. While Moving Cooler had 

some valid findings and virtually all the strategies in the report have merit at some level, 

many strategies were formulated beyond what can be reasonably achieved, according to 

comments provided by the American Association of State Highway and Transportation 

Officials (AASHTO), Federal Highway Administration (FHWA) and state Departments 

of Transportation (DOTs). Unless the nature of the strategies in the report are fully 

understood, this report may be relied on at face value to develop policies and programs 

that could have adverse and unintended consequences for our nation's transportation 

system, economy and quality of life. Some examples of unrealistic assumptions and 

questionable findings from the Moving Cooler Report include: 

 $5.00/gallon gas tax (the gas tax was $0.01 during its inception in 1932, and the 

current gas tax is only $0.184 gallon tax, and the average state combined federal and 

state tax is $0.475 cents/gallon);

 Impose a toll of 5 cents per mile on the entire interstate highway system; 

 Trips made by bicycle in the U.S. will increase from 0.4 percent today to 11 percent;

 90 percent of future development will take place in urban areas, compared to 34 

percent today;

 $400 residential parking permits would be required for on-street parking;

 Tolls would be charged to motorists who enter Central Business Districts for all 

metropolitan areas of 50,000 and above; and

 The analysis of induced demand with respect to highway-related travel was more 

challenging than the report indicates, and in the end the model used may not have 

been fully capable of addressing this issue.

Commenter (0156) stated that, while land use changes might not easily fit into the time period of 

SIP control requirements, they appreciated the EPA efforts to allow for SIP emission credits for 

innovative options including land use and travel efficiencies.

Commenter (0159) agreed with measures, such as travel efficiencies, that credit states when they 

work to reduce such emissions, as mobile emissions are a large contributor to the formation of 

ozone.

Response: States should consider all potentially available measures, including travel efficiency 

strategies in the RACM element of the SIP. Some states have included variations of these types 

of strategies in their SIPs when needed to support emission reductions necessary to meet their 

CAA requirements. The degree of stringency for these strategies depends on the needs specific to 

their air quality requirements and goals. In many cases, such as those identified by the 

Commenter, a simple assessment and reasoned explanation would be sufficient for eliminating 

some travel efficiency strategies from further analysis. If a state provides evidence that a travel 
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efficiency strategy is not economically and technologically feasible, or will not advance the 

attainment date, the state may eliminate it as a potential emission reduction strategy. 

Comment: Congestion Mitigation and Air Quality (CMAQ) for 2008 ozone maintenance 

areas 

Commenter (0130) stated that, upon revocation of the 1997 ozone NAAQS, the EPA should 

work with Federal Highway Administration (FHWA), to ensure that areas previously designated 

nonattainment or maintenance for the 1997 ozone NAAQS but attainment for the 2008 ozone 

NAAQS have access to CMAQ funding. The Commenter also stated that, without CMAQ 

funding, these important programs may need to be cut back or discontinued. The EPA, in 

conjunction with the FHWA, should consider the effect of the revocation of the 1997 ozone 

NAAQS on potential future year CMAQ fund allocations for areas that were designated 

nonattainment or maintenance under the 1997 ozone NAAQS but are designated attainment 

under the 2008 ozone NAAQS. The Commenter added that, CMAQ funding is an integral part of 

jurisdictions' transportation plans. This funding supports many travel demand management 

programs as well as multi-modal projects that provide significant emission reductions of ozone 

precursors. As such, DEQ believes that the EPA must work with FHWA to ensure that former 

nonattainment and maintenance areas continue to remain eligible to receive CMAQ funding into 

the future. Continued CMAQ funding is especially important to these areas since the EPA is 

currently re-evaluating the level of the 8-hour ozone standard and may recommend lowering it 

even further in the coming year. If such areas cannot continue to receive CMAQ funds, the EPA 

should work with FHWA to ensure that jurisdictions are eligible to receive allotments for at least 

3 to 5 years into the future. This transitional period would allow metropolitan planning 

organizations time to determine which projects and programs must be continued and to 

determine alternate funding sources. These decisions will be very difficult to make. The 

Commenter indicated several areas in Virginia that were designated attainment for the 2008 

ozone NAAQS use CMAQ funding for a variety of very successful travel demand management 

programs, such as Richmond Ridefinders, Greater Richmond Transit Company, and 

Fredericksburg's GWRideConnect. The Commenter further indicated that, CMAQ funding has 

also been successfully used to help jumpstart such multi-modal projects as the 64 Barge Express, 

which reduces truck traffic by an estimated 24,000 trips annually along the 1-64 and 1-95 

corridor between the Ports of Hampton Roads and the Port of Richmond. These programs, and 

many others like them are highly beneficial to air quality. They improve the lives of all citizens 

of the Commonwealth and improve highway safety. The Commenter believed that, continued 

CMAQ funding is essential for the RAPCA area to maintain attainment of the 1997 ozone 

standard and to possibly avoid designation of nonattainment for the 2008 standard. With funding 

being cut annually on every front—local, state and federal, the continuation of CMAQ funding is 

important. (0141)

Response: The EPA recognizes the role CMAQ funding has in supporting transportation 

projects that reduce travel activity and their associated emissions. The CMAQ funding and 

eligibility requirements are specified in the Moving Ahead for Progress in the 21st Century Act 

(MAP-21). The CMAQ program is administered by the U.S. DOT and is not subject to this 
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rulemaking. Past and current program policy and flexibility has supported continued funding for 

formerly eligible nonattainment and maintenance areas.

Comment: CMAQ funding for PM2.5 areas 

Commenter (0130) stated that, the EPA should work with FHWA to remove requirements 

mandating that areas designated as nonattainment or maintenance for PM2.5 receive additional 

funding from CMAQ. The Commenter stated that, this type of decision should be at a state's 

discretion so that CMAQ allocation processes may avoid absurd results. In Virginia, only the 

Northern Virginia area is designated nonattainment for PM2.5. Northern Virginia is part of the 

metropolitan Washington, D.C. area, which was designated nonattainment for the 1997 PM2.5 

NAAQS. Virginia has recently submitted a redesignation request and maintenance plan to 

redesignate the area to attainment/maintenance. The area's annual design values for PM2.5 using 

2010-2012 data is 10.8 μg/m3, 1.21 Jg/m3less than the 2012 PM2.5 NAAQS of 12.0 μg/m3. The 

area's 24-hour design value for PM2.5 using 2010-2012 data is 27 μg/m3, 8 μg/m3less than the 

2006 PM2.5 NAAQS of 35 μg/m3. The area was designated attainment for the 2006 PM2.5

NAAQS and is expected to be designated attainment for the 2012 PM2.5 NAAQS. Clearly, this 

area is not a persistent nonattainment area for PM2.5, however, it is a persistent nonattainment 

area for ozone. Additionally, several other areas in Virginia that currently receive CMAQ funds 

that were designated as attainment areas for the 2008 ozone NAAQS are just under the 2008 

ozone NAAQS. It makes no sense to divert CMAQ funds from these areas to metropolitan 

Washington D.C. based on the nonattainment status of the D.C. area for the 1997 PM2.5 NAAQS. 

The Commenter believed that, it made no sense to require the D.C. area to spend a percentage of 

its CMAQ funds on any type of particulate reduction strategy. The citizens in this area are 

already experiencing healthy PM2.5 air quality. What the area needs are NOx reductions for ozone 

air quality improvement. The Commenter recommended that, the EPA should work with FHWA 

to review these types of requirements for CMAQ and make necessary changes so that states have 

the flexibility to use CMAQ money for reductions most needed for improving air quality. (0130)

Response: Any state that has a PM2.5 nonattainment or maintenance area-including those with 

approved SIPs that identify on-road mobile sources as insignificant for regional transportation 

conformity-is required under MAP-21 to invest a portion of its CMAQ funding in projects that 

reduce PM2.5 directly or its precursors. Provisions giving priority to PM2.5 emission reductions 

and directing a small portion of a state’s CMAQ funding to PM2.5 nonattainment and 

maintenance areas are specified in the MAP-21 (MAP-21) and the Interim Program Guidance 

issued by DOT on November 12, 2013. The law does not require additional CMAQ funding for 

PM2.5 areas, but directs a portion of the state’s CMAQ funds to those areas. Existing program 

policy and flexibility gives states discretion to allocate the remaining CMAQ funds within the 

state to other eligible areas according to their priorities. The CMAQ program is administered by 

the U.S. DOT and is not subject to this rulemaking.

P. Efforts to Encourage a Multi-Pollutant Approach When Developing 2008 Ozone SIPs

1. General support for a multi-pollutant approach
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Commenters (0156, 0164, 0166 and 0169) supported having the option of a multi-pollutant 

approach to SIP planning requirements. Commenters (0156 and 0166) noted that, substantial 

efficiencies in SIP and transportation planning development could be realized by aligning 

NAAQS schedules, but it is unknown how that can occur considering existing statutory 

requirements.

Commenter (0166) stated that, perhaps the best that can be done is to allow credit for emission 

reductions planned under one program when implementing another program, an approach that 

the EPA already allows to a certain extent. Commenter (0166) encouraged the EPA to allow 

states to take credit for programs that may not yet have been fully implemented, but stated that, if 

the EPA moves forward with this proposed approach on integrated planning, it must provide 

sound legal justification for doing so. 

Commenter (0169) stated that, a paradigm shift is necessary to move away from a pollutant-bypollutant approach in favor of multipollutant air quality management and to account for the 

current rigidity in SIP deadlines that only serves to foster a sue and settle approach to 

policymaking. Until such time that the CAA can be revised, Commenter (0169) advised that, 

consistent interpretation of the CAA is vital to avoid the consequence of further promoting 

regulation by litigation. 

Response: The EPA supports multipollutant planning where possible. Regarding the comment 

encouraging the EPA to allow states to take credit for programs that may not yet have been fully 

implemented, please See section III.B in the final preamble for details regarding the EPA’s 

policy on this subject. 

2. Do not support a multi-pollutant approach

Comment: Commenter (0159) stated, they preferred a single pollutant approach.

Response: Multipollutant planning is not required under this rule.

Q. How does this proposed rule apply to tribes?

Comment: The rule affects tribes

Commenter (0181) disagreed with the proposed rule’s claim that, "it would not have a substantial 

direct effect on one or more Indian tribes, since no tribe has to develop a SIP under these 

proposed regulatory revisions" (page 34226). The Commenter stated that, Indian tribes whose 

interests and air quality levels were improperly overlooked when nonattainment designations and 

classifications were made, whose air quality is not accurately reflected by these older 

designations and classifications and whose nonattainment is due overwhelmingly (if not entirely) 

to transport, will be adversely affected by the rule. The Pechanga Band falls into this category. 

When the EPA established the new ozone NAAQS to replace the oxidants NAAQS in 1979, it 

designated the entire portion of Riverside County in the South Coast Air Basin, which had been 

designated as nonattainment for the oxidants NAAQS and which includes the Pechanga Indian 

Reservation, as nonattainment for the ozone NAAQS. This action was taken without consulting 
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Pechanga. 

The Commenter argued that, under the 1990 CAA Amendments, the designation of 

"nonattainment" and the boundary of the Metropolitan Los Angeles Air Quality Control Region 

1-hour ozone nonattainment area were carried forward by operation of law and the Los AngelesSouth Coast Air Basin nonattainment area was classified as "Extreme" ozone nonattainment –

again without consultation with Pechanga, in derogation of the 1984 policy announced by 

Administrator William D. Ruckelshaus requiring the agency to "assure that tribal concerns and 

interests are considered whenever the EPA's actions and/or decisions may affect reservation 

environments." (See 78 FR 34178, 34209)

The Commenter stated that, the Pechanga Indian Reservation straddles the boundary between 

southwestern Riverside County and San Diego County, and it is undisputed that its ozone levels 

and its air quality in general are far better than those of the Los Angeles - South Coast Air Basin 

as a whole, a fact recognized by the EPA when it announced the designation of "Moderate" 

nonattainment of the 2008 ground-level ozone standard for the Pechanga Band of Luiseno 

Indians Nonattainment Area in 2012. The Pechanga Indian Reservation, approximately 6,700 

acres, is now divided into two different 8-hour ozone designations, with the portion of the 

Reservation located in San Diego County being in attainment of all ozone standards, and the 

contiguous portion located in Riverside County being in "Moderate" non-attainment of the 2008 

standard and "Extreme" nonattainment of the 1-hour standard. Of course, this division has no 

basis in science or common sense. The Reservation has no industry, no major roadways and only 

one significant commercial entity located within its boundaries and historically tolerated high 

ozone transport from the heavily polluted Los Angeles - South Coast Air Basin. 

Commenter (0181) stated that, the facts of Pechanga's predicament are:

1. Pechanga's current nonattainment designation for the 1-hour ozone standard and the 1997 8-

hour standard are based entirely on data from within the South Coast Air Basin and not on data 

from within the Pechanga Reservation or the immediately adjacent (attainment) areas in San 

Diego County.

2. The South Coast Air Basin is subject to stringent federal requirements that can only result in 

improvements in air quality within the Pechanga reservation.

3. Due to the overwhelming contribution of emissions from the South Coast Air Basin to 

Pechanga's ozone levels, the only way that Pechanga could make the demonstrations required by 

the proposed rulemaking to eliminate the anti-backsliding requirements would be for Pechanga 

to rely on planning, regulations and commitments by other jurisdictions - the South Coast 

AQMD and the State of California-that are completely outside of Pechanga's control and which 

may have economic interests in conflict with or adverse to those of the Pechanga Band.

Commenter (0181) believed that, to require a geographically small entity with no industry to 

demonstrate that its attainment of a revoked standard is due to permanent and enforceable 

emission reductions when, in fact, there is virtually nothing within its jurisdiction to reduce, and 
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to require a demonstration that controls will remain in place when the controls affecting ozone in 

its territory are under a different jurisdiction, places an undue burden on a tribe whose 1-hour 

classification and designation were improperly, unfairly and illogically set in the first place.

Response: The tribe expresses concerns about its inclusion in the South Coast Air Quality 

Control Region, which is a nonattainment area. This comment is beyond the scope of this rule, 

which sets forth the requirements for SIPs for ozone nonattainment areas. It does not address 

how air quality control regions are established or designated. 

The CAA section 107(d) establishes the requirement for the EPA to designate areas following 

promulgation of a new or revised NAAQS. Section 107(d) does not explicitly reference Indian 

tribes or Indian country. However, tribes are able to participate in the designations process, and 

the EPA encourages them to do so. 

The EPA included the Pechanga Reservation in the initial one-hour ozone designation for the 

South Coast nonattainment area in 1978.27 The Pechanga Reservation, in a September 13, 2012 

letter from Mark Macarro, Chairman of the Pechanga Reservation, requested correction of the 

EPA’s inclusion of the Pechanga Reservation in the initial one-hour ozone designation for the 

South Coast nonattainment area in 1978. The chairman asserted that including the tribe in the 

designation area was incorrect based on air quality considerations at the time and the failure to 

consult with the Tribe or to consider the Tribe’s interests. The EPA recognizes that there have 

been long-standing issues arising from the inclusion of the reservation in the South Coast ozone 

nonattainment area. 

The EPA has reviewed the request from the tribe and communicated to the tribe that the EPA 

was not inclined to pursue the error correction approach at this time. Under section 110(k)(6), the 

EPA must first determine that the agency’s initial action promulgating the designation of the 

South Coast to include the Pechanga Reservation was in error, and EPA is not convinced that 

such action was in error. The EPA would encourage the tribe to continue to work with the EPA 

Region IX Air Division to resolve the tribes’ concerns.

The EPA regrets any problems regarding past coordination with the tribe. We note that the 

agency did not have a consultation policy at the time that various actions noted by the 

Commenter took place. However, in order to improve the EPA’s efforts to ensure adequate 

communication and coordination with tribes, the EPA, on May 4, 2011, released the “EPA 

 

27 See 43 FR 8962 (March 3, 1978)
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Policy on Consultation and Coordination with Indian Tribes.”28 The policy is a result of the 

Presidential Memorandum on Tribal Consultation issued November 5, 2009, directing agencies 

to develop a plan to implement fully Executive Order 13175.29

R. What are the requirements for the Ozone Transport Region (OTR)?

1. VOC controls

Comment: Commenter (0130) stated that imposition of VOC controls in areas that are NOxlimited is burdensome to both the regulated entity as well as the state, which must determine, 

implement and enforce these controls. The commenter added that allowing NOx substitution for 

VOC should extend beyond section 182(b)(2) RACT requirements to those required for areas 

within the OTR. The commenter stated that studies have shown that many areas in the OTR, 

including Northern Virginia, show little or no benefit to ground-level concentrations when 

significant reductions in anthropogenic VOC emissions are modelled. The commenter asked the 

question, why impose additional regulations and requirements when science indicates that ozone 

concentrations will not improve as a result? The commenter urged the EPA to implement this 

common sense approach.

Response: The EPA agrees that there are examples of modeling suggesting that ozone formation 

in some areas is NOx-limited, such that changes in anthropogenic VOC emissions will have little 

effect on ozone concentrations. The EPA agrees that today’s understanding of the role of NOx

reductions would suggest that, in some areas, it would be relatively more efficient to focus 

attainment planning efforts on achieving reductions in NOx rather than VOC emissions. 

However, the CAA section 182(b)(1) expressly requires the 15 percent ROP plans to reduce 

emissions of VOC. It does not provide discretion to meet these requirements by reducing 

emissions of other pollutants. Where Congress intended to allow such a substitution, it 

specifically provided so, such as in section 182(c)(2)(C) which allows NOx to be substituted for 

VOC in the 3 percent annual RFP plans for Serious and above areas.

The EPA has already developed information that may be assist the commenter. The EPA 

developed the NOx Substitution Guidance, December 1993, which provides a procedure that can 

be applied to meet the section 182(c)(2)(B) RFP requirement as well as the section 182(c)(2)(C) 

equivalency demonstration requirements. This guidance is intended to facilitate implementation 

of the most effective ozone precursor control strategies, while meeting the intent of the CAA 

RFP provisions. This document can be accessed at the following web address: 

 

28 The “EPA Policy on Consultation and Coordination with Indian Tribes,” can be accessed at 

the following web site: http://www.epa.gov/indian/pdf/cons-and-coord-with-indian-tribespolicy.pdf

29 Executive Order 13175 can be accessed at the following website: 

http://www.gpo.gov/fdsys/pkg/WCPD-2000-11-13/pdf/WCPD-2000-11-13-Pg2806-2.pdf
189

http://www.epa.gov/ttn/caaa/t1/memoranda/noxsubst.pdf. The EPA, on August 5, 1994, issued a 

memorandum titled, Clarification of Policy for NOx Substitution, John S. Seitz, Director, Office 

of Air Quality Planning and Standards, which issues a clarification on NOx substitution for ROP 

plans, specifically, what the EPA will accept as evidence that NOx substitution for VOC 

reductions is a viable approach. This memorandum can be accessed at the following web 

address: http://www.epa.gov/ttn/caaa/t1/memoranda/clarisub.pdf.

2. Emission reduction credits

Comment: Commenter (0144) urged EPA to allow for emission reduction credits from certain 

control strategies made within the Ozone Transport Region (OTR) states that occurred between 

2008 and the year of the baseline emissions inventory (2011), if 2011 is used as the baseline 

inventory, so that states that made early reductions in ozone precursors are not economically and 

environmentally disadvantaged.

Response: In the final rule, the EPA allows states to take emission reduction credits for certain 

control strategies implemented with the OTR if the baseline year the state selects is consistent 

with the timing of those reductions. However, if the state selects 2011 as its baseline year, 

emissions reductions occurring in the years 2008-2010 are not creditable against a 2011 baseline.

3. NOx substitution

Comment: Commenter (0166) opposed the EPA’s proposal to allow nonattainment areas in the 

OTR that are subject to section 182(b)(1) of the Act for the first time to substitute NOx

reductions for otherwise-required VOC reductions. [Also See section 2.C.2, 2008 ozone 

nonattainment areas where portions have a previously approved 15 percent VOC reduction plan]

Response: Several Commenters raised objections to the EPA’s proposal that would allow only 

areas in the OTR to meet the RFP requirements by allowing NOx substitutions. The Commenters 

argued that, it would be better to allow all areas to take advantage of this alternative. Attainment 

areas in the OTR were not required to adopt 15 percent RFP plans under section 184 of the CAA. 

We discussed certain VOC reduction measures in the proposal. We expected that the VOC 

reductions from those measures would account for a significant portion of the 15 percent 

requirement for areas designated nonattainment. We reasoned that since attainment areas in the 

OTR were required to adopt and implement many of the same measures applied in nonattainment 

areas, we proposed that such areas should be treated as having met the 15 percent VOC reduction 

requirement if they can demonstrate that they did, in fact, achieve a 15 percent reduction in VOC 

emissions, even though they of course would not have submitted a 15 percent plan as they were 

not subject to the 15 percent requirement at that time. The EPA has reconsidered its proposal and 

now believes it does not have authority under the CAA to allow NOx substitution for VOC 

emissions reductions for the 15 percent ROP in any area, including an area located in the OTR, 

unless the area has previously submitted, adopted and implemented a SIP providing for a 15 

percent VOC reduction in emissions from the area’s baseline emissions in the 6 years following 

the baseline emissions inventory year consistent with the requirement in section 182(b)(1) and 

the prior approach for the 1997 ozone NAAQS. 40 CFR 51.910(a)(1)(i). The EPA is not 
190

finalizing either of the proposed approaches that would have allowed areas to meet the 15 

percent ROP requirement in whole or in part with NOx reductions in lieu of VOC reductions. 

4. Areas with a previously submitted 15 percent VOC reduction plan

Comment: Commenter (0163) stated that, areas within the OTR, including new nonattainment 

areas, that have already implemented VOC control measures, such as RACT, motor vehicle 

inspection and maintenance programs, and Stage II or comparable measures, in response to 

statutory requirements, can be assumed to have met and would not have to document meeting the 

15 percent RFP requirement. [Also See section 2.C.2, 2008 ozone nonattainment areas where 

portions have a previously approved 15 percent VOC reduction plan]

Response: The EPA has reconsidered its proposal and now believes it does not have authority 

under the CAA to allow NOx substitution for VOC emissions reductions for the 15 percent ROP 

in an area, including an area located in the OTR, which has never adopted and implemented a 

SIP providing for such VOC emission reductions. Thus, we agree with the comments that the 

CAA does not allow such substitution and disagree with comments suggesting that EPA allow 

substitution. We are finalizing that where a 2008 nonattainment area has previously met the 

CAA requirement for a 15 percent ROP VOC reduction plan for the entire area, the area is not 

required to fulfill that requirement again.

5. lnterpollutant Offset Substitution in the OTR

Comment: Commenter (0130) suggested that, the proposal clarify that this exchange may be 

implemented in the OTR regions as well as nonattainment areas outside the OTR. The 

commenter believed that permits for facilities to construct or modify in nonattainment areas need 

to ensure that the expansion or new facility will not hinder progress toward compliance with the

NAAQS. The commenter further believed that requiring facilities to obtain offsets for pollutants 

that only minimally reduce ozone concentrations is overly burdensome and should be 

streamlined. The commenter believed that in areas where NOx is the predominant ozone 

precursor, which the commenter alleged is the case in most areas on the eastern seaboard, NSR 

offset requirements for areas within and outside the OTR should reflect this fact. In these areas, 

NSR rules should not mandate that VOC offsets be acquired for major permit actions. The 

commenter urged the EPA to allow substitution of NOx emissions reductions to satisfy VOC 

offset requirements into the final rule.

Response: The EPA has addressed interprecursor offset substitution in the discussion section 

I.3.b, and regulation amendment for 40 CFR 51.165(a)(11) and part 51 Appendix S IV.G.5. The 

changes in the regulatory as noted in the discussion did not specifically address use within the 

OTR regions, however the EPA does not anticipate precluding the use of interpollutant offset 

substitution as long as such trades are consistent with existing policy and legal requirements for 

such trades.6. Stage II vapor recovery

Comment:
191

Commenter (0143) stated that, the DEP understands that the proposed rule "would have no effect 

on the continuing independent CAA section 184(b)(2) requirement for OTR states to implement 

Stage II programs or measures capable of achieving emissions reductions comparable to those 

achieved by Stage II", nonetheless, DEP strongly supports the proposed revisions to the antibacksliding rules. (0143)

Response: The EPA believes its revision to the existing anti-backsliding rules, which does not 

include the Stage II vapor recovery program previously required by CAA section 182(b)(3) in 

the list of measures that need to be retained for anti-backsliding, is consistent with the EPA’s 

May 16 2012, Stage II action, 77 FR 28772. In that action, the EPA determined that ORVR 

systems are in widespread use nationally, and the EPA waived the CAA section 182(b)(3) 

requirement for states to adopt and submit programs for implementation of the Stage II vapor 

recovery system at gasoline dispensing facilities located in Serious and above ozone 

nonattainment areas, pursuant to authority provided in CAA section 202(b)(6). However, the 

Commenter is correct that, OTR states must continue with the independent CAA section 

184(b)(2) requirement to implement Stage II programs or measures capable of achieving 

emissions reductions comparable to those achieved by Stage II, consistent with the “Guidance on 

Removing Stage II Gasoline Vapor Control Programs from SIPs and Assessing Comparable 

Measures” August 7, 2012, (EPA–457/B–12–001).

S. Are there any additional requirements related to enforcement and compliance?

The EPA did not propose any specific regulatory provisions related to compliance and 

enforcement. The EPA did not solicit comment on this section and none were received.

T. What are the requirements for addressing emergency episodes?

Comment: Commenter (0160) supported the proposed use of the Administrator's discretion to 

exempt ozone nonattainment areas from the emergency episode planning requirements originally 

required for the revoked 1-hour standard. Commenter (0160) stated that, modern information 

technology has replaced these "paper plans" with real-time data and improved public notification 

systems. 
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Response: The EPA did not propose to exempt emergency episode planning requirements but 

proposed to apply the existing requirements for emergency episodes (40 CFR part 51, subpart H)

to the 2008 ozone NAAQS, whereby SIPs would identify areas by priority classification and 

contain contingency plans to prevent pollutant concentrations from reaching levels that would 

cause significant harm to the health of persons. We did not receive any adverse comments on this 

proposal, and we are finalizing this proposal without changes. The proposed rule also specified 

that the existing significant harm level for ozone of 0.6 ppm, 2-hour average (40 CFR 51.151)

would continue to apply for purposes of developing emergency episode plans. We did not 

receive any adverse comments on this proposal, and we are finalizing this proposal without 

changes.

U. How does the ‘‘Clean Data Policy’’ apply to the 2008 ozone NAAQS?

1. Support clean data policy

Comment: Commenters (0159, 0163, 0172, 0173 and 0179) supported the EPA’s proposed 

approach to the clean data policy.

Commenter (0159) stated that, requirements designed to bring an area into attainment should be 

suspended once the goal of attainment has been achieved, provided the area continues its 

monitoring program and continues to attain the relevant standard. Commenter (0173) stated that, 

not only has the Clean Data Policy been upheld in court but it is also essential to streamlining 

unnecessary administrative burdens for areas that are currently attaining the NAAQS. 

Commenter (0179) supported the policy since it reduces burdens on areas that attain the 

NAAQS. Commenter (0179) requested that, the EPA expeditiously redesignate and/or reclassify 

areas using its CAA section 107(d)(3) authority for which states have submitted "clean data" 

certification and redesignation/maintenance SIPs.

Response: The EPA appreciates the Commenters’ support of the Clean Data Policy. As stated in 

the Clean Data Policy, the attainment demonstration, RFP requirements and contingency 

measure requirement are designed to bring an area into attainment. Once this goal has been 

achieved, we believe the statute no longer requires submission of plans designed to bring the area 

into attainment and thus it is appropriate to suspend the obligation that states submit plans to 

meet these goals, so long as the area continues to attain the relevant standard. The EPA Regional 

Offices will act on redesignating areas based on any section 175A submittals that are received in 

as expeditious a manner as possible. 

V. What assistance programs is the EPA considering for implementation of the 2008 ozone 

NAAQS?

1. Ozone Advance 

Comment: Commenter (0140) stated that, because areas participating in the EPA’s Ozone 

Advance Program are undertaking significant efforts to limit emissions within their areas and 

stay in compliance with federal ozone standards, the EPA should ensure in this rulemaking that it 
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will exercise the maximum discretion available to it under the CAA in implementing the 2008 

ozone NAAQS to these areas in recognition of these efforts.

Commenter (0163) stated, the EPA should assure that areas implementing ozone advance are 

currently still in attainment with the NAAQS and, if these areas are no longer meeting the 

NAAQS with the most recent data, the EPA should redesignate these areas to nonattainment and 

require they come into attainment as specified in subpart 2.

Commenter (0169) expressed support for the Ozone and PM Advance Programs and stated that 

their shared goal and focus should be attainment of the ozone NAAQS as soon as practical to 

provide public health protection as expeditiously as possible. Therefore, this process should 

reward and provide maximum flexibility to programs that can attain the standard on an 

accelerated basis. As the EPA is aware, 13 out of 14 areas across the nation were successful in 

implementing an 8-hour Ozone Early Action Compact (EAC) for the 1997 ozone NAAQS. 

These areas were provided the incentive of a deferred effective date of a nonattainment 

designation as long as requirements of the EAC were followed, including the implementation of 

measures earlier than required. The EACs served to help motivate local partners to implement 

strategies to help avoid a nonattainment designation altogether. This saved countless state, local, 

and business man-hours and dollars and protected public health by maintaining ozone levels 

below the NAAQS in participating areas. While the EPA has discontinued the EAC program and 

its resulting deferment of nonattainment designations, realizing the benefit of it in principal has 

led to the Ozone and PM Advance Program which serves to again encourage attainment. SC has 

signed on and been accepting into both the Ozone and PM Advance Programs and looks forward 

to continuing our work with stakeholders via our state-wide Coalitions. 

Response: A Commenter noted that, the EPA has discretion to determine whether areas 

designated attainment for the 2008 ozone NAAQS but that have since violated the standard 

should be redesignated nonattainment. The Commenter recommends that, if an attainment area 

participating in the EPA’s Advance Program is not meeting the 2008 standard, the EPA should 

not designate the area nonattainment as a result of the area’s participation in Ozone Advance.

This issue is addressed in the Ozone Advance program guidance, which states that if violations 

of the ozone NAAQS occur despite an area’s participation in Ozone Advance, the EPA would 

consider the factors in the CAA section 107(d)(3)(A), which include “air quality data, planning 

and control considerations, or any other air quality-related considerations the Administrator 

deems appropriate.” The guidance additionally indicates that where control measures and 

programs are actively being implemented by an area, the EPA may allow time to determine 

whether such measures and programs bring the area back into attainment. This is not meant to 

suggest that participation in Ozone Advance can shield an area from being redesignated 

nonattainment if the area eventually violates the ozone NAAQS. However, it is appropriate for 

the EPA to consider an area’s active pursuit of control measures and programs (whether via 

Ozone Advance or otherwise) as one factor among the set of factors it considers when 

determining whether to exercise its discretion to revise the area’s designation to nonattainment.

Another Commenter suggested that, the EPA should redesignate Ozone Advance areas to 
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nonattainment if they are no longer meeting the 2008 ozone NAAQS based on the most recent 

data. The EPA agrees that participation in Ozone Advance is not a guarantee against a future 

redesignation to nonattainment. If violations of the ozone NAAQS occur despite an area’s 

participation in Ozone Advance, the EPA would consider the factors in CAA section 

107(d)(3)(A), which include “air quality data, planning and control considerations, or any other 

air quality-related considerations the Administrator deems appropriate.” To the extent an area is 

actively implementing control measures and programs, the EPA may allow time to determine 

whether such measures and programs bring the area back into attainment.

Lastly, a Commenter emphasized the benefits of flexible, expeditious approaches that can help 

areas achieve attainment of the ozone NAAQS. In particular, the Commenter noted the success 

of the Early Action Compact program for the 1997 ozone NAAQS and the current Ozone and 

PM Advance programs as examples of helpful, flexible approaches that encourage areas attain 

the NAAQS expeditiously. The EPA shares the commenter’s view that expeditious attainment of 

the NAAQS is needed to ensure public health is protected, and that flexible attainment 

approaches can play an important role in helping areas to achieve air quality improvements.
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W. What is the deadline for states to submit SIP revisions to address the CAA section 185 

penalty fee provision for Severe and Extreme areas?

1. Support the proposed schedule 

Comment: Commenter (0163) agreed with the proposed schedule for submitting CAA section 

185 SIPs. 

Response: The EPA thanks the Commenter for their support of the proposed schedule for 

developing and submitting section 185 SIPs to the EPA. Consistent with CAA section 182(d)(3), 

the final rule requires states with areas initially classified as Severe or Extreme for the 2008 

ozone NAAQS to submit a section 185 SIP no later than 10 years after the effective date of 

designation and classification for the 2008 ozone NAAQS. For areas that are reclassified to 

Severe or Extreme at any other time, the EPA will establish an appropriate fee program SIP 

submission deadline as part of the reclassification action.

X. Other Comments

1. Federal control measures

Comment: Commenters (0139, 0141, 0149, 0155 and 0157) encouraged the EPA to continue to 

regulate mobile and stationary sources through national measures.

Commenter (0168) asserted that, emission reductions achieved by national rules will not only 

reduce emissions from within what the Commenter characterized as the arbitrarily small 

nonattainment areas that are covered by this proposal, but will also reduce emissions from the 

broader area that is the primary cause of nonattainment. 

Commenter (0143) encouraged the EPA, when finalizing the rule, to use the EPA's existing 

authority to gather emissions data and update current program standards that have the potential to 

lower emissions.

Commenters (0139 and 0150) stated, the EPA needs to share the responsibility to attain the 

standards and to have the authority to impose requirements that will enable the standards to be 

attained. The Commenter believed that, the existing provisions of the CAA gives state and local 

governments the responsibility to attain the NAAQS, yet it deprives them of the ability to 

regulate the sources that, in California at least, contribute by far the greatest amount of 

emissions—mobile sources. In contrast, the EPA is given the ability to regulate mobile sources, 

but is not given the responsibility to actually attain the standards. We recognize that the CAA 

attempts to address this concern to some extent by allowing California to set emission standards 

for new mobile sources with a waiver or authorization from EPA, under section 209. But despite 

California having used these provisions to the greatest extent feasible, there is still a large gap 

between existing regulation and attainment needs. The EPA needs to have the authority to (1) 

regulate existing as well as new on-road and NONROAD sources; (2) require airlines, shippers, 

and railroads to route their cleanest equipment to the areas that need emission reductions the 
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most; and (3) regulate marine vessels flying foreign flags but doing substantial business within 

U.S. ports. 

Commenter (0150) expressed their biggest concern with the existing provisions of the CAA is 

that it gives state and local governments the responsibility to attain the NAAQS, yet it deprives 

them of the ability to regulate the sources that, in California at least, contribute by far the greatest 

amount of emissions-mobile sources. The commenter explained that EPA is given the ability to 

regulate mobile sources, but is not given the responsibility to actually attain the standards. The 

commenter recognized that the CAA attempts to address this concern to some extent by allowing 

California to set emission standards for new mobile sources with a waiver or authorization from 

the EPA, under section 209. The commenter specified that in their state, despite having used 

these provisions to the greatest extent feasible, there is still a large gap between existing 

regulation and attainment needs. The commenter proposed the EPA needs to regulate "federal 

sources" by an amount proportionate to their contribution to the problem. To attain even the 

1997 ozone standard, the South Coast needs an additional 65 percent NOx reductions beyond 

what would occur in the attainment year of 2024 without further regulation. Since mobile 

sources contribute over 80 percent of ozone precursors, they must contribute the lions' share of 

the reductions. The Commenter believed that, the EPA needs to take responsibility for attaining 

the national standards-and it needs to have the tools to be able to do so. The commenter 

recommended that EPA needs to have the authority to (1) regulate existing as well as new 

ONROAD and nonroad sources; (2) require airlines, shippers and railroads to route their cleanest 

equipment to the areas that need emission reductions the most and (3) regulate marine vessels 

flying foreign flags but doing substantial business within U.S. ports. The commenter offered that 

these issues are further discussed in the testimony of Dr. Barry Wallerstein, Executive Officer of 

the SCAQMD, on August 2, 2012, before the House Subcommittee on Energy and Power. This 

testimony was included as an attachment to the SCAQMD letter of August 21, 2012, regarding 

RFP, which is attached to comment 0150. The commenter summarizes that, the EPA needs to 

share the responsibility to attain the standards and to have the authority to impose requirements 

that will enable the standards to be attained. 

Commenter (0168) suggested that, the list of national rules that the EPA adopts be expanded to 

include other requirements that have been implemented in the OTR states, which include updated 

Architectural and Industrial Maintenance Coating (AIM), auto body coating, and others. 

Commenter added that, the EPA discussed in the proposal HEDD, vehicle I/M for OBD 

equipped vehicles and the removal of Stage II vapor recovery systems, which also may be 

candidates for national rules.

Response: The EPA appreciates the Commenter’s affirmation that the EPA’s determination of 

widespread use of ORVR adequately supports the EPA’s waiver of requirements for Stage II 

vapor recovery systems. The EPA’s decision to waive the Stage II gasoline vapor recovery 

requirement for ozone nonattainment areas was based on an analysis that was available for public 

review and comment in the EPA’s rulemaking process. Overall, the analysis demonstrates that 

ozone-precursor emission control benefits of basic Stage II programs decline as older vehicles 

are replaced by newer ORVR-equipped vehicles, and that basic Stage II systems become 

increasingly less cost-effective ozone control measures. The EPA's analysis incorporated all 
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types of refueling events at gasoline dispensing facilities (GDFs) including: (a) ORVR vehicles 

at Stage II GDFs; (b) ORVR vehicles at non Stage II GDFs; (c) non-ORVR vehicles at Stage II 

GDFs; and (d) non-ORVR vehicles at non Stage II GDFs. The EPA calculated the emissions in 

these four segments but did not address storage tank emissions since our analysis concluded that 

these emissions would be about the same with ORVR alone or with Stage II alone. Early in the 

rulemaking process, we published an analysis which concluded that storage tank vent emissions 

would be the same or less under any refueling scenario because the GDF National Emission 

Standards for Hazardous Air Pollutants rule for GDFs require pressure/vent (p/v) valves. In these 

analyses, the EPA did not indicate that storage tank vent emissions would be zero, but that they 

would not increase if Stage II was removed. Furthermore, the EPA concluded that storage tank 

vent emissions related to ORVR/vacuum assist nozzle incompatibility would gradually increase 

if Stage II was retained but would be eliminated if Stage II was removed. Based on public 

comment on the July 15, 2011, Notice of Proposed Rulemaking (NPRM), we prepared and 

published an analysis which quantified this effect and we included these emissions in the 

assessment that supported the EPA’s determination of when Stage II could be removed. Our 

analysis and all of the data considered in our determination was available for public review and 

comment during the EPA’s rulemaking process. All comments received on the NPRM were 

considered and addressed in our Response to Comments document supporting the May 16, 2012 

final rule (77 FR 28772).

Comment: Commenter (0147) agreed with the statement in the proposed rule, which highlights 

achievements already made by the solvents industry and downstream users in reducing VOC 

emissions. 

Response: The EPA appreciates the Commenter’s support.

2. Subpart 1 and Subpart 2

Comment: Commenter (0140) stated that, the EPA should only apply Subpart 2 requirements to 

ozone nonattainment areas in cases where the courts have explicitly ruled that the EPA must 

apply these requirements. The Commenter stated that, under the Chevron U.S.A. v. NRDC twostep test for determining whether to grant deference to a government agency’s interpretation of a 

statute, the courts grant a government agency discretion in interpreting a statute if Congress has 

not “spoken directly to the precise question at issue,” and if “the agency’s answer is based on a 

permissible construction of the statute.” In this case, the specific question at hand is whether the 

“Subpart 2” requirements under section 182 of Title I of the 1990 CAA Amendments must be 

used to implement the 2008 ozone NAAQS for areas with 8-hour ozone at or below 0.09 ppm. 

The Supreme Court’s ruling in Whitman v. American Trucking Assns., Inc. (2001), and the 

Appeals Court for the D.C. Circuit’s ruling in South Coast Air Quality Management District v. 

EPA (2006 and 2007) both indicated that Congress did not “clearly intend Subpart 2 to be the 

exclusive, permanent means of enforcing a revised ozone standard in nonattainment areas,” and 

that the EPA’s implementation of the 1997 ozone standard violated the CAA “insofar as it 

subjects areas with 8-hour ozone in excess of 0.09 ppm to Subpart 1.”
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The cumulative impact of these rulings is to allow the EPA to implement an 8-hour ozone 

standard under Subpart 1 for areas with 8-hour ozone levels at or below 0.09 ppm, as long as 

such a rulemaking is based on a permissible construction of the statute. The 2007 South Coast 

decision only precludes the EPA from a construction of the statute that, “rel[ies] upon its 

preference for regulatory flexibility in setting the boundary between Subpart 1 and Subpart 2.” 

The CACAC recommends that the EPA instead rely on the statute’s explicitly stated purpose of 

Title I “to encourage and assist the development of regional air pollution prevention and control 

programs” under section 101(b)(4) and the explicitly stated goal of the statute “to encourage or 

otherwise promote reasonable Federal, state and local government actions, consistent with 

provisions of this Act, for pollution prevention” under section 101(c) as the basis for using 

Subpart 1 to implement the 2008 standard for areas with 8-hour ozone below 0.09 ppm. Insofar 

as application of Subpart 2 requirements to 8-hour ozone nonattainment areas with 8-hour ozone 

levels at or below 0.09 ppm act as a disincentive to states, local governments and businesses in 

“attainment” areas taking proactive measures to avoid nonattainment, it would be contrary to the 

stated Congressional intent for the statute.

Specifically, the requirements for emission reductions beyond what may be required for 

expeditious attainment under Subpart 2’s RFP requirement create a set of regulatory 

requirements that would inadvertently punish an area for taking proactive emission reduction 

measures prior to a “baseline” year used to establish emission reduction targets. For the AustinRound Rock MSA, for example, under the Early Action Compact (EAC) and then again under 

the 8-Hour Ozone Flex Program (8-O3 Flex), the local governments and the TCEQ adopted a 

host of regulations and emission reduction measures that reduced the area’s NOx and VOC 

emissions, including a vehicle inspection and maintenance program, stage 1 vapor recovery 

requirements, degreasing restrictions, cutback asphalt restrictions, heavy-duty vehicle idling 

restrictions, power plant emission reductions, Texas Low-Emission Diesel (TxLED), and a diesel 

retrofit/repower/replacement program (the Emission Reduction Incentive Grants, or “ERIG,” 

under the Texas Emission Reduction Plan, or “TERP” program). These emission reductions 

began in 2004 and have significantly reduced the emissions up to today, including in any 

baseline year that would be used for calculating RFP targets if the Austin-Round Rock MSA 

were to be designated nonattainment for the 2008 ozone NAAQS at some point in the future. The 

local governments and TCEQ were willing to pursue these and other emission reduction 

measures in order to maintain compliance with an ever-stricter ozone standard with the explicit 

agreement from the EPA that the emission reduction measures would be “creditable” to any 

future ozone SIP requirements (including RFP).

The Commenter stated that, it is easy to see how implementation of the 2008 ozone NAAQS 

using Subpart 2’s requirements for an area like the Austin-Round Rock MSA could wind up 

“punishing” it for taking proactive measures by requiring a 15 percent VOC reduction (or 3 

percent per year NOx reductions) from an already-reduced emissions baseline. For example, if 

the Austin-Round Rock MSA’s typical ozone season weekday VOC emissions in 2011 were 95 

tons per day (tpd), but would have been 100 tpd if it not adopted proactive emission reduction 

measures, it’s target VOC emissions level would be lower (80.75 tpd, or 85 percent of 95 tpd) 

than what would have been required if it had not taken those proactive measures (85 tpd, or 85 

percent of 100 tpd). The extra 4.25 tpd of VOC emission reductions that an area might have to 
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make under this scenario would provide a powerful disincentive to it or any other area taking 

similar proactive measures. Similarly, if a major point source has reduced its emissions and 

voluntarily modified its permit to reflect the lower emissions prior to a “baseline” year, it would 

also be “punished” for taking this beneficial, proactive measure since these emission reductions 

would not be available for use as an offset if the area was designated nonattainment. Since doing 

so would provide disincentives for taking proactive measures to attain and maintain the 2008 

ozone NAAQS, implementing it using Subpart 2 for areas that the EPA is not required to use 

them would be contrary to the purpose of the statute and would not serve any useful purpose in 

attaining and maintaining the standard.

The Commenter suggested that, the EPA could also use the definition of “RFP” under section 

171(1) as the basis for waiving the section 182 RFP requirements for areas with 8-hour ozone 

design values of 0.09 ppm or less. Section 182(b)(a)(i) specifies that the SIP must require a 15 

percent VOC reduction from a 1990 baseline and “such specific annual reductions in emissions 

of VOC and NOx as necessary to attain the 2008 ozone NAAQS by the attainment date 

applicable under this Act.” Section 171(1) states that, “The term ‘RFP’ means such annual 

incremental reduction in emissions of the relevant air pollutant as are required by this part or 

may be reasonably be required by the Administrator for the purpose of ensuring attainment of the 

applicable NAAQS by the applicable date” (emphasis added). The specific requirements of 

section 182(b)(a)(i) beyond what was defined in section 171(1) were aimed at attainment the 1-

hour ozone standard in effect at the time of its passage, and therefore may need to still be applied 

to areas with 8-hour ozone above 0.09 ppm (the 8-hour equivalent of the 1-hour standard). 

However, no examination of the scientific evidence for many areas, including for the AustinRound Rock MSA, would interpret the general RFP requirements under section 171(1) and 

section 172(c)(2) as requiring a 15 percent VOC reduction irrespective of whether such a 

reduction would be effective at reducing ozone levels. For the Austin area, even a 100 percent 

reduction in anthropogenic VOC emissions would not likely reduce local ozone levels by any 

more than 0.7 parts per billion, based on modelling performed by the University of Texas at 

Austin.

The Commenter believed that, since implementation of the 2008 ozone NAAQS under Subpart 1 

would still require RFP, the CACAC recommends that for areas with 8-hour ozone design values 

at or below 0.09 ppm (either 94 or 90 ppb, depending on interpretation), the RFP requirement be 

tied only to the amount of emission reductions required for attainment between a baseline year 

and an attainment year as specified in an attainment demonstration. The requirement for RFP 

would be simply to demonstrate that emission reductions envisioned in the attainment 

demonstration were being implemented at the earliest date that could reasonably be expected, 

given economic and technical feasibility. This could entail a simple schedule of emission 

reductions that would occur in the intervening years between the baseline and attainment year. 

For a “Moderate” area with an 8-hour ozone design value of 0.09 or less, this could entail a 

demonstration that half of the emission reductions would have occurred within 3 years of 

designation, and that all of the remaining emission reductions would occur between the date of 

submission of the SIP and the beginning of the ozone season for the attainment year. Such a 

demonstration would avoid requiring states to adopt additional VOC emission reduction 

measures strictly for RFP purposes, and beyond what was required to attain the standard. The 
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same is true of the section 182 requirements for adoption of RACT for VOC sources–if these 

emission reduction measures can’t in any meaningful way contribute to the attainment or 

maintenance of the 2008 ozone NAAQS for a particular area, the EPA should not use these 

Subpart 2 requirements for areas where it does not need to. 

Response: While the EPA did consider placing some areas only under the planning requirements 

of subpart 1, the EPA ultimately determined that such an approach was not its preferred approach 

for the 2008 ozone NAAQS. Instead, the EPA determined that classifying all areas under subpart 

2 and using the Percent Above The Standard (PATS) approach to translate Table 1 in section 

181(a) was the most appropriate option for addressing nonattainment for the 2008 ozone 

NAAQS. Under this approach, a majority of initial nonattainment areas were be classified as 

Marginal. The Marginal classification provides as much, if not more, flexibility for areas than 

would subpart 1. For example, a Marginal area is not required to submit an attainment 

demonstration while subpart 1 requires such a plan. For areas that are close to the standard and 

likely to attain within 3 years, an attainment demonstration could be a costly and likely 

unnecessary burden. We further note that the planning and control requirements that the 

Commenters believed were not flexible do not apply in Marginal areas. Further, all of the initial 

nonattainment areas classified as Moderate or higher for the 2008 ozone NAAQS are already 

subject to those requirements for purposes of the 1997 ozone NAAQS.

Furthermore, we disagree with the Commenters who suggest that areas would be able to attain 

the standard more expeditiously under subpart 1. As an initial matter, under both subparts, states 

are required to ensure that areas attain the NAAQS as expeditiously as practicable. Furthermore, 

the initial maximum statutory attainment date under subpart 1 is 5 years, while for Marginal 

areas, which will be the classification for most areas for the 2008 ozone NAAQS, it is 3 years. 

Regardless, under both subparts, states are required to ensure that areas attain the NAAQS as 

expeditiously as practicable.

For areas classified as Moderate or Serious, with a maximum attainment date under subpart 2 of 

6 or 9 years respectively, again subpart 1 does not necessarily set a shorter maximum attainment 

date. We note that the 5 year limit under subpart 1 is only binding if the EPA determines it is 

consistent with expeditious attainment. Subpart 1 allows the EPA to approve attainment 

deadlines up to 10 years from designation based on a demonstration by the state that a deadline 

longer than 5 years is as expeditious as practical considering the severity of nonattainment and 

availability and feasibility of pollution control measures. 

While it is true that subpart 1 would provide a shorter maximum attainment date for areas 

classified as Severe or Extreme, we note that under the court’s decision in South Coast, the 

EPA’s ability to place such areas solely under the planning provisions of subpart 1 is untested. 

Under the classification scheme for the 2008 ozone NAAQS, the lowest design value for an area 

classified as Severe is 0.113 ppm, which is well above the 0.090 level that the Court in South 

Coast indicated was the line between where the EPA had discretion to place areas in subpart 1 
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and where it did not have such discretion.30 Subpart 2 provides areas classified Severe or 

Extreme more than the 10 years maximum attainment date which, may be more appropriate for 

these areas given the severity of their ozone nonattainment problem.

With regard to comments that classification under subpart 1 would allow for coordinated 

planning and/or synchronized attainment dates where there are multiple nonattainment areas in 

the state, we note that under subpart 1 (as under subpart 2) areas are required to attain the 

NAAQS as expeditiously as practicable. Thus, subpart 1 does not allow a state to synchronize 

the attainment date for multiple areas unless the state could show that date is as expeditiously as 

practicable for each individual area. That means that the state would not be able to provide a 

longer attainment date for an area in order to take advantage of measures that would be 

implemented over a longer period if there are short-term emission reductions that are practicable 

and would result in an earlier attainment date. Moreover, we note that subpart 2 does not prevent 

the state from considering synchronization. The state could request a voluntary reclassification 

for an area, particularly if the area cannot practicably attain by the attainment date for its initial 

classification. Similarly, since all areas are required to attain as expeditiously as practicable, a 

state should consider whether areas with a “higher” classification might be able to attain more 

quickly. These provisions allow a state to synchronize attainment dates to the extent the date 

selected for areas is “as expeditiously as practicable.” 

To the extent the bulleted list of points provided in the letter from Commenter 0140 is not 

responded to above, we note the following:

To the extent that the Commenter is urging that, areas be placed solely under subpart 1 because 

subpart 1 provides more flexibility, we note that the Court in South Coast rejected the EPA’s 

approach to placing areas under subpart 1 in the Phase 1 Rule on the basis that the Act does not 

allow the requirements of subpart 2 “to be stripped away” on the basis that other provisions 

would allow attainment to be achieved more efficiently. 472 F.3d at 894.

It is true that the major source threshold is lower for areas classified under subpart 2 at the higher 

classifications than for those areas subject solely to subpart 1. However, for the lowest 

classifications of Marginal and Moderate, where the design values are less than 0.100 ppm, the 

major source threshold is the same as under subpart 1 – 100 tpy. It is also true that under subpart 

1, the offset ratio applicable to sources subject to NNSR (1 to 1) is lower than under subpart 2. 

However, the offset ratio is only slightly different – 1.1 to 1 in Marginal areas and 1.15 to 1 in 

Moderate areas. We do not believe that difference alone is a sufficient justification for placing 

areas solely under the planning provisions of subpart 1, particularly in light of the court’s holding 

in South Coast. As noted above, the EPA’s ability to place areas solely under subpart 1 for areas 

classified as Marginal and areas classified as Moderate with a design value less than 0.090 ppm 

 

30 The same is true for all areas classified under the 2008 ozone NAAQS as Serious as the lowest 

design value for such an area is 0.0100 ppm and for many areas classified as Moderate, which 

includes areas with a design value no lower than 0.086 ppm and less than 0.100 ppm.
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is untested.

The Commenter also raises several points regarding transport. We have addressed the issue of 

the relationship between transport and the nonattainment area planning provisions in section M.

3. Flexibility

Comment: Commenters (0149, 0150, 0152, 0153 and 0169) generally supported the EPA's 

efforts to provide flexibility to states in implementing the most recent ozone standard, while 

ensuring progress toward clean air.

Commenters (0163, 0167, 0169 and 0177) advised the EPA to be certain that any flexibility 

provided in the proposed rule is permissible under the CAA and existing case law to prevent 

further delay in implementing the 2008 standards. 

Commenter (0146) stated that, the NESCAUM states are concerned with the inequities that 

would result if the EPA were to allow new ozone nonattainment areas, as well as areas that 

should be designated nonattainment for the ozone NAAQS but are not, to be excused from their 

basic CAA obligations. Commenter (0146) stated that, it would place citizens in those areas as 

well as in downwind areas, at a public health disadvantage and it would also provide an 

unwarranted economic advantage to those areas over existing nonattainment areas. 

Commenter (0180) urged the EPA to abandon this latest round of attempts to avoid the specific 

measures provided by Congress in title I, part D, subpart 2 of the CAA, and instead to finalize 

implementation rules that conform to the statutory directives of the Act to address the nation’s 

ozone problems. Commenter (0180) stated that, the EPA should strive to apply the statutory 

requirements to the 2008 ozone NAAQS, not replace them. Commenter (0180) stated that, the 

EPA must make every effort to resolve uncertainty in favor of stronger public health safeguards 

and cited two cases. Commenter (0180) stated that, as the SCAQMD court and others have 

explained, it is not permissible for the EPA to pursue interpretations of the Act in an effort to 

maximize its own discretion “because the clear intent of Congress in enacting the 1990 

Amendments was to the contrary.” Id. at 895. 

Response: The EPA appreciates the Commenters’ comments regarding flexibility. In the 

proposed rule, we explored several mechanisms for providing flexibility to states in 

implementing the 2008 ozone NAAQS and the previous revoked ozone NAAQS. In some cases, 

were are finalizing those approaches. We are also not finalizing other proposed approaches due 

to concerns the Commenters raised regarding their legality. In other cases, more time is needed 

to assess whether such flexibility is consistent with the CAA. 
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3.0 What is the EPA proposing to address anti-backsliding issues related to transition 

from the 1997 ozone NAAQS to the 2008 ozone NAAQS?

A. Revocation--general 

The EPA did not receive any relevant comments on this section of the proposal preamble.

B. Transition from the 1-Hour to the 1997 Ozone NAA

The EPA did not receive any relevant comments on this section of the proposal preamble.

C. Nonattainment NSR

The EPA did not receive any relevant comments on this section of the proposal preamble.

D. Section 185 Fees

The EPA did not receive any relevant comments on this section of the proposal preamble.

E. Contingency Measures Requirement

The EPA did not receive any relevant comments on this section of the proposal preamble.

F. What is the EPA proposing regarding anti-backsliding requirements for the 1-hour 

and 1997 ozone NAAQS?

The EPA did not receive any relevant comments on this section of the proposal preamble.

G. Timing of 1997 Ozone NAAQS Revocation and Related Anti-Backsliding 

Requirements

1. Support revocation of the 1997 Ozone NAAQS 

Commenters (0132, 0143, 0145, 0146, 0153, 0154, 0158, 0159, 0166, 0169, 0173 and, 0179)

generally supported the EPA's proposal to revoke the 1997 Ozone NAAQS.

Commenter (0153) stated it makes little sense to be concerned about a standard that has been 

superseded by a newer, more stringent standard. Commenter (0154) added that if the EPA is 

delayed, for any reason, in publishing the final SIP requirements Rule, the EPA should process 

the revocation separately so that states can move forward and focus resources on the current 

NAAQS. Commenter (0158) agreed that it makes sense to revoke outdated and duplicative 

requirements because a full revocation will allow the states and local areas to efficiently focus 

their resources on planning for attainment of the current and stricter 75-ppb standard, and 

facilitate a smoother transition to the new standard for states and affected sources. Commenter 

(0179) stated this will ensure that only one ozone NAAQS, the more protective 2008 ozone 

NAAQS, applies for implementation purposes. 

Response: The EPA agrees that revoking the 1997 NAAQS and specifying adequate antibacksliding provisions appropriately allows states with nonattainment areas to focus planning 

efforts on the current, and most health-protective, ozone NAAQS while retaining, as appropriate,
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the unmet requirements for areas designated nonattainment when the previous NAAQS was 

revoked.

2. Do not support revocation of the 1997 Ozone NAAQS 

Commenter (0180) stated that the EPA should not revoke the 1997 8-hour ozone standard. 

Commenter (0180) stated that, while SCAQMD may have affirmed the EPA’s authority to revoke 

a NAAQS, the EPA still must provide a rational basis for doing so. Commenter (0180) stated 

that, for both the 1-hour ozone standard and the 1997 8-hour standard, attainment of these 

standards is still critical to providing the public health and welfare protections promised by the 

Act. Commenter (0180) stated that the EPA’s suggestion that resources should be focused on 

attaining the 2008 standard makes no sense since attainment of the 1997 standard will advance 

progress toward the 2008 standard and ensures that such progress will be made sooner rather 

than later. 

Commenter (0180) stated that the EPA’s proposal is irrational because it would waive key 

requirements for extreme nonattainment areas under the 1997 standard before the deadline comes 

due. Commenter (0180) stated that the EPA’s proposal unravels the CAA structure starting with 

the obligation to make the attainment determination required under sections 179 and 181 and the 

approach allows areas to avoid triggering more stringent control measures by resetting the clocks 

for bump ups. Commenter (0180) also stated that another generation of ozone standards is likely 

to be adopted in the near term and the EPA’s proposal suggests that it will seek to revoke the 

2008 standard just as areas are beginning to implement it. Commenter (0180) stated that this is 

not the course that Congress intended and cited Whitman at 531 U.S. at 485 (holding that 

Congress intended Subpart 2 to govern implementation of ozone standards “far into the future” 

and that Congress’ plan for ozone areas “was not enacted to be abandoned the next time the EPA 

reviewed the ozone standards”). 

Commenter (0180) stated that the EPA must explain the specific problems caused by retaining 

the 1997 (and 1-hour) ozone standard and tailor the solutions to address those specific problems, 

citing Burlington Truck Lines, Inc. v. United States, 371 U.S. 156, 168 (1962) (holding that 

agency must articulate a “rational connection between the facts found and the choice made”). 

Commenter (0180) stated that claims regarding the need for flexibility or discretion to tailor 

requirements to individual areas do not provide a reasonable justification, citing SCAQMD, 472 

F.3d at 895 (holding that “EPA’s interpretation of the Act in a manner to maximize its own 

discretion is unreasonable because the clear intent of Congress in enacting the 1990 

Amendments was to the contrary.”). 

Response: The EPA disagrees with the commenter’s arguments that EPA should not revoke the 

1997 ozone standard. The EPA also disagrees with the commenter’s statement that this is not a 

rational approach. The commenter does not address the CAA’s directive that the EPA re-evaluate 

the NAAQS periodically, and promulgate new NAAQS as appropriate. The promulgated 2008 

NAAQS is the current approved NAAQS for ozone. CAA section 172(e) applies when a 

NAAQS is relaxed, but that does not mean that Congress intended to preclude the EPA from 

applying its principles to prevent backsliding after replacing an existing standard with a more 
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stringent one. In this rulemaking the anti-backsliding program that accompanies and 

complements revocation is consistent with that which the D.C. Circuit approved when the EPA 

revoked the 1-hour standard. South Coast Air Quality Management District v. EPA, 472 F.3d at 

899. The EPA continues to make determinations for the 1997 8-hour ozone standard to the extent 

they are necessary to implement anti-backsliding requirements – for example for contingency 

measures. The EPA’s record in implementing the anti-backsliding requirements after revocation 

of the 1-hour standard demonstrates that revocation did not result in backsliding. Moreover, now 

the EPA and the states must further update and strengthen requirements. Similar arguments 

support revocation now as when the D.C. Circuit approved the approach in the South Coast case. 

Now there exist both a new NAAQS and two prior NAAQS. Evidence shows that there has been 

continuous improvement in air quality, but experience also shows that more is needed. Allowing 

the EPA to rationalize and integrate prior requirements with new goals facilitates effective and 

timely planning and controls, rather than imposing burdensome intermediate requirements left 

over from obsolete standards. The anti-backsliding measures introduced upon revocation of the 

1997 ozone NAAQS ensure the same level of protection provided by control measures 

established for the 1997 ozone NAAQS, while enabling areas, where possible, to focus planning 

efforts on meeting the more protective 2008 ozone NAAQS. This approach addresses the 

specific problem of duplicative efforts for different ozone NAAQS. The strong anti-backsliding 

provisions in 40 CFR 51.1105 will ensure that the protection provided by controls already 

adopted to attain the previous NAAQS will continue until an area attains the 2008 ozone 

NAAQS, and will also ensure that there will be no delay in attaining the 1997 ozone NAAQS. 

Furthermore, the provisions of section 51.1105 continue to require areas to expeditiously achieve 

emissions reductions for the revoked NAAQS. Since it is impossible to attain the 2008 ozone 

NAAQS without also attaining the 1997 ozone NAAQS, formal retention of the 1997 NAAQS 

would be superfluous from the standpoint of protection of health. The 2008 ozone NAAQS 

constitutes a significant strengthening of the 1997 NAAQS, which requires the area to achieve 

additional reductions as expeditiously as practicable. The EPA, in retaining for the 2008 ozone 

NAAQS the anti-backsliding structure that the D.C. Circuit previously endorsed for revocation 

of the 1-hour ozone standard, has taken into account the new and additional responsibilities 

placed on states, and the weight of two levels of anti-backsliding requirements. 

The EPA agrees with the commenter that the adopted revocation approach means that the 1997 

NAAQS would be revoked before the statutory maximum attainment date for areas classified as 

Severe and Extreme for the 1997 ozone NAAQS. We believe that Congress understood this 

possibility when it amended the CAA in 1990 to require the EPA to review each NAAQS every 

5 years. Similarly, Congress also recognized that areas with more significant ozone problems 

would need more time to attain the standard, and gave these areas more time to attain the 

standard, with timeframes for attainment largely beyond the 5-year timeframe required for 

review of the NAAQS. The EPA does not agree with the commenter’s characterization of 

revoking the NAAQS. The commenter’s argument does not address the fact that the old standard 

has been supplanted by a more protective standard, and that the EPA’s anti-backsliding 

requirements, combined with the CAA’s new obligations to achieve the more stringent 2008 

ozone NAAQS as expeditiously as practicable, effectively fulfill the function of the prior 

attainment date. In addition, the EPA notes that the attainment demonstration for the prior 
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standard is retained as an anti-backsliding measure. Moreover, failure to attain the new standard 

by the applicable attainment date for that standard will result in reclassification to a higher 

standard as appropriate. 

For these reasons, and consistent with the anti-backsliding regime previously endorsed by the 

D.C. Circuit for the transition from the 1-hour to the 1997 ozone NAAQS, the EPA believes that 

the revocation and associated anti-backsliding measures for the 2008 ozone NAAQS provide the 

appropriate way to move toward attaining the more protective standards in a timely and effective 

manner, while ensuring that progress made under previous ozone NAAQS is not lost. 

3. Comments regarding the date of revocation 

Commenters (0143, 0159, 0169 and 0177) supported the revocation of the 1997 ozone NAAQS 

as soon as possible to eliminate duplicative SIP development efforts. Commenter (0169) stated 

that revocation of a standard should occur upon finalization of a new standard and at no point 

should states be required to juggle two (or three) standards at the same time for the same 

nonattainment area as this largely amounts to a paperwork exercise that is a huge resource 

burden without air quality benefits. Commenter (0177) asserted that the EPA’s transition and 

anti-backsliding proposals will be more equitably applied and more protective of air quality if the 

effective date of the implementation rule and the revocation date of the 1997 NAAQS occur 

together.

Commenter (0143) stated that if the effective date of the final rule is not the date the final SIP 

Requirements Rule is published in the Federal Register, then the revocation of the 1997 ozone 

standard should take effect on the effective date of the final rulemaking. Commenter (0143) also 

agreed the anti-backsliding provisions in the CAA should be adequate to ensure areas continue to 

work toward attainment if not achieved prior to revocation of the 1997 ozone standard. 

Commenter (0159) stated they could support the use of the date of initial designation to nonattainment nationwide. Commenter (0159) noted that using this revocation date would lead to the 

creation of more legacy nonattainment areas that would be subject to anti-backsliding 

requirement. 

Commenter (0177) stated the EPA’s transition and anti-backsliding proposals will be more 

equitably applied and more protective of air quality if the effective date of the implementation 

rule and the revocation date of the 1997 NAAQS occur together. 

Response: We disagree with commenters that recommended that the EPA revoke the 1997 

ozone NAAQS at an earlier date. We believe that revoking the 1997 ozone NAAQS prior to the 

establishment of clear anti-backsliding requirements would create a gap when taking action on 

plans submitted by states. The EPA believes and the court has endorsed that backstops to prevent 

backsliding from the protections provided by measures implemented for a previous NAAQS 

must be in place before the EPA can revoke that NAAQS. The EPA, upon considering the 

comment on the effective date of revocation, has clarified in the final rule that the 1997 ozone 

NAAQS will be revoked on the rule’s effective date as set forth in the Federal Register. That is, 
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the 1997 ozone NAAQS will be revoked 30 days after publication of the final rule in the Federal 

Register.

Comment: Use of most recent monitoring data

Commenters (0143, 0146, 0163, 0167, 0170 and 0177) stated the EPA should modify the 

proposed rule to ensure all areas designated as attainment that are currently violating the 2008 

NAAQS are subject to CAA nonattainment provisions. Commenters (0143, 0146 and 0163) 

stated the EPA should use 2012 monitoring data to designate nonattainment areas. 

Commenter (0143) stated the EPA appears to be allowing some areas in the Midwest to be 

designated attainment/unclassifiable, even though if the same criteria used to designate areas in 

Pennsylvania nonattainment were applied to these Midwest areas, the Midwest areas would be 

designated nonattainment areas for the 2008 ozone NAAQS. Commenter (0143) stated EPA 

should designate nonattainment areas using the most recent state certified monitoring data and 

consistently apply the criteria for designating ozone nonattainment areas across the country, in 

order to improve air quality and public health and for equity. 

Commenter (0146) stated that part of ensuring against backsliding for the 2008 ozone NAAQS is 

ensuring that areas that violate the ozone NAAQS are designated as nonattainment and are 

required to achieve the emissions reductions necessary to meet and maintain the NAAQS. 

Commenter (0170) urged the EPA to utilize the most up-to-date and reliable air quality 

monitoring data in making area designations or re-designations for the 2008 ozone NAAQS and 

cited Southwestern Pennsylvania Growth Alliance v. Browner, 121F.3d106, 115-16 (3d Cir. 

1997) (upholding the EPA’s decision to deny re-designation based on newly-available data). 

Response: These comments focus on the designation process, and are thus beyond the scope of 

this rulemaking. Nevertheless, EPA provides a brief response for the benefit of the commenters.

The EPA uses a five-factor analysis to designate areas and applies the same process to all areas 

taking into consideration the specific circumstances of each area under consideration. In the 

action of designating areas for the 2008 standard, the EPA set forth its analysis for each area 

designated nonattainment and also responded to comments suggesting that the EPA treated areas 

inconsistently. (77 FR 30088; May 21, 2012 and EPA-HQ-OAR-2008-0476-0675.) The EPA 

also replied to similar claims in responding to 29 petitions for reconsideration of the rule 

(http://www.epa.gov/airquality/ozonepollution/designations/2008standards/petition.htm). 

The issue of the data EPA used to designate areas for the 2008 ozone NAAQS was fully 

addressed in the record for the designations, including EPA’s responses to 29 petitions for 

reconsideration. This rulemaking is not the appropriate place to address this issue. As noted, the 

EPA addressed claims of inconsistency raised during the designation process at the time it issued 

final designations and also in responding to petitions for reconsideration. 
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4. Redesignation after revocation

Commenter (0169) partly agreed with the EPA's decision to not take action to designate or 

redesignate areas for a standard after the standard has been revoked, but believes that if a state

has submitted a request for a clean data determination and/or a redesignation request for an area, 

the EPA is obligated to act to redesignate that area even after the standard has been revoked. The 

commenter further indicated that state submittals are often not acted on in a timely manner. The 

EPA should be applauded for the notion of not redesignating an area for a revoked NAAQS 

which would be designated nonattainment for a subsequent NAAQS. This proposal should 

reduce the burden to states and EPA. An issue arises, however, for areas which are designated 

nonattainment for a previous revoked NAAQS (or unclassifiable) and is designated attainment 

for the current NAAQS. The Department encourages the EPA to fully consider the ramifications 

of this decision. 

Response: Where possible, the EPA will endeavor to act on any rulemaking for the 1997 ozone 

NAAQS that would impact the status of anti-backsliding requirements for that NAAQS prior to 

the revocation of that standard. It should be noted that a clean data determination (CDD)

suspends only the requirement to submit attainment-related planning elements. The EPA has 

consistently taken the position that, after revocation of a NAAQS, the EPA cannot redesignate an 

area for the revoked NAAQS, nor formally change an area’s legal designation for a NAAQS that 

no longer exists. However, the EPA can continue to determine whether the area’s air quality 

meets the level of the prior NAAQS in order to make appropriate determinations related to antibacksliding requirements for the revoked NAAQS.

In section IV.C of the final rule the EPA addresses the appropriate requirements for areas which 

are designated attainment for the current NAAQS but which were designated nonattainment for a 

prior NAAQS at the time of revocation of the 1997 NAAQS. 

5. Continued attainment after revocation

Commenters (0163, 0167 and 0177) stated the EPA should modify the proposed rule to ensure 

all areas designated as attainment for the 2008 ozone NAAQS that are currently violating that 

standard are subject to CAA nonattainment provisions. 

Commenter (0163) stated EPA should rescind the clean data determinations for certain areas and 

reclassify them with respect to CAA section 18l(b)(2) and subpart 2 before revoking the 1997 

NAAQS. The commenter continued stating that many areas with 1997 ozone NAAQS clean data 

determinations have 2012 ozone data that indicates continued nonattainment. EPA should 

rescind the clean data determinations for these areas and reclassify them with respect to CAA 

section 181(b)(2) and subpart 2 before revoking the 1997 NAAQS. This approach would 

recognize the severity of the ozone problem in these areas and protect the public health of 

persons living in these areas. (0163)

Commenter (0167) indicated that the OTC states request the EPA to exercise its authority under 

CAA section 107(d)(3) to establish revised designations for areas now classified as “attainment”, 
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but violating the 2008 NAAQS based on current ozone design values. The revocation of the 1997 

ozone NAAQS for these areas should be linked to the date that the revised designations become 

effective. This will ensure that CAA nonattainment provisions apply to all areas currently 

violating the 2008 NAAQS and ensure the appropriate level of relief from anti-backsliding and 

other requirements is correctly applied to those areas that warrant such treatment. 

Response: We disagree that the EPA must consider air quality data that was not available in 

sufficient time for the initial designations and redesignate areas based on that data for purposes 

of determining appropriate anti-backsliding requirements prior to revoking the 1997 ozone 

NAAQS.

As appropriate, the EPA will address air quality management issues relating to monitored 

violations of the 1997 ozone standard in separate rulemakings or other proceedings. Even after 

revocation of the 1997 ozone NAAQS, the EPA retains the ability to make or rescind clean data 

determinations (CDDs) where appropriate to implement anti-backsliding requirements. The EPA 

agrees that several areas with CDDs for the 1997 ozone NAAQS briefly exceeded that NAAQS. 

However, before the EPA could take action on those areas, their data showed them to be back in 

attainment with the 1997 ozone NAAQS. One area, the New York-Northern New Jersey-Long 

Island (NY-NJ-CT) nonattainment area, has continued to violate the 1997 ozone NAAQS after 

EPA had issued a CDD. Accordingly, the EPA proposed to rescind the CDD for that area on 

May 15, 2014 (79 FR 27830). 

H. What are the applicable requirements for anti-backsliding purposes 

following the revocation of the 1997 ozone NAAQS?

1. General

Commenters (0172, 0179) supported the proposal regarding anti-backsliding requirements during 

transition to the 2008 ozone NAAQS. Other commenters, as indicated in the subsections that 

follow, expressed concerns about specific anti-backsliding provisions. These more specific

concerns are addressed individually.

Response: EPA appreciates the comments in support of the proposal, and acknowledges the 

range of views expressed by commenters regarding specific anti-backsliding provisions. As a 

general matter the EPA has attempted to consider the circumstances of the areas subject to antibacksliding requirements, including the timing and nature of those requirements arising from 

failure to attain prior standards relative to the requirements for the current standard. Factors we 

have taken into account include:

1) Almost a decade has passed since the EPA first adopted and implemented the antibacksliding approach implemented when the 1-hour ozone NAAQS was revoked. The 

EPA first adopted anti-backsliding provisions in 2004 and revised them in accordance 

with the 2006 South Coast decision. Years later many areas have attained the 1-hour 

and 1997 standards and have been redesignated to attainment. Other areas are much 

closer to meeting the 1997 standard. We have learned from our experience with anti-
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backsliding, and have attempted to coordinate old and new requirements more 

effectively.

2) This is the second time anti-backsliding requirements have been imposed, creating an 

additional layer of hold-over requirements for some areas. Areas facing these antibacksliding requirements are identified in the appendices of the final rule. Note that

progress will continue to be made while the areas are subject to a more stringent 2008 

standard, with near-term implementation requirements.

3) There is a difference between the standard being revoked with this implementation 

rule versus the standard revoked by the implementation rule for the 1997 ozone 

NAAQS. The 1997 ozone NAAQS differed in both form (8-hour versus 1-hour) and 

level (0.08 ppm versus 0.12 ppm) from the 1-hour standard. Anti-backsliding rules 

developed for implementation of the 1997 ozone NAAQS had to take these 

differences into account. This time, the form of the standard replacing the 1997 

NAAQS is the same, but at a lower level (0.075 ppm versus 0.08 ppm). Thus it is 

mathematically impossible to attain the 2008 ozone NAAQS without first attaining 

the 1997 ozone NAAQS.

4) Because of the similarity in form (8-hour average) of the standard, we have examined 

potential ways to integrate anti-backsliding requirements with the requirements of the 

current standard, such as with merging relevant attainment planning requirements for 

the revoked and current standards. 

5) The submission dates for certain 2008 attainment plans (July 20, 2015) and 

attainment dates for 2008 Marginal areas (July 20, 2015) are more proximate in time 

to the publication of the final SIP Requirements Rule than were the Phase 1 and 

Phase 2 rules implementing the 1997 ozone NAAQS.

6) Both states and the EPA are facing resource shortages.

7) The 2008 ozone NAAQS does not relax ozone standards – it makes them more 

stringent. Accordingly, nonattainment areas for the 1997 and 1-hour standards must 

remain on a one-way route to attainment – we are neither relaxing standards nor 

requirements with each subsequent ozone NAAQS.

No system of laws and requirements can work by simply piling new requirements on top of old 

without effort to integrate and harmonize them. 

Comment: Accountability for Previous Clean Air Act Control Programs

Commenter (0164) stated there should be better clarity on accountability for anti-backsliding 

requirements and revisit the onerous rules that seem to forever hold a region to a past set of 

emission reduction control programs. The commenter added their perception that federal 

emission reduction control programs are not held to the same standards as locally implemented 

programs. Examples include the ASM consideration in the proposal and Stage II Vapor 

Recovery. A region should not be held accountable for a set of emission reduction control 

programs that were at one time incorporated into a past SIP. The new SIP should be able to stand 

on its own merit and reset the list of necessary control strategies for that timeframe and set of 

requirements. 
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Response: EPA’s anti-backsliding approach establishes a clear framework for ensuring 

continued protection for air quality while providing relief, where appropriate, from potentially 

onerous and unnecessary requirements arising from failure to attain revoked standards so that 

planning efforts can focus on attaining current, more protective standards. 

The EPA disagrees with the commenter that federal emission control programs are not held to 

the same standard as locally implemented programs. SIP-approved control measures, whether 

federal programs or locally implemented measures, may not be modified unless the modification 

meets the requirements of CAA section 110(l) and, if applicable, section 193. For purposes of 

anti-backsliding, the implementation of new Stage II control programs are no longer mandatory 

because the EPA has determined under the statutory provisions of section 202(a)(6) that another 

federal program, onboard refueling vapor recovery (ORVR) technology, is in widespread use, 

rendering Stage II controls largely redundant. However, in an area where a Stage II control 

program is already adopted into the SIP, it can only be removed from the SIP if the conditions of 

CAA sections 110(l) and 193 are met. Therefore, this federal measure is subject to the same 

treatment as any locally implemented SIP-adopted control measure.

Comment: Attainment Planning Requirements

Commenter (0151) stated that no attainment planning requirements should apply once the 1997 

NAAQS has been revoked (regardless of an attainment re-designation or a clean data 

determination). The commenter supposed that proposed §51.1118 would suspend attainment SIP 

planning requirements in a nonattainment area only upon a determination that the area has 

attained the ozone NAAQS. However, the commenter further believed that if the area has failed 

to attain the standard, the EPA suggests that under South Coast, its hands are tied and SIP 

planning requirements are not suspended. The commenter believed that no attainment planning 

requirements should apply once the 1997 NAAQS has been revoked (regardless of an attainment 

re-designation or a clean data determination). First, Section 172(e) applies to control 

requirements and not State “planning requirements.” Second, commenter (0151) asserted that 

South Coast’s applicability to SIP Planning Requirements can be narrowed because the Court 

was faced with two distinct standards whose form and stringency varied. Here, the form of the 

2008 NAAQS is the same as the 1997 ozone standard, but the EPA made the standard more 

protective. Therefore, it would be reasonable for the EPA to determine that the SIP planning 

requirements are aligned under the standards and SIP planning for the 1997 standard transitions 

into planning for the 2008 NAAQS, in order to prevent the unnecessary additional use of federal 

and state resources when the EPA has modified the prior NAAQS to make it more protective. 

Revocation of a standard should result in State authorities and EPA moving on to new challenges 

instead of perpetuating SIP planning for obsolete standards. In fact the new standards are simply 

a more stringent health standard for the prior standard. Thus, in contrast, perhaps to the EPA’s 

current SIP process for the one-hour NAAQS examined in the South Coast, there is no point in 

maintaining the SIP planning requirements for the 1997 and soon-to-be 2008 obsolete versions 

of that NAAQS. 

Response: The EPA agrees that the transition from the 1997 ozone NAAQS to the 2008 ozone 

NAAQS calls for a re-evaluation of the provisions necessary to protect against backsliding and 
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ensure continued progress toward achieving healthy air quality. However, we do not agree that 

South Coast v. EPA has limited application to informing appropriate anti-backsliding 

requirements for a revoked 1997 NAAQS simply because the 2008 NAAQS has the same form 

as the 1997 NAAQS. With only one exception, the seventeen “applicable requirements” that will 

be listed in new 40 CFR 51.1100(o) are all control requirements, consistent with the reasoning of 

South Coast v. EPA. To the extent that any of these control requirements have not been 

implemented in a 1997 nonattainment area by the time the 1997 NAAQS is revoked, consistent 

with South Coast v. EPA the state must ensure that measures no less protective than these 

controls are adopted into the SIP and implemented, if applicable. The one applicable requirement 

that involves both planning and control elements is the attainment demonstration requirement. 

Since the attainment demonstration is part of the basis for establishing that the RACM 

requirement (a control requirement consistent with South Coast) is satisfied, the EPA believes it 

is appropriate to retain this as an applicable anti-backsliding requirement to ensure timely 

progress toward attainment of the 1997 NAAQS, especially for areas classified in the highest 

classifications where the statutory attainment dates for the 1997 NAAQS extend well into the 

future (e.g., 2019 for Severe and 2024 for Extreme areas). The EPA encourages states to 

synchronize their planning and emissions control efforts for attainment of the 2008 ozone 

NAAQS with any unfulfilled anti-backsliding requirements associated with the revoked 1997 

ozone NAAQS. As a reminder, a clean data determination for the 1997 ozone NAAQS can 

suspend the associated attainment demonstration requirement for as long as the area continues to 

attain the 1997 NAAQS.

Comment: RACM and other control requirements

Commenter (0180) stated that several control requirements that apply to areas designated 

nonattainment under the 1-hour and 1997 ozone standards should be included in 40 CFR § 

51.1100(o). Commenter (0180) stated that EPA’s lack of listing RACM must have been an 

oversight since these are clearly control measures covered by the “principles” of subsection (e) 

of the same section. In addition, commenter (0180) stated that the following control requirements 

must be retained: (1) obligation to adopt “other control measures” as necessary for attainment 

under section 172(c)(6); (2) conformity; and (3) contingency measure requirements under section 

182(e)(5) for Extreme nonattainment areas relying on a “black box”. Commenter (0180) stated 

that the rationale for including these measures is the same as that for other contingency measures 

as outlined in South Coast. Commenter (0150) requested that the EPA clarify whether the 

contingency measures that are included in the anti-backsliding provisions would include the 

Section 182(e)(5) contingency measures

Response: The EPA agrees in part with the commenter, that it is appropriate to list both RACM 

and section 182(e)(5) contingency measures as “applicable requirements” in the final rule in 

section 51.1100(o). RACM is a component of the attainment demonstration, which the EPA did 

list in the proposal, and is a requirement of the CAA. The EPA reviews each SIP submission 

from a state to ensure that sufficient information is provided for the EPA to determine whether 

the state has adopted all RACM necessary for attainment as expeditiously as practicable and 

provided for implementation of those measures as expeditiously as practicable. For areas 

remaining in nonattainment for the 1997 ozone NAAQS and designated nonattainment for the 
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2008 ozone NAAQS, the EPA does not believe that revocation of the NAAQS should halt or 

delay the planned implementation of control measures. These measures, while adopted pursuant 

to the 1997 ozone NAAQS, will also assist the areas in attaining the 2008 ozone NAAQS. 

Similarly, for Extreme areas relying on CAA section 182(e)(5), the EPA agrees that the 

contingency measures required for that program should be held to the same requirements as 

contingency measures for sections 172(c) and 182(c) of the CAA. Thus the EPA is adding 

182(e)(5) contingency measures to the list of applicable requirements in 51.1100(o).

However, the EPA does not agree with the commenter that conformity needs to be retained as an 

applicable requirement for a revoked standard. Transportation and general conformity are

retained as requirements for all areas designated nonattainment for the 2008 ozone NAAQS. For 

areas designated attainment for the 2008 ozone NAAQS, these areas are meeting the most 

stringent, health-protective NAAQS and thus have no remaining conformity requirements 

because they are designated attainment for the 2008 ozone NAAQS and the designations for the 

1997 ozone NAAQS, which in the past triggered conformity requirements, no longer apply after 

the previous standard has been fully revoked. NRDC v. EPA (2014). Transportation and general 

conformity apply only in areas designated as nonattainment or redesignated to attainment with an 

approved CAA section 175A maintenance plan. (CAA section 176(c)(5)). Upon the effective 

date of the revocation of the 1997 ozone NAAQS the only relevant designation for ozone for 

conformity purposes will be an area’s designation for the 2008 ozone NAAQS.31 Areas that are 

designated attainment for the 2008 ozone NAAQS are not subject to transportation or general 

conformity requirements regardless of their designation for the 1997 ozone NAAQS at the time 

of revocation of that NAAQS. (CAA section 176(c)(5)). Similarly, “other control measures” 

necessary for attainment are already covered by the attainment demonstration, and cannot be 

removed without satisfying CAA section 110(l). 

Comment: Clean Fuels Fleet Program

Commenter (0127) stated that the Clean Fuels Fleet Program (CFFP) should not be retained as 

an applicable requirement for anti-backsliding purposes. Commenter (0127) stated that while the 

program originally applied in 22 metropolitan areas, most of those jurisdictions long ago opted 

out of the CFFP and some of the jurisdictions that still have the CFFP in their regulations are not 

enforcing it because the CFFP's fleet-specific emission standards have been overtaken by more 

stringent national and California standards over the years. Removing the requirement would have 

no impact on air quality generally and implementation of the 8-hour ozone NAAQS specifically 

 

31 The EPA revoked the 1997 ozone NAAQS for transportation conformity purposes only on 

May 21, 2012. (77 FR 30160), effective on July 20, 2013. The D.C. Circuit ruled (December 23, 

2014) that the EPA violated the CAA when it revoked the 1997 ozone NAAQS for purposes of 

transportation conformity only, while recognizing that it had previously upheld the EPA’s 

authority to revoke a standard in full. NRDC v. EPA (D.C. Cir. No. 12-1321, Dec 23, 2014). In 

this final rule, the EPA is fully revoking the 1997 ozone NAAQS for all purposes.
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because 23 years later the CFFP has become a vestigial organ of the 1990 amendments to the 

CAA. 

Response: We disagree with the comment and we are finalizing requirements specifying the 

CFFP as an “applicable requirement” for anti-backsliding purposes. Under section 182(c)(4) of 

the Act, states may opt out of the CFF program if they provide a substitute program that results 

in either as much or greater long-term emissions reductions. These substitute programs are also 

subject to this final rule’s anti-backsliding requirements. A number of areas that were included in 

the initial list of areas subject to the program requirements continue to be required to implement 

the program or a substitute measure because their classification for the 2008 ozone NAAQS is 

Serious or above, under section 246(a)(3) of the Act. Finally, areas not subject to the clean fuels 

fleet program requirements due to their classification for the 2008 ozone NAAQS can remove 

the program or substitute measure by meeting the applicable requirements described in section 

IV.D of the final rule. The specific requirement for any given area would depend on whether the 

area was initially designated as nonattainment or attainment for the 2008 ozone NAAQS and 

whether or not the area was nonattainment or maintenance for the prior 1997 or 1-hour ozone 

NAAQS. As a general matter, the CFF program continues to apply to existing covered fleet 

because these fleet are comprised of older vehicles. Finally, section 243(e) allows for 

replacement of CFF standards with CARB standards that the EPA determines are “in the 

aggregate at least as protective of public health and welfare.” EPA has yet to make that 

determination. 

Comment: Attainment Demonstration Requirement

Commenter (0150) requested that the EPA explain that its retention of the "attainment 

demonstration" as an anti-backsliding measure means, for states that already have an approved

demonstration, that the state must continue to implement its approved attainment demonstration, 

not that it must submit a new attainment demonstration. Commenter (0150) also requested that 

the EPA clarify that where an approved attainment demonstration for an Extreme area includes 

Section 182(e)(5) measures, whether the state must continue to implement those Section 

182(e)(5) measures as part of the anti-backsliding requirement for the attainment demonstration. 

Commenter (0178) stated that developing another attainment demonstration for the outdated 

1997 ozone NAAQS would be a paperwork exercise, and only divert limited Air Program 

resources from working toward achieving air quality benefits and attaining the more protective 

2008 ozone NAAQS. Commenter (0178) stated that the Air Program made a good faith effort to 

meet all its planning obligations for the 1997 ozone NAAQS, including an attainment 

demonstration, but few of them were approved by EPA, largely due to litigation surrounding 

federal interstate transport rules.

Response: The term “applicable requirements” for anti-backsliding purposes refers to any 

outstanding requirements that have not yet been adopted or approved into the SIP, or otherwise 

determined by EPA to be satisfied at the time of revocation of the standard, including the 

requirement for an attainment demonstration under Section 182(c)(2)(A), which may also 

include anticipated development of new control technologies under 182(e)(5). Any requirement 

for which EPA has approved the relevant SIP provision or made a determination that the 
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requirement has been satisfied is not an applicable requirement for which a new submission must 

be made. This does not mean, however, that implementation of these provisions may cease. Any 

provisions that have already been approved into the State’s SIP need not be re-submitted, but 

they must continue to be implemented until EPA approves a SIP revision. The final rule requires

an area subject to an outstanding planning requirement to address that requirement, but would 

allow, as appropriate, latitude for that planning requirement to be satisfied in conjunction with 

satisfaction of requirements for current standards. (For example, the emissions reduction 

measures included in 6-year RFP plan (2012-2018) for 2008 NAAQS Moderate and above areas 

may be sufficient to demonstrate attainment of the 1997 NAAQS by the Severe area attainment 

deadline of 2019.) We believe this approach will prevent delay in achieving emissions reductions 

as States transition to achieving the more stringent 2008 ozone NAAQS. We encourage, where 

possible and appropriate, that areas with planning requirements for both the 1997 and the 2008 

ozone NAAQS combine these into a single submittal.

Comment: Stage II vapor recovery

Commenters (0132, 0141, 0143, 0155, 0156 and 0157) stated that they support the exclusion of 

the Stage II vapor recovery program from the list of measures to be retained for anti-backsliding 

purposes. Commenters (0132, 0155 and 0157) stated that, given vehicle on-board refueling vapor 

recovery (ORVR) provides pollution reduction equivalent to Stage II control systems and the 

widespread use of ORVR, the use of Stage II control systems is not cost-effective and is a 

redundant system. Commenter (0143) stated that, although the proposed rule "would have no 

effect on the continuing independent CAA section 184(b)(2) requirement for OTR states to 

implement Stage II programs or measures capable of achieving emissions reductions comparable 

to those achieved by Stage II", nonetheless, the commenter supported the proposed revisions to 

the anti-backsliding rules.

Response: The EPA made a determination that ORVR was in widespread use which allowed the 

EPA to exercise its authority to waive the Stage II Vapor Recovery requirements for ozone 

nonattainment areas. See 77 FR 28772; May 16, 2012. Accordingly, it is no longer necessary for 

EPA to retain this control measure as an applicable requirement. The EPA developed guidance 

titled, “Guidance on Removing Stage II Gasoline Vapor Control Programs from State 

Implementation Plans and Assessing Comparable Measures,” (August 7, 2012)32, which provides 

suggestions to air quality management agencies how to exercise discretion in implementing the 

waiver in areas with SIP –approved Stage II programs. This guidance document provides both 

technical and policy guidance to the states on how to develop and submit an approvable SIP 

revision that requests removal/phase-out of an existing Stage II program. This guidance 

 

32 See “Guidance on Removing Stage II Gasoline Vapor Control Programs from State 

Implementation Plans and Assessing Comparable Measures,” August 17, 2012. This guidance 

can be accessed on the web at http://www.epa.gov/glo/pdfs/20120807guidance.pdf.
216

introduces methods and equations to calculate emissions reductions to demonstrate compliance 

with Section 110(l) and 193. 

Comment: Support alternative measures

Commenter (0173) stated that the EPA has repeatedly taken the position that the CAA allows 

alternative, not less stringent programs to satisfy anti-backsliding requirements in connection 

with transitions to newer, more stringent ozone NAAQS and cited the June 7, 2013 Brief for 

Respondents U.S. Environmental Protection agency et al., Medical Advocates for Healthy Air v. 

EPA, No. 12-73386 (9th Cir.) (defending EPA's authority to approve the San Joaquin Valley's 

not less stringent alternative to section 185 fees for the revoked 1-hour ozone NAAQS). 

Commenter (0173) requested that the EPA amend the proposed regulatory text to clearly allow 

alternatives that are not less stringent than nonattainment controls for anti-backsliding purposes 

and stated this change could be accomplished in at least two ways:

1. Amend the definition of "applicable requirements" at proposed 40 CFR

§ 51.1100(o) to define applicable requirements to include "alternative programs not less 

stringent than" the listed program requirements at proposed § 51.1100(o)(1 )-(15).

2. Amend the provisions specifying which areas are subject to anti-backsliding 

requirements to allow alternatives. A sentence could be added at the end of each of 

proposed § 51.1105(a)(l )(i), (a)(2), (a)(3)(i), and (a)(4)(i), to state: "Instead of the 

applicable requirements, the area may adopt and implement alternatives that are not less 

stringent than the applicable requirements." 

Response: We believe the application of section 172(e) principles to applicable section 185 antibacksliding requirements is an appropriate and reasonable use of the Administrator’s discretion 

to approve “not less stringent” controls. However, we did not propose and do not intend at this 

time to promulgate regulatory language to universally apply the “not less stringent” control 

authority to other specific applicable anti-backsliding requirements.

Comment: Do not support alternative measures

Commenter (0180) disagreed with the EPA’s proposal regarding section 172(e). Commenter 

(0180) stated that section 172(e) only applies to the replacement of a NAAQS with one that is 

less stringent. Commenter (0180) stated that South Coast Air Quality Management District

(SCAQMD) provides no support for the conclusion that Congress gave the EPA the legislative 

authority to rewrite the plain requirements of the Act when the EPA strengthens a national air 

standard. Commenter (0180) stated that the court concluded that “[a]ny area failing to achieve 

the equivalent of Congress’s chosen level of public health must be covered by Congress’s chosen 

prophylactic scheme.” Commenter (0180) stated that the EPA’s suggestion that the court in 

NRDC, 643 F.3d 311, did not prohibit the use of 172(e) to fashion equivalent alternatives (78 FR 

at 34213) is misleading because the court simply did not reach this legal issue. 
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Response: The EPA disagrees. South Coast upheld EPA’s authority to apply the principles of 

Section 172(e) in developing anti-backsliding measures that are no less stringent than those that 

applied under a NAAQS that was revised to make it more stringent. Further, NRDC declined to

prohibit alternative programs categorically, stating that “neither the statute nor our case law 

obviously precludes” an alternative program. See NRDC v. EPA, 643 F.3d 332 (D.C. Cir. July 

2011). 

Comment: Need to clarify transition requirements

Commenter (0178) stated the proposal is not clear how to develop SIP submissions that satisfy 

requirements for both the 1997 and 2008 ozone NAAQS especially for the case of the St. Louis 

area, which has requirements for RACT, RFP, an attainment demonstration, and other 

obligations associated with its Moderate classification for the 1997 NAAQS, yet only emissions 

inventory and emissions statement requirements associated with its Marginal status for the 2008 

NAAQS. The commenter believed that the preamble language references the April 30, 2004 final 

Phase 1 rule but does not explicitly state that the options provided in that rule are acceptable for 

transitioning from the 1997 to the 2008 ozone NAAQS. The Air Program supports options for 

addressing any remaining 1997 ozone NAAQS planning obligations that take into account the 

agency's previous efforts and move the St. Louis area forward toward the goal of attaining the 

2008 ozone NAAQS. This includes reasonable approaches such as submitting an early increment 

of progress plan toward the current ozone NAAQS (option 2 in the final Phase 1 rule). 

Response: With the language in the proposal we meant to indicate that planning requirements 

for the 2008 ozone NAAQS could be used to also address any unmet requirements under the 

1997 ozone NAAQS. Because the 1997 and 2008 ozone NAAQS share the same form but differ 

in stringency, plans developed to bring a nonattainment area into compliance with the more 

stringent 2008 ozone NAAQS would have the direct benefit of addressing attainment or 

maintenance of the 1997 ozone NAAQS in the process. However, it is also true that the 

fulfilment of any outstanding emissions control obligations associated with the 1997 NAAQS 

(such as RACT and RFP) will directly benefit attainment and maintenance of the 2008 NAAQS 

for areas classified Marginal, which have an attainment date of 2015.

Comment: Delayed requirements

Commenter (0180) stated that, in evaluating backsliding, the EPA must evaluate not only 

existing requirements in place in a SIP, but also requirements that are currently required but have 

not been put into place because of illegal delays on the part of states and/or EPA. Commenter 

(0180) stated that the EPA’s revocation of the 1997 ozone standard will cause backsliding if 

provisions, which currently should be in place but for illegal delays, are not implemented. 

Commenter (0180) provided examples for the Houston-Galveston-Brazoria and the Baltimore 

nonattainment areas with respect to the 1997 ozone NAAQS. 

Response: For areas remaining in nonattainment for the 1997 ozone NAAQS and designated 

nonattainment for the 2008 ozone NAAQS, the EPA does not believe that revocation of the 

NAAQS should halt or delay the planned implementation of control measures. These measures, 

while adopted pursuant to the 1997 ozone NAAQS, will also assist the areas in attaining the 
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2008 ozone NAAQS. All requirements remain in effect until they are addressed – either through

a redesignation to attainment for the most current ozone NAAQS, or through an approved 

redesignation substitute showing. Under the principles of Section 172(e), backsliding does not 

occur where there are controls that are no less stringent than those “applicable to” an area before 

a standard was revoked. 

2. New Source Review

Comment: Areas designated attainment for the 2008 NAAQS

Commenter (0151) stated that the proposed NSR requirement goes beyond the Court’s decision 

in South Coast which does not require NSR requirements associated with a previous standard be 

retained in areas (other than in ozone transport areas) designated attainment for the current 

standard since such areas by law must then implement PSD (South Coast, citing Greenbaum v. 

EPA, 370 F.3d at 536). Commenter (0151) also stated that the regulations in Appendix S and 

Parts 51 and 52 do not require amendment to reflect this interpretation.

Commenter (0180) disagreed with the EPA’s proposal to allow areas that are designated 

attainment for the 2008 ozone NAAQS but nonattainment for the 1997 NAAQS to request that 

any nonattainment NSR requirements be removed from the SIP. Commenter (0180) stated that 

this proposal is in direct conflict with South Coast and the subsequent decision in NRDC. 

Commenter (0180) stated that areas may not backslide on applicable control requirements such 

as NSR as long as they continue to violate the prior ozone standards and cited NRDC, 643 F.3d 

at 322. Commenter (0180) stated that the EPA’s reliance on Greenbaum is misplaced because 

the waiver the EPA is inventing here is not to allow an attainment area to implement PSD in lieu 

of NSR, but to allow a nonattainment area, that has not attained the 1997 standard, to avoid NSR. 

Commenter (0180) stated that the problem is that there are areas designated attainment for the 

2008 ozone NAAQS that are currently violating the 1997 ozone NAAQS. 

Response: For areas designated attainment for the 2008 ozone NAAQS but nonattainment for 

the 1997 ozone NAAQS, the EPA proposed that after the 1997 ozone NAAQS is revoked, these 

areas would not be required to retain in their SIPs nonattainment NSR programs for ozone. 

Instead, such areas would be required to implement PSD requirements for ozone. The EPA’s 

determination that after revocation of the 1997 ozone NAAQS nonattainment NSR requirements 

do not apply to areas designated attainment for the 2008 ozone NAAQS is consistent with the 

Greenbaum v. EPA decision.33 The EPA believes that not only is this action in line with the 

Greenbaum decision, but it also makes sense due to the fact that the 1997 and the 2008 ozone 

NAAQS are of the same form. An area that is attainment for the 2008 ozone NAAQS is attaining 

the most current and health protective ozone standard. The EPA believes that Congress did not 

 

33 Greenbaum v. EPA, 370 F.3d at 536. “It would make little sense for [nonattainment NSR] to 

be included in the post-attainment SIP, as the Clean Air Act . . . explicitly states that attainment 

area SIPs must include a PSD program.”
219

intend nonattainment NSR to apply as a minimum requirement in areas designated attainment, 

for a newer, more stringent standard of the same form. 

EPA believes that this approach is consistent with the conclusion in South Coast that the EPA 

can revoke a standard, so long as it establishes anti-backsliding measures for areas that failed to 

attain the standard before revocation that impose controls that are no less stringent than the 

controls that applied before revocation. Nothing in NRDC v. EPA forecloses this approach. The 

EPA disagrees with any suggestion that an area would remain subject to NSR or section 185 fees 

for failure to attain a revoked standard after the area has been formally designated as an 

attainment area for ozone,. Areas cannot be redesignated to attainment for ozone unless they 

have attained all current standards and met all anti-backsliding requirements applicable for prior 

revoked standards. Moreover, nonattainment NSR is not a requirement in attainment areas and 

section 185 fees by the terms of section 185 do not apply to an area that has been designated “an 

attainment area for ozone.”

Such areas designated attainment for the 2008 ozone NAAQS but that have failed to attain for 

the 1997 ozone NAAQS will be allowed to implement PSD for the 2008 ozone NAAQS once the 

revocation of the 1997 ozone NAAQS takes effect. The references to nonattainment 

designations for the 1997 ozone NAAQS in 40 CFR part 81 will remain for historical purposes 

and discrete purposes relevant to carrying out the anti-backsliding requirements.

Comment: Exemptions in 40 CFR 51.166(i)(2) and 52.21(i)(2) after revocation of a NAAQS

Commenters (0163, 0179) supported an amendment to 40 CFR 51.166(i)(2) and 52.21 (i)(2) for 

clarification as to the applicability of stationary source controls for a revoked NAAQS. 

Commenter (0163) added that the EPA should therefore reassess the ozone designations made 

last year by using 2010 to 2012 ozone data and, where this current design value exceeds the 2008 

ozone NAAQS, redesignate these areas to nonattainment.

Response: Based on this feedback, the EPA developed amendments to both 40 CFR 51.166(i)(2) 

and 52.21(i)(2). These amendments make it clear that a nonattainment designation for a revoked 

NAAQS, once the revocation becomes effective in an area, would not trigger the PSD exemption 

in those provisions and would not prevent application of PSD requirements for that pollutant. 

Comments focused on the designation process are beyond the scope of this rulemaking.

3. Section 185 fees

Comment: EPA should clarify section 185 fee requirements and the redesignation

provisions

Commenter (0132) stated that, while they support revocation of the 1997 eight-hour ozone 

standard, the EPA should continue to formally redesignate areas to attainment of the revoked 

standard if the state submits an approvable redesignation request and maintenance plan for that 

standard, since without such a redesignation, it is possible that nonattainment consequences, 

including the assessment of §185 fees, may continue to be imposed on an area that is no longer 
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monitoring nonattainment for the one-hour ozone standard and/or the 1997 eight-hour ozone 

standard. 

Commenter (0142) stated, in the final rule the EPA should provide clarity for Section 185 fees 

associated with revoked standards, particularly where the EPA has determined that those areas 

have met the standards. The commenter recommended that the EPA provide explicit guidance to 

states regarding how to terminate potential Section 185 fees associated with the revoked 

standards. Several regions have areas that were designated Severe or Extreme non-attainment 

under one of the revoked NAAQS. However, particularly with regard to the long-revoked 1-hour 

standard, these areas have no way to formally terminate the potential obligation, even if air 

quality has met the standard for years. As a practical matter, sources in these areas have already 

spent millions of dollars for emission reduction technologies with the resultant air quality 

benefits while additionally being required to set aside potential Section 185 fees until the 

question is settled. This results in millions of dollars annually from environmental compliance 

budgets idled and not being used for initiatives that would actually contribute to furtherimproved air quality in these areas. Therefore, we request that the final ozone implementation 

rule provide an unambiguous pathway for states to clarify and, where appropriate, terminate 

Section 185 fee obligations associated with the revoked standards.

Commenter (0177) stated that the EPA should include provisions in the rule to permanently 

relieve states of CAA section 185 fee obligations once the EPA has issued a ruling that an area 

has attained the corresponding NAAQS.

Response: In the final rule, states with nonattainment areas classified as Severe or Extreme for a 

prior NAAQS at the time that NAAQS is revoked remain subject to the requirements of section 

185 with respect to that NAAQS. This approach is consistent with the July 2011 NRDC court 

decision on the EPA's previously-issued section 185 guidance, which was vacated for procedural 

reasons but provided that, based on the principles of 172(e) an area can meet its 185 fee 

obligation using equivalent measures that are not less stringent than those that a fee program 

would impose. The NRDC decision held that neither the statute nor caselaw obviously precludes 

alternative programs and the EPA is currently defending its approval of two alternative 

programs. Medical Advocates for Healthy Air v. EPA. 9

th Cir. No. 12-73386; NRDC v. EPA, 9th

Cir. No. 13-70544. The final rule provides two methods to terminate section 185 anti-backsliding 

requirements for a revoked NAAQS: redesignating to attainment for the most current ozone 

NAAQS, and providing a redesignation substitute for the revoked NAAQS triggering the section 

185 requirement.

Comment: Use of section 185 fee revenues to improve air quality

Commenter (0142) recommended that these funds be directed toward projects that will improve 

air quality and promote attainment with the ozone NAAQS and ultimately result in the 

termination of the fee. The commenter believed that consideration of the use of collected Section 

185 fees is critical, particularly as the EPA intends for this implementation rule to guide 

implementation of the 2008 standard as well as any future revisions to the ozone NAAQS. The 

Section 185 fee is $5,000 per ton in 1990 dollars, adjusted for inflation; the fee is now nearly 

$9,000. Thus, implementation of the Section 185 fee program-- in areas that remain out of 
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attainment with the standards, not just without a path to terminate the obligation -- has the 

potential to generate significant revenues. However, the CAA does not specify how states (or 

appropriate authorities) may spend or allocate the fees collected under a Section 185 fee 

program. Therefore, states have discretion in how they use the fees. We would recommend that 

these funds be directed toward projects that will improve air quality and promote attainment with 

the ozone NAAQS and ultimately result in the termination of the fee. 

The commenter suggested that sources using this option should be required to submit a plan for 

approval to the state outlining the project (or projects) that they plan to implement based on their 

applicable fee amount. A state plan, or the EPA's approval thereof, could outline a variety of 

approvable project categories. Commenter (0142) listed several examples of suitable projects 

(not repeated here) and stated that the Clean Air Communities program in New York provides an 

example of how Section 185 fees might be deployed to more-effectively reduce precursor 

emissions.

The commenter also recommended allowing sources to invest in pollution control projects within 

the immediate nonattainment area, as well as adjoining upwind areas, in recognition of the fact 

that ozone pollution can be transported over long distances. The EPA's Office of Atmospheric 

Programs should have a multitude of studies available, including back trajectory analyses, which 

would allow the EPA and states to place reasonable geographic limitations on this option.

Response: The CAA does not specify how states may spend or allocate the fees collected under 

a section 185 fee program or an alternative equivalent program. Therefore, states have discretion 

on how to use the fees collected. The EPA believes that a beneficial approach would be to 

channel the fees into innovative programs as described by the commenter to provide incentives 

for additional ozone precursor emissions reductions from stationary or mobile sources, or for 

other purposes aimed at reducing ambient ozone concentrations in the affected area.

Comment: Support alternative section 185 fee programs

Commenter (0151) stated that it is both legal and economically essential to allow States to adopt 

under Section 172(e) alternatives to 185 fee programs as the agency has approved in several 

California jurisdictions. Commenter (0151) stated that applying in the future four penalty 

programs to a source that has the geographical misfortune to be located in an intractable ozone 

nonattainment area would be harmful to the economy and also to the public and would be 

unlikely to have any impact on an area’s attainment status given that the fee is not joined to any 

pollution control measure. Commenter (0151) stated that Congress could not have meant to 

impose iterative penalty fees for each ozone standard and, at the very least, this rulemaking 

should ensure that at most, only one ozone 185 penalty (or its equivalent) should apply to a 

jurisdiction at a time until it attains that standard or the most recent ozone standard.

Response: We agree with the commenter that CAA section 172(e) allows alternative programs 

to substitute for the CAA section 185 fee programs that are triggered for revoked standards. 

I. Application of Transition Requirements to Nonattainment and Attainment 
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Areas

1. Requirements for Areas Designated Attainment for the 2008 Ozone NAAQS and 

Maintenance for the 1997 Ozone NAAQS

Comment: Support the preferred approaches 

Commenters (0130, 0137, 0139, 0141,0145, 0146, 0151, 0153, 0155, 0157, 0158, 0163, 0166

and 0179) generally supported the EPA’s preferred approaches; i.e., that approved section 175A 

maintenance plans for the 1997 ozone NAAQS and SIP-approved PSD programs also satisfy 

their obligations for maintenance plans under CAA section 110(a)(1) for the 2008 ozone 

NAAQS. 

Commenters (0130, 0155, 0157 and 0158) stated the proposed options will both protect air 

quality and minimize needless paperwork at the state level and at the EPA regional level. 

Commenters (0139 and 0179) stated that, for the areas that have been redesignated as 

maintenance for the 1997 standard, the area remains subject to the nonattainment requirements 

already approved in their SIP and thus any revision would be subject to CAA sections 110(l) and 

193, which function as anti-backsliding provisions. 

Commenter (0163) stated that since the area is meeting a more stringent standard, public health 

protection is maintained by the existing plan and a second maintenance plan for a revoked 

standard would be unnecessary.

Commenters (0155 and 0157) supported these approaches as long as the EPA requires that an 

area still be attaining the 2008 ozone NAAQS in order to be eligible to eliminate the second 10-

year maintenance plan. 

Commenters (0158, 0159 and 0169) supported the EPA’s preferred option to not require a 

further maintenance plan. Commenter (0158) stated that these areas have already developed 

nonattainment SIPs for the previous 1997 standard that in combination with other federal 

measures have produced sufficient emission reductions to achieve the current, more stringent 75-

ppb standard and should not be burdened with developing a maintenance plan. 

Commenter (0159) stated that the approval of the redesignation and of the Section 175A 

maintenance plan for the 1997 ozone NAAQS required a determination on the EPA's part that 

the anti-backsliding requirements of these areas for the 1-hour standard, as well as those 

requirements applicable for the 1997 ozone standard, had been met. As such, commenter (0159) 

stated that the EPA's approval of both the redesignation request and the maintenance plan for the 

1997 ozone standard signifies not only that all applicable requirements for the 1997 ozone 

standard have been met, but also that all applicable anti-backsliding measures for the 1-hour 

ozone standard have been adopted and approved into the SIP. 

Commenter (0169) stated that South Carolina's experience with Cherokee County, SC, which 
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was redesignated to attainment in December 1992, and was required to submit an initial 175A 

maintenance plan, a subsequent 175A maintenance plan, and a 110(a)(1) maintenance plan, 

shows that these requirements were and continue to be unduly burdensome on the State and have 

resulted in few if any emissions reductions. 

Commenter (0145) agreed with the EPA’s rationale that, given the succession of NAAQS of 

increasing stringency, the burden of developing an approvable CAA §110(a)(1) maintenance 

plan for the 2008 ozone NAAQS would outweigh any compensating benefit for an area that is 

already attaining that NAAQS and that is subject to prior nonattainment requirements which are 

already incorporated into the SIP. 

Response: We believe that using the area’s approved section 175A maintenance plan for the 

revoked 1997 ozone NAAQS to satisfy both its maintenance obligations under section 110(a)(1) 

for the 2008 ozone NAAQS and its obligation to submit a second approvable maintenance plan 

under section 175A for the revoked 1997 ozone NAAQS is a sound approach. We believe that 

this approach keeps in place the control measures used to bring the area into attainment for both 

the 1997 and the more stringent 2008 ozone NAAQS, and also serves to reduce the paperwork 

burden on states.

Comment: Clarification needed

Commenter (0169) suggested the EPA clarify what is meant by "modify a maintenance plan." at 

51.1105(d)(l) to provide flexibility and efficiency. Commenter (0169) stated the rule should also 

reference the 1-hour ozone standard's original nonattainment designation and subsequent 

redesignation. Commenter (0169) stated that areas which have submitted clean data 

determination and/or redesignation requests should also be mentioned in this exemption. 

Response: The EPA made a modification to the regulatory text to provide the requested 

clarification. The text in question, as modified, provides that “an area with an approved 1997 

ozone AAQS maintenance plan under CAA section 175A is not required to submit a second 10-

year maintenance plan for the 1997 ozone NAAQS 8 years after approval of the initial 1997 

ozone NAAQS maintainance plan.”

Areas that were not redesignated to attainment for the 1997 ozone NAAQS prior to the date of 

revocation are not covered by this section. Areas that are in attainment for the 2008 ozone 

NAAQS but remain in nonattainment for the 1997 ozone NAAQS are addressed in the following 

section. Areas that have a clean data determination (CDD) for the 1997 ozone NAAQS in place 

have certain planning requirements suspended, but a CDD alone does not qualify an area to the 

flexibilities discussed in this section.

Comment: Do not support the proposed approaches

Commenter (0168) stated that not requiring maintenance plans in all cases is ignoring the 

maintenance provisions of the CAA that were intended to continue indefinitely. Commenter 

(0180) stated this proposal violates the plain language of section 110(a)(1), which requires a 

maintenance plan specifically for the new 2008 standard. Commenter (0168) also disagreed with 
224

the proposal because it is essentially using current air quality to determine the applicability of 

CAA section 110 maintenance plan requirements, which is contrary to the CAA. 

Commenter (0180) stated that demonstrating long-term compliance with the 1997 standard, 

which is the function of the 175A maintenance plans, does not demonstrate continued 

compliance with the more protective 2008 standard. Commenter (0180) stated that sections 

110(l) and 193 are not adequate to keep emissions from increasing and that, even without rule 

changes, emissions can increase with changes in activity. Commenter (0180) stated the EPA’s 

rationale that national rules and PM2.5 control measures will support maintenance of the 2008 

standard is based on over-broad generalizations without any supporting analysis. There is 

nothing in these claims that can support wiping away statutory requirements in all 2008 

attainment areas. 

Commenter (0180) stated that the EPA’s claim that its review of the ozone standards may come 

before section 110(a)(1) plans are due is factually incorrect and opens the door for the EPA to 

perpetually excuse compliance with section 110(a)(1). Commenter (0180) stated the CAA 

requires a formal SIP submittal to ensure that the NAAQS will be maintained and that such plans 

are enforceable; it is not enough to show that an area happened to meet the 2008 standard at the 

time of designations. 

Commenter (0180) stated that, if the EPA means that areas that are redesignated attainment for 

the 1997 ozone NAAQS and designated attainment for the 2008 ozone NAAQS, do not have to 

submit a “Good Neighbor” SIP as required by section 110(a)(2)(D)(i)(I) for the 2008 ozone 

NAAQS because they have a section 175A maintenance plan for the 1997 NAAQS, the EPA has 

rejected this approach. Commenter (0180) stated that the EPA rejected Kentucky’s 2008 ozone 

NAAQS section 110(a)(2)(D)(i)(I) submittal because the submittal relied on CAIR, which is 

designed to address the 1997 ozone NAAQS, and Kentucky did not submit any analysis or 

regulations addressing the 2008 ozone NAAQS. Commenter (0180) stated there is the added 

problem that a section 175A maintenance plan is not designed or required to prevent interference 

with maintenance or attainment in downwind states or visibility; therefore, the EPA cannot 

waive the 2008 ozone section 110(a)(1) obligations for any area.

Response: The EPA disagrees with the commenters. The EPA is not ignoring the maintenance 

provision of section 110(a)(1), but rather evaluating what is sufficient to address that provision 

under the circumstances of transition to a new more stringent NAAQS for an area designated 

attainment for that more stringent NAAQS. With the control measures included in their SIPs and 

in approved section 175A maintenance plans, those areas have already achieved sufficient 

emissions reductions to bring the area into attainment for both the 1997 ozone NAAQS and the 

more stringent 2008 ozone NAAQS. These SIP control measures cannot be weakened without 

satisfying section 110(l) and in some cases also section 193, which effectively serve as antibacksliding provisions. The EPA is not relieving areas designated attainment of the requirement 

under section 110(a)(1) to maintain the more stringent 2008 ozone NAAQS, but rather, the EPA 

believes the current SIP measures together with the approved PSD plan for the 2008 ozone 

NAAQS suffice as a maintenance showing for these areas. These are areas that already have 

many controls in place, including approved section 175A maintenance plans ensuring that the 

areas can maintain the level of the prior revoked standard. 
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While these approved 175A maintenance plans were established for maintenance of the 1997 

ozone NAAQS, and accordingly help prevent backsliding for that revoked NAAQS, they also 

provide a foundation for maintenance of the 2008 ozone NAAQS, which, in combination with 

other active Clean Air Act requirements for the 2008 ozone NAAQS, contribute to maintenance 

of the new standard. The emissions reductions for one NAAQS build upon the emissions 

reductions from previous NAAQS. The EPA concludes that it is not necessary for the state to 

adopt additional measures beyond the prior 175A maintenance plans and the PSD plans for the 

2008 standard to provide for maintenance in these areas. The EPA will work with states as 

necessary under the provisions of the Clean Air Act to address any future air quality concerns 

and maintenance needs for these areas.

The EPA is not attempting in this rule to relax any infrastructure SIP requirements, including the 

“Good Neighbor” SIP required under CAA section 110(a)(2)(D)(i). Only the 110(a)(1) 

maintenance plan requirements are affected by this rule. The EPA issued its “Guidance on 

Infrastructure State Implementation Plan Elements Under the Clean Air Act Sections 110(a)(1) 

and 110(a)(2),” on September 13, 2013, on the required elements of the section 110 

infrastructure SIP submittal for the 2008 ozone NAAQS. This guidance is located at 

http://www.epa.gov/oar/urbanair/sipstatus/infrastructure.html.

Comment: Need to reconsider the EPA approaches

Commenters (0146 and 0163) urged the EPA to reconsider its assumptions about the relationship 

between the 1997 and 2008 ozone NAAQS and develop an anti-backsliding approach that 

properly characterizes ozone violations and nonattainment. The commenters pointed out where 

the EPA made the statement that "because the form of the 1997 and 2008 ozone NAAQS is the 

same, there is no possibility that an area attaining the 2008 ozone NAAQS could be violating the 

1997 ozone NAAQS, which is unlike the relationship that existed between the 1-hour ozone 

NAAQS and the 1997 ozone NAAQS." The commenters believed this "impossibility" has indeed 

occurred. The Louisville metropolitan area (a maintenance area under the 1997 ozone NAAQS) 

was designated attainment under the 2008 ozone NAAQS based on 2008-2010 data. With 2010-

2012 data and a design value 0.085 ppm, the area violates both the 2008 and 1997 ozone 

NAAQS. The commenters supposed that the EPA has indicated that it has no intention of 

redesignating areas based on more recent data so it appears that the Louisville area will need to 

invoke its contingency plan for the 1997 ozone NAAQS while the EPA considers the area 

attainment for the stricter 2008 NAAQS. To address this inconsistency, the commenters 

suggested that the EPA should redesignate areas under the 2008 NAAQS based on 2012 ozone 

data. This would allow the ozone problem to be properly characterized in its breadth and 

severity.

Commenter (0177) stated that the EPA’s proposed approach only makes sense from an air 

quality perspective if the designations of those recently violating areas are quickly updated under 

CAA section 107(d)(3). 

Response: We disagree that EPA must consider air quality data that was not available in 

sufficient time for initial designations and designate areas based on that new data for purposes of 
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determining appropriate anti-backsliding requirements prior to revoking the 1997 ozone 

NAAQS. Although not directly applicable where EPA strengthens the standard, EPA has used 

the anti-backsliding principles in section 172(e) as a guide for anti-backsliding for the 1997 

NAAQS. Section 172(e) does not contemplate that there is an ongoing obligation to impose more 

stringent controls than those that were in place at the time of revocation.

2. Areas Designated Attainment for the 2008 Ozone NAAQS and Nonattainment for 

the 1997 Ozone NAAQS

Comment: Support PSD SIP option

Commenter (0139) stated that, for areas designated attainment for the 2008 ozone NAAQS and 

nonattainment for the 1997 ozone NAAQS category in row 2 of Table 2, an option is given for 

area’s approved PSD SIP to satisfy the section 110(a)(1) maintenance provision. Commenter 

(0139) stated that they supported this option, as it would avoid an additional maintenance 

showing under 110(a)(1), and it is also appropriate for the category noted above and should be 

added as a third bullet item in row 1 of Table 2.

Commenter (0179) believes the alternative approach brings additional unnecessary resource 

burden to the states. Commenter (0166) stated that the second alternative lacks legal basis in the 

statute since maintenance plans are required for an area to be redesignated to attainment, but the 

EPA here is simply proposing to revoke the 1997 NAAQS. 

Response: The EPA finalized the approach that an approved PSD SIP for such an area satisfies

the obligation to submit an approvable maintenance plan for the 2008 ozone NAAQS under 

section 110(a)(1). The EPA believes that the burden of developing an approvable 110(a)(1) 

maintenance plan for the 2008 ozone NAAQS would outweigh any compensating benefit for an 

area that is already attaining that NAAQS and that is subject to prior nonattainment requirements 

which are already incorporated into the SIP and have been sufficient to bring the area into 

attainment of both the 1997 and 2008 standards.

Comment: Maintenance plan needed 

Commenter (0163) stated that an RFP SIP for the 2008 ozone NAAQS for an area classified

Moderate or higher would satisfy the maintenance requirement for the 1997 NAAQS as it would 

document required emissions reductions. Commenter (0163) stated that the EPA's proposed 

approach, however, does not demonstrate continued maintenance; so an area designated marginal 

nonattainment should prepare a maintenance plan to set conformity budgets and assure continued 

maintenance.

Commenter (0163) agreed with and preferred the "alternative" approach with the caveat that 

areas be assessed and designated according to current (2012) design values. The commenter 

believed that under the "preferred" approach, 1997 ozone NAAQS former nonattainment areas 

that did not prepare maintenance plans would not have any maintenance obligations, but former 

1997 ozone NAAQS nonattainment areas that prepared maintenance plans would be subject to 
227

the requirements in these plans. The alternative approach would remove this inequity and 

provide assurances for continued attainment.

Response: The EPA disagrees with the commenters. The control measures implemented by 

these areas and included in their SIPs have already produced sufficient emissions reductions to 

achieve air quality that not only attained the 1997 ozone NAAQS, but also resulted in an 

attainment designation for the more stringent 2008 ozone NAAQS. These control measures 

cannot be modified or removed without a demonstration satisfying section 110(l) and in some 

cases both sections 110(l) and 193. These demonstrations must address not only the 1997 ozone 

NAAQS but also the 2008 ozone NAAQS as well as any future NAAQS.

Comment: Do not support the proposal 

Commenter (0180) stated that waiving the requirements of section 175A(b) without support is 

arbitrary and undermines the protections of the Act. Commenter (0180) stated that, given the 

ability of nonattainment areas under the 2008 standard to claim that RACM/RACT requires no 

additional controls beyond those already in place, to extend attainment deadlines through “bump 

ups,” to defer implementation of any new control measures, and to allow emissions to increase 

even without changes in applicable control measures (e.g., through increases in population or 

economic activity), there is no assurance that the planning requirements for the 2008 standard 

will prevent ambient concentrations from increasing. 

Commenter (0180) stated the EPA is not clear whether it is also proposing to waive the revision 

requirements of section 175A(b) for 1997 ozone standard maintenance areas if the area is 

attaining the 2008 standard. Commenter (0180) stated such a proposal would be even more 

arbitrary since the EPA is proposing to rely on the maintenance demonstrations for the 1997 

standard to substitute for maintenance demonstrations under section 110(a)(1) for the 2008 

standard. Commenter (0180) stated that waiving the revision requirement under section 175A(b) 

would mean that there is no continuing obligation to demonstrate maintenance of either the 1997 

or the 2008 standard. Commenter (0180) stated that attainment of the 1997 standard is no proof 

that future levels will remain adequately controlled and pointed to the Washington DC-MD-VA 

nonattainment area which had achieved the 1997 ozone standards, but where ambient 

concentrations degraded over time between 2007 and 2012 and design values now exceed the 

1997 standard. Commenter (0180) stated that, since some areas may experience ozone increases 

over time, a second round of maintenance planning under section 175A(b) would ensure areas 

will not backslide into violation of the 1997 standards; nothing in the 2008 planning 

requirements can provide that assurance. 

Response: We believe that an approved PSD SIP, in conjunction with the other already-existing 

statutory and regulatory provisions that govern implementation of ozone standards, and the 

historical safeguards in place for the area adopted for prior NAAQS, are generally sufficient to 

prevent backsliding, and to satisfy the requirement for maintenance under section 110(a)(1). The 

control measures implemented by these areas and included in their SIPs have already produced 

sufficient emissions reductions to achieve air quality that attained the 1997 ozone NAAQS, and 

resulted in an attainment designation for the more stringent 2008 ozone NAAQS. These control 

measures cannot be modified or removed without a 110(l) showing and in some cases both a 
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110(l) and a 193 showing. Areas designated attainment for the 2008 standard remain subject to 

the attainment and maintenance requirements of that standard. These include continued 

implementation of the control measures that brought the area into attainment. For these areas, 

and for any area designated attainment for the 2008 NAAQS, the CAA’s general NAAQS air 

quality management framework and associated regulatory provisions continue to apply, and 

serve as the foundation for handling any potential future issues with maintaining the 2008 

NAAQS.

3. Areas Designated Nonattainment for the 2008 Ozone NAAQS and Maintenance 

for the 1997 Ozone NAAQS

Comment: Modify regulatory text

Commenter (0153) supported the EPA's proposed approach but stated that the proposed 

regulatory language at §51.1105(a)(4) states that after the 1997 standard is revoked the 

maintenance plan may be modified consistent with sections 110(1) and 193. However, 

commenter (0153) asserted the proposed regulatory language at §51.1105(a)(2) does not contain 

similar language to allow modification of the maintenance plan consistent with 110(1) and 193, 

and believed it should be added.

Response: The EPA agrees that the regulatory text regarding areas designated maintenance for 

the 1997 ozone NAAQS should be amended to include language consistent with the proposed 

and final approach. The regulatory text has been adjusted to reflect that maintenance plans can be 

modified pursuant to CAA sections 110(l) and 193.

Comment: A second maintenance plan is needed

Commenter (0163) stated that there needs to be a showing that emissions will not increase in the 

area and that maintenance is assured. The commenter suggested that this can be accomplished by 

preparing either a maintenance plan or an RFP SIP. In the case of areas in the OTR, 

nonattainment NSR is required as well as a number of other mandated measures. However, 

without a maintenance plan, mobile source emissions do not have commensurate checks on 

emissions growth. OTR areas should be given the option of demonstrating that projected mobile 

source emissions do not exceed the base year for a 10-year period. The commenter stated that an 

area designated nonattainment for the 2008 ozone NAAQS should prepare a second maintenance 

plan to assure maintenance and set conformity budgets. 

Another commenter opposed the proposal because the CAA clearly requires two 10-year 

maintenance plans. The fact that the area is designated nonattainment under the 2008 ozone 

NAAQS is no guarantee that there will be no increase in ozone violations. The commenter 

suggested that the EPA review the record for areas violating a NAAQS for which it had been 

redesignated to attainment with an approved maintenance plan. Waiving the requirements of a 

second 10-year maintenance plan as described in CAA section 175A(b) without support is 

arbitrary and undermines the protections of the Act.
229

Response: The EPA recognizes that the approved 175A maintenance plan for the 1997 ozone 

NAAQS can only be modified via a section 110(l) and, where appropriate, a section 193 

showing. These analyses would have to demonstrate that any revisions to the maintenance plan 

would not interfere with the ability to demonstrate timely attainment for the new standard. The 

final rule has not established a requirement for the second 10-year plan for maintenance of a 

revoked, less stringent standard that the areas previously attained. This allows states to focus 

planning and control efforts on attaining and maintaining the more stringent and currently 

applicable 2008 ozone NAAQS in these areas, rather than continued focus on the already 

attained 1997 ozone NAAQS. The areas will remain subject to the MVEBs established in the 

approved 175A maintenance plan until such time that MVEBs for the more stringent 2008 ozone 

NAAQS are submitted and are found adequate or are approved. These MVEBs must be used for 

transportation conformity determinations under the 2008 ozone NAAQS pursuant to the 

conformity regulations.

4. 2008 Nonattainment Areas Also Designated Nonattainment for a Prior Revoked Ozone 

NAAQS 

Comment: Clarification

Commenter (0132) requested clarification of the interpretation of Table 2: 2008 Ozone NAAQS 

Transition Obligations and Section (IV)(I)(4)(a)(ii). The commenter supposed that the EPA 

stated that it is proposing that "areas designated nonattainment for the 2008 ozone NAAQS and 

nonattainment for the 1997 ozone NAAQS will be obligated to implement the applicable 

requirements set forth in 51.1100(o) for the 1997 ozone NAAQS and ... must also continue 

addressing those applicable 1-hour ozone NAAQS requirements for that area." It continues to 

state that the area must apply nonattainment NSR in "accordance with their highest 

nonattainment classification under any ozone standard for which they are (or were at the time of 

revocation) designated nonattainment, as well as any section 185 requirements for areas 

classified Severe or Extreme at the time of revocation for a prior standard." This statement 

implies that an area that is in Severe (or Extreme) nonattainment status for both the 1-hour and a 

later ozone NAAQS standard would be subject to §185 fees for both standards. It is requested 

that the EPA clarify what requirements would satisfy a §185 fee for both standards. Would 

assessment of two separate fees with two different baseline amounts and years be required or 

would the §185 fee requirement be satisfied for both unmet standards if the higher of the two 

fees were assessed on major sources? It is noted that the higher of the two classifications is used 

for NSR purposes and assessing only the higher of the two fees could be consistent with NSR. 

Additionally, payment of a higher fee would fulfill the obligation of the smaller fee. 

Response: Section 185 provides that states establish fee programs for Extreme and Severe 

ozone areas to be implemented if the area fails to attain by the attainment date. The South Coast

decision determined that a section 185 fee program is a control that is needed to meet antibacksliding obligations. The EPA has concluded that, under the principles of section 172(e), a 

district can meet its section 185 fee anti-backsliding obligation by developing equivalent 

alternative measures to a section 185 fee program that are not less stringent than a fee program 

would be and has approved two such programs. The Ninth Circuit is currently considering 
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challenges to EPA’s approval of those programs. The commenter raises a hypothetical issue 

regarding implementation of the section 185 fee program that is beyond the scope of both the 

proposed and final rules. The EPA will consider the issues raised by the commenter if and when 

they arise in the context of a specific SIP submittal containing either a 185 fee program or an 

equivalent alternative program.

5. Table 2 requirements--clarifications

Comment: Clarification regarding 110(a)(1) plan

Commenter (0139) stated there may be cases for areas initially designated attainment for the 

1997 8-hr NAAQS in which a section 110(a)(1) maintenance plan was prepared, and not a 

Section 175 maintenance plan; therefore, for the Attainment (2008); Attainment /Maintenance 

(1997) category in row 1 of table 2 on page 34218, the following clarifying text should be added 

to address cases in which a 110(a)(1) plan was prepared:

“Section 175 A maintenance plan or section 110(a)(1) maintenance plan for the 1997 8-hr 

NAAQS satisfies maintenance requirement under section 110(a)(1)” 

Response: The requested modification was not made because it is unnecessary. In the 

circumstance the commenter describes, an area has been designated attainment and prepared a 

110(a)(1) plan for the 1997 ozone NAAQS and not a 175 maintenance plan the area faces no 

anti-backsliding requirements for the 1997 ozone NAAQS under this final rule.

J. Satisfaction of Anti-Backsliding Requirements for an Area

1. Formal redesignation satisfies anti-backsliding requirements

Commenters (0132, 0159, 0166, 0173 and 0179) generally supported the EPA's proposal that 

formal redesignation satisfies anti-backsliding requirements for revoked standards. 

Commenters (0132 and 0173) agreed that formal redesignation to attainment for the 2008 eighthour ozone NAAQS and approval of a maintenance plan demonstrates that an area has satisfied 

its obligations to adopt anti-backsliding requirements, including section 185 penalty fees. 

Commenter (0179) supported a formal redesignation approach and stated this would lift the 

nonattainment NSR requirements. 

Commenters (0132 and 0173) requested that the EPA preserve the statutory mechanism to 

redesignate areas to attainment for the 1997 NAAQS. Commenter (0132) stated that without 

such a redesignation, it is possible that nonattainment consequences, including the assessment of 

§185 fees, may continue to be imposed on an area that is no longer monitoring nonattainment for 

the one-hour ozone standard and/or the 1997 eight-hour ozone standard. Commenter (0132) 

stated that this is a particularly egregious type of punishment for areas that have not yet missed 

the applicable attainment date for a particular standard. Commenter (0173) stated that because 

the EPA's more streamlined options to eliminate anti-backsliding obligations for the 1997 
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NAAQS have not yet been tested in the courts, retaining the statutory redesignation mechanism 

for the revoked NAAQS will ensure that a procedure exists to allow 1997 NAAQS 

nonattainment areas to remove anti-backsliding obligations where circumstances warrant. 

Commenter (0181) opposed the other demonstrations required for formal redesignation 

(demonstration that air quality improvements were due to permanent and enforceable measures, 

and that the area will continue to maintain the standard over the next 10 years) and stated they 

are neither necessary nor appropriate. Commenter (0181) stated that the criterion for 

applicability of anti-backsliding requirements is nonattainment, not attainment designation. 

Commenter (0181) stated Congress intended this distinction, as demonstrated by its use of the 

phrase "designated nonattainment"; that is, Congress was aware of how to make a requirement 

effective based on an attainment designation, as distinguished from attainment. Commenter 

(0181) stated the EPA should allow an area to remove anti-backsliding requirements related to 

the one-hour ozone standard and 1997 eight-hour ozone standard upon attaining those standards 

(i.e., a "clean data determination") - particularly for areas - such as Pechanga's Tribal Lands -

where the original nonattainment designation was influenced by overwhelming transport from 

upwind areas. Commenter (0181) suggested that a State would need (1) to demonstrate that the 

NAAQS had been attained, and (2) to submit a revision to their SIP, proposing to remove the 

affected anti-backsliding requirements. Commenter (0181) stated this SIP revision would be 

subject to the provisions of 110(1) which prohibit approval of revisions that would interfere with 

attainment or reasonable further progress.

Response: Approval of a redesignation to attainment for the 2008 ozone NAAQS signifies that 

the state has satisfied its obligations to adopt anti-backsliding requirements for the current and 

revoked standards for that area. This same approach was used in the Phase 1 Rule in requiring 

redesignations for the 1997 ozone NAAQS to address anti-backsliding requirements for the 

revoked 1-hour standard. Approval of the section 175A maintenance plan for the 2008 ozone 

NAAQS assures that the area’s SIP includes the provisions necessary for maintenance of the 

2008 ozone NAAQS, which is the most stringent of the NAAQS. Therefore, upon redesignation 

to attainment and approval of its plan for maintenance of the 2008 ozone NAAQS, an area will 

have satisfied its obligations to adopt anti-backsliding requirements. All of the anti-backsliding 

measures that have been approved into the SIP must continue to be implemented unless or until 

the state can show that such implementation is not necessary for maintenance, consistent with 

section 110(l) and section 193 if applicable. 

The EPA does not agree that it has authority to take action to reclassify or redesignate areas to 

attainment for a former standard that has been revoked, such as the 1997 ozone NAAQS after 

that NAAQS has been revoked. Revocation of the standard removes the designations for the 

revoked standard, as well as the classifications, except to the extent necessary to implement 

applicable anti-backsliding requirements. The EPA believes the two mechanisms provided in the 

final rule for removing obligations arising from a revoked standard accomplish the goals of 42 

U.S.C 7407(d)(3) [CAA section 107(d)(3)] in a manner consistent with anti-backsliding 

principles and appropriate for the circumstance where a more stringent NAAQS with the same 

form and averaging time exists and is being actively implemented. Thus, we agree with the 

commenters that there should be a mechanism for removing certain obligations, such as section 
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185 fee programs based on failure to attain a former standard that has since been revoked after 

the state has attained that revoked NAAQS that can serve the same function as a formal 

redesignation to attainment. This is precisely the reason we developed the redesignation 

substitute. While the redesignation substitute has not been judicially reviewed, we believe that 

our approach is legally defensible.

The EPA does not believe that a clean data determination is sufficient to suspend antibacksliding requirements. We believe that the redesignation and redesignation substitute 

mechanisms represent the minimum set of requirements sufficient to demonstrate satisfaction of 

anti-backsliding requirements under the EPA’s application of the principles of section 172(e). 

These mechanisms provide a way for states to demonstrate that they have attained these 

standards, and have essentially met all the requirements for redesignations, and thus should no 

longer need to fulfill any additional anti-backsliding requirements beyond those already 

approved in their SIPs. A clean data determination only suspends planning requirements 

associated with the NAAQS for which the determination was granted.

CAA section 172(e), which addresses relaxations of a NAAQS, requires protections for areas 

that have not attained a NAAQS prior to a relaxation, by requiring controls that are “not less 

stringent” than the controls applicable in nonattainment areas prior to any such relaxation. The 

EPA applied these principles in developing previous guidance on satisfying the anti-backsliding 

approach for CAA section 185 requirements. As stated in previous EPA guidance, we interpret 

the principles of 172(e) as authorizing, but not requiring, the Administrator to approve on a caseby-case basis “not less stringent” alternatives to the applicable section 185 fee program 

requirements associated with a revoked ozone NAAQS.34 The NRDC challenged this guidance 

in 2010. Although the court vacated the 2010 guidance memorandum on procedural grounds, it 

did not prohibit alternative programs, stating that “neither the statute nor our case law obviously 

precludes that alternative.” See NRDC v. EPA, 643 F.3d 332 (D.C. Cir. July 2011). We believe 

the application of section 172(e) principles to applicable section 185 anti-backsliding 

requirements is an appropriate and reasonable use of the Administrator’s discretion to approve 

“not less stringent” controls. However, we did not propose and do not intend at this time to 

promulgate regulatory language to apply principles of section 172(e) to other anti-backsliding 

requirements.

Comment: Redesignation does not satisfy anti-backsliding requirements

Commenter (0180) stated redesignation (or initial designation) to attainment for the 2008 

standard cannot be used to turn off obligations triggered under the 1-hour or 1997 standards. 

Commenter (0180) stated that these obligations can only be turned off by meeting those 

standards. Commenter (0180) cited Chevron step 1 in NRDC, 643 F.3d at 322 (rejecting EPA 

 

34 Memo from Stephen D. Page to Regional Air Division Directors, Jan. 5, 2010, “Guidance on 

Developing Fee Programs Required by Clean Air Act Section 185 for the 1-Hour Ozone 

NAAQS.”
233

policy that would have allowed an area to use attainment of the 1997 8-hour ozone standard to 

terminate 185 fees triggered by noncompliance with the 1-hour ozone standard). Commenter 

(0180) also stated the court explained “the Act creates a one-way ratchet, ‘plac[ing] states onto a 

one-way street whose only outlet is attainment’ of the NAAQS – even NAAQS EPA has 

subsequently replaced.” Id. (quoting SCAQMD, 472 F.3d at 900). 

Commenter (0180) stated this is particularly important because the data EPA used to make 

designations for the 2008 ozone NAAQS were low due to the Great Recession and/or cool 

weather and, as such, do not indicate that serious, severe or extreme 1997 ozone NAAQS 

nonattainment areas will attain by their attainment date. Commenter (0180) stated that, if the 

EPA believes that attainment of the 2008 NAAQS will necessarily mean attainment of the earlier 

standards, then there is no reason for this option because areas meeting the 2008 standard should 

also be able to demonstrate attainment with the prior standards and go through the statutorily 

provided redesignation process. 

Response: The EPA disagrees with the commenter. When the EPA approves a redesignation 

request for the current 2008 ozone NAAQS, we assess whether the area is in attainment for the 

current and previous NAAQS. The maintenance plan submitted by the state demonstrates that the 

area being considered for redesignation will continue for the next 10 years to attain the standard 

that is requisite to protect public health, and that attainment is due to permanent and enforceable 

emissions reductions. A redesignation to attainment signifies that the area has met the 

requirements of the 2008, as well as any revoked, NAAQS. CAA section 185 specifically 

identifies redesignation “as an attainment area for ozone” as a basis for terminating fee 

requirements. Also, redesignation to attainment historically has terminated nonattainment NSR 

requirements, which are not required to be kept in the SIP as contingency measures. See

Greenbaum v. EPA (370 F.3d at 536). Moreover, redesignation for the current standard was the 

unchallenged basis for demonstrating satisfaction of anti-backsliding requirements in the EPA’s 

previous Phase 1 anti-backsliding regime (69 FR 23951). We believe the application of the same 

principle when transitioning from the 1997 to the 2008 ozone NAAQS is an even better fit: it is 

impossible to attain the 2008 ozone NAAQS without first achieving air quality that would attain 

the 1997 ozone NAAQS due to the identical form of the two standards.

2. Redesignation Substitute satisfies anti-backsliding requirements

Comment: Support redesignation substitute

Commenters (0130, 0136, 0139, 0145, 0151, 0153, 0158, 0159, 0160, 0163, 0166, 0177, 0178

and 0179) generally supported the EPA's proposal to provide a redesignation substitute to satisfy 

anti-backsliding requirements for revoked standards.

Commenter (0130) stated that inventories and modeling needed for the redesignation substitute 

should rely heavily on existing data, since new inventories and analyses would generate a great 

deal of work for a standard that may have been met for many years. Commenter (0130) stated 

that the EPA should also allow states to supply inventories in terms of tons/year rather than 

ozone season tons/day.
234

Commenters (0139 and 0150) supported the concept of a “redesignation substitute” in the sense 

that there needs to be a clear path for the states to follow in order to eliminate the antibacksliding requirements attendant on failure to attain a revoked standard. 

Commenter (0130) stated that the EPA should clarify that mobile vehicle emissions budgets are 

not required for a redesignation substitute since such budgets by necessity must be SIP 

submissions and must at a minimum be deemed adequate by the EPA. 

Commenter (0130) stated that, since this is not a maintenance plan under Section 175A, the EPA 

should consider allowing states flexibility in creating this document. 

Commenter (0132) recommended that the “substitute redesignation procedure be streamlined so 

that two steps, notification and the attainment/maintenance demonstration that would currently 

be required are rolled into one submission. Commenter (0132) stated this process could result in 

significant delays while the state waits for EPA action on the initial redesignation showing; 

rather, as is done with formal redesignation requests that are submitted concurrently with 

maintenance plans, a redesignation substitute could be submitted concurrently with the necessary 

SIP revisions to remove nonattainment SIP requirements. Commenter (0162) supported a 

streamlined process to minimize the burdens on state and industry as they attempt to comply 

with implementation requirements associated with multiple iterations of the ozone NAAQS—

1997, 2008, and projected 2014/15 standards. 

Commenter (0151) stated the proposed rule should be modified so that when the State notifies 

the EPA that it will be submitting its Clean Data demonstration and maintenance plan, all SIPplanning activities under the 1997 ozone standard are suspended unless and until the EPA 

determines through the contemplated notice and comment “substitution procedure” that the State 

has failed to show that it is able to attain and/or maintain the former ozone standard. Commenter 

(0151) stated that it seems pointless to insist that 1997 ozone planning continue. 

Commenter (0153) supported this concept, but believed the EPA should specify that a 

maintenance plan submitted prior to revocation of the 1997 standard satisfies a states need to 

provide a showing that addresses the substance of the redesignation criteria, provided that the 

maintenance plan that was submitted meets the requirement of section 107(d)(3)(E).

Commenter (0158) stated the EPA should move expeditiously to address and finalize any 

outstanding state redesignation or clean data requests with respect to the 1997 8-hour ozone 

standard so that formal, official redesignations or clean data determinations can be finalized prior 

to the revocation of the 1997 8-hour standard.

Commenters (0159 and 0177) stated that the EPA's alternative approach prevents such areas 

from being treated more harshly than those areas that achieved the 1997 ozone standard prior to 

its revocation. 
235

Commenter (0163) supported this approach, stating it is reasonable in that it does not include all 

of the provisions required for redesignation, but eliminates the discrepancies created under the 

earlier approach that only required a showing of attainment. 

Commenter (0179) supported both proposed options for addressing nonattainment NSR 

requirements for any prior ozone standard for which an area remains designated nonattainment.

Response: The EPA recognizes that a clean data determination alone is less burdensome for 

states than a section 107(d)(3) redesignation or a redesignation substitute. But a clean data 

determination only suspends planning requirements associated with the NAAQS for which the 

determination was granted. We believe that the formal redesignation and redesignation substitute 

mechanisms represent the minimum set of requirements sufficient to demonstrate satisfaction of 

anti-backsliding requirements under the EPA’s application of the principles of section 172(e). 

These mechanisms provide a way for states to demonstrate that they have attained these 

standards, they have met all the requirements for redesignations, and thus no longer need any 

anti-backsliding requirements beyond those already approved in their SIPs. The EPA believes 

the redesignation and redesignation substitute mechanisms, and their associated requirements 

reasonably address backsliding requirements in a manner that can be legally supported.

The EPA intends to act as quickly as possible on all redesignation requests received from states 

prior to revocation of the 1997 ozone NAAQS. While we believe that we cannot redesignate 

areas to attainment for a revoked NAAQS, we can issue clean data determinations and 

determinations of attainment to areas for that revoked NAAQS.

Comment: Oppose redesignation substitute

Commenter (0152) believed that, although the proposed “redesignation substitute” process 

would not be a formal SIP process, it would be subject to notice and comment, would be 

resource intensive, and would be unnecessary, especially given that the EPA does not even have 

the authority to redesignate an area to attainment for a revoked standard. Commenter (0152) 

stated the Phase 1 Rule process should continue; i.e., when an area attains under the revoked 1-

hour ozone standard, a state merely needs to show attainment and the EPA makes a 

determination of attainment.

Response: The EPA believes that the redesignations substitute mechanism represents the 

minimum set of requirements sufficient to demonstrate satisfaction of anti-backsliding 

requirements for a revoked NAAQS under the EPA’s application of the principles of section 

172(e). The only other route to demonstrate the satisfaction of anti-backsliding requirements is a 

redesignation to attainment for the most current ozone NAAQS. A clean data determination only 

suspends planning requirements for a specific NAAQS, and a determination of attainment only 

serves to note that the area attained by the assigned attainment date.

Comment: More extensive showing

Commenters (0139, 0150, 0166 and 0173) questioned why the EPA considers this more 

extensive showing necessary, since when the EPA revokes a standard, it does so because it 
236

believes it is no longer needed. Commenters (0166 and 0173) questioned whether it is necessary 

for the redesignation substitute to include a maintenance demonstration. Since the state must 

prepare a SIP for the area to bring it into compliance with the more-stringent 2008 standard, 

commenter (0166) stated it seems an unnecessary burden to require that the state also prepare a 

demonstration that air quality will not degrade such that the earlier standards are no longer met. 

Commenter (0173) stated that the EPA terminated anti-backsliding obligations in the Baton 

Rouge and Beaumont-Port Arthur areas without requiring such a maintenance demonstration for 

the 1-hour ozone NAAQS and noted that many areas seeking such a redesignation substitute will 

likely also be subject to rate-of-progress requirements or maintenance plans for other ozone 

NAAQS, that will in practice continue to assure emission reductions consistent with air quality 

maintenance. 

Response: We believe that the redesignation substitute mechanism represents the minimum set 

of requirements sufficient to demonstrate satisfaction of anti-backsliding requirements under the 

EPA’s application of the principles of section 172(e) and the requirements of 107(d)(3)(E). A 

redesignation substitute showing would include: attainment of the relevant revoked 1-hour 

and/or 1997 ozone NAAQS; a showing that attainment was due to permanent and enforceable 

emissions reductions; and a demonstration that the area can continue to maintain the standard 

over the next 10 years. 

The EPA recognizes that areas designated nonattainment for the 2008 ozone NAAQS that also 

remain nonattainment for a revoked NAAQS are likely designated at a lower classification for 

the 2008 ozone NAAQS as a result of the implementation of control measures for the 1997 

ozone NAAQS. Air quality improvements for the 2008 ozone NAAQS are built upon progress 

made for the previous ozone NAAQS. The EPA is not providing the redesignation substitute

mechanism for the purpose of allowing states to relax or avoid air quality control measures that 

are needed for attainment and maintenance of the 2008 ozone NAAQS.

We terminated the 1-hour ozone NAAQS anti-backsliding obligations for the Baton Rouge and 

Beaumont-Port Arthur areas, with the exception of the CAA 185 fee obligation for the Baton 

Rouge area, in conjunction with approval of a maintenance plan for the more stringent 1997 

ozone NAAQS (76 FR 74000, November 30, 2011 and 75 FR 64675,October 20, 2010, 

respectively).35 In addition to the option of demonstrating maintenance for a more stringent 

NAAQS, our final rule is reasonable in that it allows an alternative demonstration for the 

revoked NAAQS adequate to fulfill anti-backsliding requirements. 

 

35 For the Baton Rouge area we terminated the CAA section 185 fee obligation for the 1-hour 

ozone NAAQS in a separate rulemaking (July 7, 2011, 76 FR 39775). This rulemaking relied on 

our January 5, 2010 memorandum “Guidance on Developing Fee Programs Required by Clean 

Air Act Section 185 for the 1-hour Ozone NAAQS.” On July 1, 2011, the District of Columbia 

Circuit Court of Appeals vacated our 185 fee guidance. NRDC v. EPA, 643 F.3d 311 (D.C. Cir. 

2011).
237

Comment: NSR requirements

Commenter (0130) stated that a mechanism must be supplied to states to alleviate the overly 

burdensome requirements for NSR thresholds to which areas are subject, solely due to their 

status as a nonattainment area under the 1-hour ozone standard. Commenter (0130) stated that 

applying the NSR thresholds for 1-hour severe areas with no opportunity to alleviate those 

burdens does not provide a level playing field. For instance, any other area in the OTR 

designated marginal or moderate nonattainment for the 2008 ozone NAAQS should have NSR 

thresholds of 50 tpy VOC and 100 tpy of NOx as well as offset ratios of 1.15 to 1. The Northern 

Virginia area, under the EPA's current interpretation of anti-backsliding requirements, would 

have NSR thresholds of 25 tpy VOC and NOx as well as offset ratios of 1.3 to 1. Without some 

way to alleviate the requirements for the 1991 ozone standard, Northern Virginia, a marginal 

nonattainment area for a much more protective standard, would have much stricter NSR 

requirements than most other marginal and moderate areas in the OTR. The CAA clearly does 

not contemplate this situation. 

Commenter (0132) stated that if a "redesignation substitute" approach is taken, the TCEQ would 

recommend the removal of nonattainment NSR requirements and their replacement with PSD 

requirements for the 2008 ozone NAAQS and all previous standards once an area has met its 

attainment obligations for those previous standards. The commenter believed that the

requirements for a more stringent classification would no longer be in place once an area has 

attained the previous standards. This would allow a state to conduct air permit applicability 

determinations using the classifications associated with the 2008 standard, rather than the most 

stringent classification for areas that did not attain the one-hour and 1997 eight-hour standard 

before the standards were revoked, once those areas reach attainment. This process would be 

consistent with the recommendation that the EPA formally redesignate areas that were 

nonattainment for the previous ozone standards at the time they were revoked, once those areas 

reach attainment for the previous standards. Neither the environment nor the economy benefits 

by retaining classifications and basing permit requirements related to revoked standards, 

particularly once an area has met its obligations for attainment under those standards.

Response: Addressing NSR requirements associated with a revoked ozone NAAQS is a key 

benefit of the flexibility provided by a redesignation substitute mechanism. An area that is 

nonattainment for the 2008 ozone NAAQS that retained anti-backsliding requirements for one 

(or more) revoked ozone NAAQS, whose NSR threshold is set by a revoked NAAQS, can 

address that via the redesignation substitute mechanism. Nonattainment NSR applies in these 

areas in accordance with their highest nonattainment classification under any ozone standard for 

which they are (or were at the time of revocation) designated nonattainment. The redesignation 

substitute mechanism allows a state to demonstrate that the revoked NAAQS which determines 

the threshold level has been attained. Following a successful redesignation substitute showing for 

that NAAQS, the NSR level would then be set by the next higher classification that applies to 

that area. It should be noted that states in the OTR are required to implement, at a minimum, the 

nonattainment NSR requirements associated with a Moderate area.

Once a state develops successful redesignation substitute showings to address anti-backsliding 

requirements for the revoked NAAQS, the nonattainment NSR level remaining is that for the 
238

current ozone NAAQS. The only way to remove nonattainment NSR requirements for the 

current ozone NAAQS is through the standard 107(d)(3)(E) process. Once that is successful, the 

state may shift to implementing PSD in that area.

Comment: Section 185 requirements

Commenter (0132) recommended that this redesignation substitute should also terminate §185 

obligations. Commenter (0151) suggested that if the only planning activity that the EPA feels is 

necessary to preserve is activation of Section 185 penalties for a legacy nonattainment area that 

missed the prior attainment dates, the agency can address that issue without requiring further 

planning and/or a lengthy demonstration of maintenance of the old standard once it is achieved. 

Commenter (0160) supported the proposed approach to remove Section 185 fee program 

obligations if the area has met the 1997 standard and submits a 10-year maintenance showing. 

Response: Terminating section 185 fees associated with a revoked ozone NAAQS is a key 

benefit of the flexibility provided by a redesignation substitute mechanism. The EPA believes 

that an approved redesignation substitute showing is sufficient to terminate these fees, whereas a 

clean data determination or determination of attainment are not. Because an area pursuing the 

redesignation substitute is not redesignating to attainment for the most current NAAQS, the EPA 

believes that a showing that the area can attain the revoked NAAQS for 10 years is a necessary 

part of the successful showing. This complete showing is necessary to demonstrate the area will 

not backslide.

Comment: Streamlined process for removing obligations under prior ozone standards

Commenter (0151) recommended the EPA provide public notice that the EPA made a clean data 

determination in the Federal Register, or even better, maintain a record of such decisions on an 

EPA website in the Ozone NAAQS area. Commenter (0151) recommended that subsequently the 

state should be allowed to petition the EPA to remove former NSR requirements (for formerly 

applicable major source thresholds, offsets, and internal netting) and shift other obligations to its 

contingency plan provided that doing so does not jeopardize progress toward the currently 

applicable NAAQS under Section 110(l). Commenter (0151) stated that additional notice and 

comment activities are not needed; judicial review for such determinations is not warranted; and 

a maintenance demonstration for the former standard for 10 years seems unnecessary, if the area 

has become subject to the 2008 (or a future NAAQS). 

Commenter (0162) supported a streamlined process to minimize the burdens on state and 

industry as they attempt to comply with implementation requirements associated with multiple 

iterations of the ozone NAAQS—1997, 2008, and projected 2014/15 standards. 
239

Response: The EPA publishes all actions in the Federal Register. A list of actions for each 

nonattainment area and their associated FR postings can be found on the EPA’s Green Book 

(http://www.epa.gov/airquality/greenbook/).

Once the EPA approves a redesignation substitute showing for the revoked NAAQS, the state 

can modify the SIP per the usual requirements of section 110(l) and, where appropriate, section 

193. A state that has successfully redesignated from nonattainment to attainment for the current 

ozone NAAQS may shift its preconstruction review permit program from nonattainment NSR to 

PSD.

K. How will the EPA’s determination of attainment (‘‘Clean Data’’) regulation apply for 

purposes of the anti-backsliding requirements?

1. General

Commenter (0166) stated that a determination that an area has “clean data” for the morestringent 2008 NAAQS should be sufficient to lift anti-backsliding requirements for the earlier 

NAAQS. Commenter (0179) supported the proposal to apply the same approach finalized in the 

Phase 1 Rule for the 1997 ozone NAAQS.

Commenter (0181) stated that the legal basis for removal of attainment demonstration 

requirements under the "clean data policy" is equally applicable to anti-backsliding requirements 

for revoked standards and that there is no reason why it should not be applied with respect to 

elimination of anti-backsliding requirements for revoked standards. The commenter believed that 

under the clean data policy, an area that attains the standard is not subject to requirements 

specifically linked with demonstration of attainment and reasonable further progress toward an 

already attained standard. In the Seitz memo, the EPA emphasizes that "this interpretation does 

not extend to requirements of subpart 2 that are not linked by the language of the Act with the 

attainment demonstration and RFP requirements." Requirements such as VOC RACT, which are 

required in designated nonattainment areas without the possibility of exemption through a 

demonstrated lack of need (in contrast with the NOx RACT requirement) are not subject to the 

clean data policy. Because the anti-backsliding requirement is linked by the language of the act 

with the attainment demonstration (and not the attainment designation) it lies within the ambit of 

the clean data policy. The clean data policy has been applied by EPA for decades and has 

withstood court challenges.

Response: The EPA agrees in part with the commenters. A clean data determination for a 

specific ozone NAAQS only suspends planning requirements associated with that specific 

NAAQS, such as attainment demonstration SIPs. It does not suspend mandatory control 

requirements, which could include, as applicable, anti-backsliding requirements associated with 

the revoked NAAQS. As explained in the previous section, the EPA believes that an approved 

redesignation to attainment or a redesignation substitute is necessary to lift anti-backsliding 

requirements associated with a revoked NAAQS. Section 51.1118 clarifies that a clean data 

determination for the 2008 NAAQS acts to suspend planning requirements associated with the 
240

2008 and less stringent 1997 ozone NAAQS, which have an identical form.

2. Section 51.1118

Commenter (0132) stated that the language in proposed §51.1118 requires clarification about 

which ozone standard must be attained in order to suspend SIP planning requirements. The 

commenter believed that this section applies to an area designated nonattainment for the 2008 

ozone NAAQS or for any prior ozone NAAQS, so this section must also specifically indicate 

which ozone NAAQS must be attained in order to suspend planning requirements. According to 

the EPA's proposal, it will no longer redesignate areas to attainment for prior ozone NAAQS

upon revocation of those NAAQS, so it appears that the attainment requirement in §51.1118 is 

meant to be interpreted as attainment of the 2008 NAAQS. However, this language is unclear 

and only states "has attained the standard" rather than more specifically stating "attained the 

2008 ozone NAAQS." If §51.1118 is instead meant to be applied more generally to all ozone 

NAAQS, it should be made clearer. 

Response: Given the request for further clarity about which ozone standard §51.1118 applies to,

the EPA has revised the language in 51.1118 to make it clear that a clean data determination for 

the 2008 NAAQS acts to suspend planning requirements associated with the 2008 and the less 

stringent 1997 ozone NAAQS, which both have the same form. 

L. What is the relationship between implementation of the 2008 ozone NAAQS and the 

CAA Title V permits program?

1. Support for first approach for Title V permitting threshold

Commenters (0132, 0163, 0179 and 180) supported the first option, which sets major source 

Title V thresholds to those applied for RACT and NSR. Commenter (0163) supported option 1 

with the minor conforming amendments to the definition of major source in 40 CFR 70.2 and 

71.2 as detailed on Page 34225. 

Commenter (0132) stated that this approach would provide applicants with clarity and uniformity 

regarding applicable major source thresholds. Commenter (0163) stated that this approach 

maintains the consistency which will ultimately simplify permitting and enforcement. 

Commenter (0163) stated that Option 1 is supported by the fact that these thresholds emanate 

from the same provisions of the CAA (Part D of Title I), therefore, the intent of the CAA was to 

keep the thresholds the same. Commenter (0180) urged the EPA to adopt the first approach, 

because it is consistent with past precedent and compelled by the Act’s anti-backsliding 

requirements as well as court precedent. 

Response: The EPA agrees with these commenters that the major source threshold for title V 

should be the same as the major source threshold for NSR and RACT, and the EPA is finalizing 

the proposed revisions to parts 70 and 71 to make that clear. Following revocation of the 1997 
241

ozone NAAQS, major source thresholds for title V will be the same as the major source 

thresholds applicable for purposes of other requirements, such as RACT and NSR (i.e., the major 

source threshold associated with the more stringent of the area’s classification for the 2008, 1997 

and/or 1-hour ozone NAAQS will be the applicable threshold for title V purposes, to the extent 

that anti-backsliding requirements for the 1997 and/or 1-hour ozone NAAQS apply in the area).

Maintaining consistency between the NSR and title V thresholds in this regard will promote 

compliance with CAA requirements by providing certainty, consistency and a simpler permitting 

regime, ensuring that sources subject to major source NSR understand they are also subject to 

title V, and enabling permitting authorities to identify sources that are potentially subject to 

major source NSR. The EPA believes a contrary approach would introduce not only complexity, 

but anomalies, into the permitting program that would be contrary to the purposes and 

requirements of the Act. To promote effective program implementation and ensure consistency 

with the CAA, this final rule will amend the relevant provisions of parts 70 and 71 related to 

application of title V thresholds.

2. Support for the second approach for Title V permitting threshold

Commenters (0130, 0145, 0152, 0158, 0159 and 0166) supported the second approach, in which 

the major source thresholds for Title V permitting are based solely on an area's classification for 

the 2008 ozone NAAQS.

Commenter (0159) stated that the second approach would provide relief to small operators and 

would adequately reflect the classification under the current ozone NAAQS. Commenter (0130) 

stated that, in this time of resource constraints on both government and private industry, setting 

the Title V permitting thresholds equivalent to thresholds supported by the area's current 

classification for the 2008 ozone NAAQS makes good sense. The commenter believed that Title 

V permits were meant to be a catalogue of all federal requirements that apply to any particular 

facility. Basing the threshold on the classification for a revoked NAAQS, however, would be 

unduly harsh and unnecessary, especially in areas where air quality has met the revoked NAAQS 

for many years. Facilities would need to spend money on the creation of Title V permit 

applications, would need to pay permit fees and emissions fees, and would need to begin semiannual compliance certification reporting. In Virginia, the reduction of the Title V thresholds to 

1-hour severe NSR thresholds would mean at least an additional 40 Title V facilities. These are 

mainly small facilities, and the requirements of Title V would be quite burdensome. 

Additionally, requiring these facilities to comply with Title V mandates would most likely not 

reduce emissions from the units at these facilities.

Commenter (0145) stated that facilities need to renew Title V permits every five years, and by 

the time all facilities have updated their permits to reflect the 2008 ozone NAAQS, it is very 

likely that another ozone NAAQS will have been finalized and permits will again need to be 

modified to reflect this change. 
242

Commenter (0145) also stated that facilities should not have to include a standard that no longer 

exists due to revocation in their Title V operating permits. Commenter (0158) stated that once 

EPA revokes the 1997 ozone standard, and given that the 1-hour standard has already been 

revoked, the major source thresholds for the current standard designations and classifications 

should be the relevant factors for determining whether a source is major for ozone precursors for 

purposes of Title V.

Commenter (0152) stated that the D.C. Circuit's ruling applied only to RACT and NSR and, 

therefore, should not be of concern in this situation, and anti-backsliding provisions should not 

be extended to the Title V program. Commenter (0152) stated that, although the EPA's concern 

is that the D.C. Circuit's ruling stated that the EPA erred in its approach to anti-backsliding by 

not requiring states to retain, as applicable requirements, all control measures that applied for the 

1-hour ozone NAAQS, the Title V program does not create new applicable requirements but 

simply is a permit to consolidate all existing applicable requirements. 

Commenter (0166) stated that the major source thresholds that are redefined due to transition to 

the 2008 NAAQS are for purposes of NSR, not for Title V purposes.

Response: The EPA recognizes that the approach being adopted does not solely rely on the 

area’s current classification for purposes of determining major source thresholds for title V. The 

EPA believes there is ambiguity in the intersection between title V and part D as to whether title 

V should apply the major source threshold of the area’s current classification, or the area’s 

classification for purposes of nonattainment NSR and other underlying applicable requirements, 

when that threshold would be lower. As discussed previously, the EPA believes that it is 

appropriate under the CAA, and consistent with the EPA’s longstanding approach to these 

programs, for a source which is considered to be “major” for purposes of nonattainment NSR to 

also be considered “major” for purposes of title V. For the reasons stated previously, the EPA 

believes maintaining consistency in the major source applicability of the two programs in the 

context of today’s rulemaking, is the best approach to promote consistency and compliance with 

the purposes and requirements of the CAA. 

The EPA is not persuaded by the comments suggesting that the problems with the first approach 

make it necessary to adopt the second approach. The EPA believes this second approach would 

introduce not only complexity, but anomalies, into the permitting program that would be 

contrary to the purposes and requirements of the Act. Areas designated nonattainment for the 

2008 ozone NAAQS and the 1997 ozone NAAQS upon the date the 1997 NAAQS is revoked 

retain anti-backsliding requirements associated with the 1997 ozone NAAQS. Allowing NSR 

levels to rest upon the classification level of the most recent NAAQS does not accurately address 

the requirements from the revoked NAAQS that do not go away with revocation of that NAAQS. 

Areas subject to anti-backsliding requirements for the revoked 1997 ozone NAAQS now have 

two ways to address their thresholds: either formal redesignation to attainment for the 2008 

ozone NAAQS, or the use of a redesignation substitute for the revoked NAAQS. Formal 

redesignation to attainment for the 2008 ozone NAAQS would transition the area from 

nonattainment NSR to PSD. Use of a redesignation substitute to demonstrate that the area has 

attained the revoked NAAQS allows the area to transition NSR levels to the next most stringent 
243

level of NSR – whether those levels are set by the current ozone NAAQS or from another 

revoked ozone NAAQS. The EPA believes that this approach prevents backsliding in the area. 

Where the EPA is at in the review of the current ozone NAAQS does not impact this program.

3. Whether or not Title V is a “control” within the meaning of §172(e)

Comment: Support that Title V is a “control” within the meaning of §172(e)

Commenter (0180) stated that Title V permits represent “controls” for purposes of the Act’s antibacksliding requirements and, as such, the EPA should abide by SCAQMD and use the same 

major source thresholds for administering the Title V permit program as the agency proposes to 

for the NSR and RACT programs. Commenter (0180) stated that Title V permits serve as 

independently enforceable compliance assurance mechanisms that constrain emissions by 

sources and accordingly should be seen as control measures. Commenter (0180) stated that since 

Title V permits collect multiple control requirements in one document, there is no reason for the 

agency to depart from SCAQMD and treat Title V permitting classifications differently than, for 

example, NSR or RACT permitting. Commenter (0180) cited SCAQMD and suggested that Title 

V should be considered a control measure because it is highly improbable that if Title V were not 

present there would be no effect on ozone levels. Commenter (0180) also stated that since both 

NSR and Title V restrictions increase as the nonattainment classification worsen, these identical 

structures underscore the importance of treating Title V as a control for purposes of the Act’s 

anti-backsliding requirements. 

Comment: Support that Title V is not a “control” within the meaning of §172(e)

Commenters (0132, 0145, 0151, 0152, 0159, and 0179) stated the Title V program is not a 

control in and of itself. Commenter (0132) stated that the EPA has consistently stated that Title 

V is a separate program when compared to the requirements of Title I. Commenter (0152) stated 

that the history of Title V rulemaking is clear on this point. Commenter (0179) stated that Title V 

is not a control since the EPA has stated repeatedly that no substantive controls are imposed 

simply by having a Title V permit. Commenter (0145) stated that Title V should not be 

considered a “control” in light of the fact that Title V is not intended to impose new substantive 

air quality control requirements but is instead intended to assure compliance with all existing 

applicable requirements. Commenter (0151) stated that the legislative history of the 1990 CAA 

Amendments is clear that Title V is an administrative means of collecting substantive applicable 

control requirements under the CAA in a single document; therefore, the requirement for a Title 

V permit is not itself a “control requirement.”
244

Response: It is not necessary to resolve this question at this time, because the purposes and 

requirements of the CAA Section 172(e) are fulfilled by establishing title V permitting 

thresholds to be the same as the permitting thresholds for underlying applicable requirements, 

particularly NSR. Since the EPA is taking final action adopting the interpretation that major 

source definitions should be the same for both programs, the above-described issue does not 

need to be resolved at this time.
245

4.0 Statutory and Executive Order Reviews

A. Environmental Justice 

Comment: Commenter (0180) cited Executive Order 12898 and stated the EPA’s analysis does 

not look at the relevant question: whether this rule disproportionately affects minority and lowincome populations. Commenter (0180) stated that, if ozone nonattainment areas cover 

disproportionately large minority and low-income populations, it is irrelevant that NAAQS are 

designed to protect all segments of the population, it is the effects, not the intent, that matters. 

Commenter (0180) referenced two EPA studies and stated that greater percentages of racial 

minorities than of white populations lived in ozone nonattainment areas in the early 1990s and 

that there is evidence of an increase in risk of O3-related health effects for Blacks and Hispanics 

and people with lower socioeconomic status. Commenter (0180) objected to the lack of analysis 

as to what the policy decisions in the rule mean for prompt attainment of the ozone standards.

Response: The EPA conducted a proximity analysis, as part of the NAAQS review, that 

examined socio-demographic attributes of populations in counties currently exceeding the 

proposed ozone standards (2011 – 2013 design value). Results show that the percent of minority, 

Hispanic, and low income populations in counties most likely to benefit from reductions in 

ozone concentrations is similar to national averages. However, because we do not know the 

distribution of emissions following the rule we are unable to provide an analysis of changes in 

the distribution of outcomes following the implementation of the rule.

The following two tables are from the RIA36 for the ozone NAAQS review.

 

36 Regulatory Impact Analysis of the Proposed Revisions to the National Ambient Air Quality 

Standards for Ground-Level Ozone, November 2014, available at 

http://www.epa.gov/ttn/ecas/regdata/RIAs/20141125ria.pdf
246

Table 9-1. Summary of Population Totals and Demographic Categories for Areas of 

Interest and National Perspective

Demographic 

Summary Population White

African 

American

Native 

American

Other or 

Multiracial[1]

Minority/NonWhite

Hispanica

Area of Interest Total

 65 ppb 221,431,286 153,706,027 30,429,108 1,726,110 35,570,041 67,725,259

 70 ppb 193,316,836 132,112,738 27,193,155 1,488,364 32,522,579 61,204,098

% of Area of Interest Total

 65 ppb 69% 14% 1% 16% 31%

 70 ppb 68% 14% 1% 17% 32%

National 

Total 312,861,256 226,405,205 39,475,216 2,952,087 44,028,748 86,456,051

% of 

National 

Total 72% 13% 1% 14% 28%

a The race Minority/Non-White Hispanic field is computed by subtracting the white population from the total 

population.

Table 9-2. Summary of Population Totals and Demographic Categories for Areas of 

Interest and National Perspective

Demographic 

Summary

Linguistically 

Isolated Age 0 – 4 Age 0 - 17 Age 65+

Without a 

HS Diploma

Low 

Income[2]

Area of Interest Total

 65 ppb 13,072,109 14,695,948 54,008,810 27,163,990 20,914,891 67,027,700

 70 ppb 12,179,896 12,849,637 47,296,147 23,518,071 18,495,474 58,296,224

% of Area of Interest Total

 65 ppb 6% 7% 24% 12% 14% 30%

 70 ppb 6% 7% 24% 12% 15% 30%

National Total 19,196,507 20,465,065 75,217,176 40,830,262 30,952,789 101,429,436

% of National 

Total 6% 7% 24% 13% 15% 32%

 

[1] Appendix 9A clarifies that “other or multiracial” is derived from individual reporting on 

Census forms and includes citations to the specific 2010 Census data used in this analysis.

[2] Appendix 9A clarifies that “low income” in this analysis is defined as income two times the 

poverty line or less. 
247

5.0 Other Comments

A. General

1. Improving the CAA

Comment: Commenter (0119) questioned whether the final rule should discuss the possibility of 

improving the CAA to create a mechanism to more simply, efficiently, and effectively achieve 

the new standard. 

Response: Since the CAA was put into place more than 40 years ago the CAA has experienced 

many accomplishments such as: cut pollution as the US economy has grown, environmental 

damage from air pollution has been reduced; Americans breathe less pollution and face lower 

risk of premature death and other Serious health effects; and environmental damage from air 

pollution is reduced. The EPA is aware that since the CAA was last amended in 1990s there has 

been discussion over the years in Congress about amending the CAA. The EPA also recognizes 

that the knowledge of air pollution has evolved over the years.

2. Most proposed rule elements are unnecessary

Comment: Commenter (0151) stated that most of the elements of the proposed rule are 

unnecessary because the 2008 ozone NAAQS is the same as the 1997 standard, just more 

stringent. Commenter (0151) stated that the EPA’s principal concern should be preventing 

backsliding (i.e., removal of SIP requirements adopted under section 182(b) which have been 

approved), rather than requiring states to replicate planning and maintenance activities for the 

1997 ozone standard, which should logically be directed at planning for attainment of the 2008 

(and then, the expected 2014) ozone NAAQS. 

Response: The EPA is considering ways rules are written so that the reading experience is 

improved. One way to accomplish this goal is to highlight rule elements that change only and 

keep the historical and background information stagnant. Another way this could be 

accomplished it so provide a summary of areas we are seeking comment on with associated page 

number.

3. Menu of Control Measures

Comment: Commenter (0152) stated that the EPA references an updated 2012 "Menu of Control 

Measures" available at http://www.epa.gov/airquality/ozonepollution/SIPToolkit/, but they are 

unable to locate this document at the referenced website.
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Response: The EPA appreciates the commenter pointing out this error. In the final rule, the 

“Menu of Control Measures for NAAQS Implementation” web address will be indicated as: 

http://www.epa.gov/air/criteria.html

B. Support for other commenters

Commenter (0174) supports the comments submitted by commenters (0151).

Commenter (0162) supports the comments submitted by commenters (0122 and 0166)

C. Codification error

Comment: Page 34238

Commenter (0169) noted a codification error on page 34238 of the proposed SIP Requirements 

Rule:

"(a) Baseline emissions inventory for RFP plans," should be codified as 51.1110(b). 

Currently codified items 51.1110(b) through 51.1110(d) should be recodified as 

51.1110(c) through 51.1110(e). Item 51.1110(e) is even referenced in 51.1110(a)(5), but 

no 51.l110(e) currently exists in the proposed rule text. 

Commenter (0166) similarly stated that the subsections of § 51.1110 are mis-numbered, with two 

subsections enumerated “(a).”

Response: The EPA has reviewed the language in the proposal and has discovered numbering 

errors. Corrected numbering of the section will appear in the final rule.

Comment: RFP requirements

Commenter (0166) stated that the proposed regulatory language on RFP requirements conflicts 

internally and explained as follows: If the EPA decides to retain the language of proposed 40 

CFR § 51.1110, it will need to reconcile the provisions of the first subsection (a), which states 

that “[t]he RFP requirements specified in CAA section 182 for that area’s classification shall 

apply,” with subsection (a)(2), which indicates that those section 182 requirements do not in fact 

apply to Moderate and above nonattainment areas that have an approved VOC RFP plan for a 

prior ozone NAAQS (or have a determination of attainment).

Response: The EPA appreciates the commenter’s suggestion and has reviewed the language and 

believes the reference to be correct. CAA section 182 provides requirements for nonattainment 

areas of all classifications and is therefore appropriate.

D. Los Angeles-South Coast Air Basin

Commenter (0176) made the following suggestions:
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The Challenge to Ozone Implementation is a challenge to the built urban environment. 

Los Angeles-South Coast Air Basin Area is EXTREME.

How do we control air quality when land use planning is not a federal issue. Instead,

Transit Oriented Development with bus and rail were developed as an answer.

Your concentration on vehicles dissuades you from approaching those conditions of 

density. We are now faced with more density, more vehicles and a poor transit class.

Transportation patterns with jobs and housing were never identified. It is near impossible 

in the second largest city in the country-the City of Los Angeles.

Throw out Transportation Plans when you have no basis in reality for them.

Approach Land Use designations with as much intensity as vehicles. Air rights are an 

issue as they allow Signage and especially digital signage. The contributors to ozone need 

proper identification.

Oil and gas fields, whether currently drilled or capped is an issue. In the City of Los 

Angeles, where the old oil fields were never identified and we cannot rely on any 

paperwork to show proper capping, outgassing is an issue. With the flir cameras, that can 

be identified. It is not required even when levels are near explosive.

What is the effect of fracking aka hydraulic fracturing.

Are landfills accepting hazardous (medical) waste.

Measure the air around these concentrated areas.

Few monitoring stations exist. Source points are not identified. It is just assumed that the 

vehicle is the culprit.

Look at the railroads and their rules for maintenance. You may need to work 

cooperatively with the FRA Federal Railroad Administration on their rules over engines.

We have that problem with the Metrolink Maintenance Yard near Downtown Los 

Angeles. There is no state jurisdiction over their Air Quality and no SIP can be 

implemented

Analyze weather patterns. We see no discussion on that aspect of air movement.

Any modeling needs to be regionally specific.

We do not find that the Regional Air Quality Management Districts’ outreach to the 
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public sufficiently or engage elected officials to understand the requirements of the CAA. 

In other words, what financial effect is assigned to non-attainment.

Credit reductions are a financial instrument as is FAR Floor Area Ratio rights.

Offset Credits from any outside area does not change the health effects on persons, 

animals, wildlife, birds, plants and property.

The financial game is not the way to approach attainment.

Response: The EPA neither agrees nor disagrees with this commenter’s comments. We do not 

see any comments that are relevant to the rulemaking under consideration, for example, the 

suggestion to “throw out” transportation plans.

Also, the EPA cannot decipher what the commenter means in several instances, for example, 

regarding signage, digital signage, and land use designations, nor how that might relate to what 

the commenter refers to as air rights. 

Further, the EPA believes that the commenter is working under the mistaken understanding that 

the rulemaking under consideration contains an air quality plan. It does not. On the contrary, this 

rulemaking sets requirements for air quality planning that will be done at the state and local 

level, with multiple opportunities for public input. Comments about pollutant emissions from 

specific industrial sources, such as oil and gas fields or railroads, as well as modeling and 

monitoring of air pollutants and the weather patterns in a particular nonattainment area, would 

more appropriately be directed to the relevant state or local agency in the context of the air 

quality planning for that area, or in the context of any air permitting process that specific sources 

need to undergo. 

The commenter’s concerns regarding the extent to which local air districts engage the public or 

elected officials is not germane to this current rulemaking. However, when the state and local air 

agencies prepare air quality plans for a particular nonattainment area, as required under this 

rulemaking, they are required to follow certain minimum requirements regarding public 

outreach. Proof that this obligation has been met must also accompany any air quality plans 

submitted to the EPA. Furthermore, when the EPA proposes to take action on such plan 

submittals, the EPA follows federal requirements for public outreach.

The EPA believes that the commenter has misunderstood several phrases in the rule proposal. 

What the commenter refers to as “credit reductions” and seems to interpret as a reference to 

financial terminology seems to be actually a reference to creditable pollution emission 

reductions. Likewise, the commenter uses the phrase “offset credits from any outside area,” and 

apparently concludes that such a financial activity does not improve human health and the 

environment. However, the EPA believes that the phrase the commenter is responding to is 

actually a reference to the EPA’s proposal to require that the pollutant emissions reductions 

required by the CAA in a nonattainment area must occur within that area and cannot be credited 

from an outside area. The EPA anticipates that, had the commenter understood this aspect of the 

proposal, the commenter would not have raised objections to what the commenter perceived as 
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some form of financial regulation.

Regardless of any possible misunderstanding on the part of the commenter between pollution 

credits and credit in the financial sense, the EPA nonetheless wants to clarify for the commenter 

that the costs of responding to a nonattainment designation is largely dependent upon methods 

that the state and local air agencies determine are best to address the air quality problem in the 

area.