*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 1 of 40 

 6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Parts 50 and 51 

[EPA-HQ-OAR-2010-0885, FRL- ] 

RIN 2060-AP24 

Implementation of the 2008 National Ambient Air Quality Standards for Ozone: Nonattainment 

Area Classifications Approach, Attainment Deadlines and Revocation of the 1997 Ozone 

Standards for Transportation Conformity Purposes 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The EPA is proposing thresholds for classifying nonattainment areas for the 2008 ozone 

National Ambient Air Quality Standards (NAAQS) (the “2008 ozone NAAQS”) promulgated by the 

EPA on March 12, 2008. This proposal also addresses the timing of attainment dates for each 

classification. Finally, we are proposing to revoke the 1997 ozone NAAQS 1 year after the effective date 

of designations for the 2008 ozone NAAQS for transportation conformity purposes only. 

DATES: Comments. Comments must be received on or before [INSERT DATE 45 DAYS FROM 

DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

Public Hearings. One public hearing concerning the proposed regulation will be held on January 13, 

2012. Please refer to SUPPLEMENTARY INFORMATION for additional information on the 

comment period and the public hearing. 

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2010-0885, by one 

of the following methods: 

• www.regulations.gov: Follow the on-line instructions for submitting comments. 

• Email: a-and-r-docket@epa.gov
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 2 of 40 

• Mail: Air and Radiation Docket and Information Center, Attention Docket ID No. EPA-HQ-OAR2010-0885, Environmental Protection Agency, 1301 Constitution Ave., NW, Washington, D.C. 

20460. Mail Code: 2822T. Please include two copies if possible. In addition, please mail a copy of 

your comments on the information collection provisions to the Office of Information and Regulatory 

Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th St. NW, 

Washington, D.C. 20503. 

• Hand Delivery: Air and Radiation Docket and Information Center, Attention Docket ID No. EPAHQ-OAR-2010-0885, Environmental Protection Agency in the EPA Headquarters Library, Room 

Number 3334 in the EPA West Building, located at 1301 Constitution Ave., NW, Washington, D.C. 

The EPA/DC Public Reading Room is open from 8:30 a.m. to 4:30 p.m. Eastern Standard Time 

(EST), Monday through Friday, Air and Radiation Docket and Information Center. 

Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2010-0885. The EPA's 

policy is that all comments received will be included in the public docket without change and may be 

made available on-line at www.regulations.gov, including any personal information provided, unless the 

comment includes information claimed to be confidential business information (CBI) or other 

information whose disclosure is restricted by statute. Do not submit information that you consider to be 

CBI or otherwise protected through www.regulations.gov or email. The www.regulations.gov website is 

an “anonymous access” system, which means the EPA will not know your identity or contact 

information unless you provide it in the body of your comment. If you send an email comment directly 

to the EPA without going through www.regulations.gov, your email address will be automatically 

captured and included as part of the comment that is placed in the public docket and made available on

the Internet. If you submit an electronic comment, the EPA recommends that you include your name and 

other contact information in the body of your comment and with any disk or CD-ROM you submit. If 

EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 3 of 40 

EPA may not be able to consider your comment. Electronic files should avoid the use of special 

characters, any form of encryption, and be free of any defects or viruses. For additional information 

about the EPA’s public docket, visit the EPA Docket Center homepage at 

http://www.epa.gov/epahome/dockets.htm. For additional instructions on submitting comments, go to 

the SUPPLEMENTARY INFORMATION section of this document. 

Docket: All documents in the docket are listed in www.regulations.gov. Although listed in the index, 

some information is not publicly available, i.e., CBI or other information whose disclosure is restricted 

by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be 

publicly available only in hard copy form. Publicly available docket materials are available either 

electronically in www.regulations.gov or in hard copy at the Air and Radiation Docket and Information 

Center in the EPA Headquarters Library, Room Number 3334 in the EPA West Building, located at 

1301 Constitution Ave., NW, Washington, D.C. The Public Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public 

Reading Room is (202) 566-1744. 

FOR FURTHER INFORMATION CONTACT: For further general information on this rulemaking, 

contact Dr. Karl Pepple, Office of Air Quality Planning and Standards, U.S. Environmental Protection 

Agency (C539-01), Research Triangle Park, NC 27711, phone number (919) 54l-2683, fax number 

(919) 54l-0824 or by email at pepple.karl@epa.gov or Mr. Butch Stackhouse, Office of Air Quality 

Planning and Standards, U.S. Environmental Protection Agency (C539-01), Research Triangle Park, NC 

27711, phone number (919) 54l-5208, fax number (919) 54l-0824 or by email at 

stackhouse.butch@epa.gov. For information on the public hearing or to register to speak at the public 

hearing, contact Ms. Pamela S. Long at (919) 541–0641 or by email at long.pam@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. General Information 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 4 of 40 

A. Does this action apply to me?

Entities potentially affected directly by the proposed rule for this action include state, local, and 

tribal governments. Entities potentially affected indirectly by the proposed rule include owners and 

operators of sources of emissions [volatile organic compounds (VOCs) and nitrogen oxides (NOx)] that 

contribute to ground-level ozone concentrations. 

B. What should I consider as I prepare my comments for EPA?

 1. Submitting CBI. Do not submit this information to the EPA through www.regulations.gov or 

email. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a 

disk or CD ROM that you mail to the EPA, mark the outside of the disk or CD ROM as CBI and then 

identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In 

addition to one complete version of the comment that includes information claimed as CBI, a copy of 

the comment that does not contain the information claimed to be CBI must be submitted for inclusion in

the public docket. Information so marked will not be disclosed except in accordance with procedures set 

forth in 40 CFR part 2. 

2. Tips for Preparing Your Comments. When submitting comments, remember to: 

• Identify the rulemaking by docket number and other identifying information (subject heading, 

Federal Register date and page number). 

• Follow directions - The agency may ask you to respond to specific questions or organize comments 

by referencing a Code of Federal Regulations (CFR) part or section number. 

• Explain why you agree or disagree; suggest alternatives and substitute language for your requested 

changes. 

• Describe any assumptions and provide any technical information and/or data that you used. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 5 of 40 

• If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient 

detail to allow for it to be reproduced. 

• Provide specific examples to illustrate your concerns, and suggest alternatives. 

• Explain your views as clearly as possible, avoiding the use of profanity or personal threats. 

• Make sure to submit your comments by the comment period deadline identified. 

C. Where can I get a copy of this document and other related information?

 In addition to being available in the docket, an electronic copy of this notice will be posted at 

http://www.epa.gov/air/ozonepollution/actions.html#impl under “recent actions.” 

D. What should I know about the public hearing?

 The public hearing will be held on January 13, 2012 at the [location] at [time.] It will convene at 

X:XX a.m. and end at X:XX.p.m. or until the last registered speaker has spoken. If you would like to 

speak at this public hearing, please contact Ms. Pamela Long no later than 5:00 p.m. on January 11, 

2012. 

The public hearing will provide interested parties the opportunity to present data, views, or 

arguments concerning the proposal. The EPA may ask clarifying questions during the oral presentations,

but will not respond to the presentations at that time. Written statements and supporting information 

submitted during the comment period will be considered with the same weight as any oral comments 

and supporting information presented at the public hearing. Written comments on the proposed rule 

must be postmarked by [INSERT DATE 45 DAYS FROM DATE OF PUBLICATION IN THE 

FEDERAL REGISTER]. 

Commenters should notify Ms. Long if they will need specific equipment, or if there are other 

special needs related to providing comments at the hearings. The EPA will provide equipment for 

commenters to show overhead slides or make computerized slide presentations if we receive special 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 6 of 40 

requests in advance. Oral testimony will be limited to 5 minutes for each commenter. The EPA 

encourages commenters to provide EPA with a copy of their oral testimony electronically (via email or 

CD) or in hard copy form. 

The hearing schedules, including lists of speakers, will be posted on the EPA’s website at 

http://www.epa.gov/air/ozonepollution/actions.html#impl. Verbatim transcripts of the hearings and 

written statements will be included in the docket for the rulemaking. 

The EPA will make every effort to follow the schedule as closely as possible on the day of the 

hearings; however, please plan for the hearing to run either ahead of schedule or behind schedule. For

updates and additional information on the public hearing, please check the EPA’s website for this 

rulemaking at http://www.epa.gov/ozonepollution/actions.html. 

E. How is this notice organized? 

The information presented in this notice is organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. What should I consider as I prepare my comments for EPA? 

C. Where can I get a copy of this document and other related information? 

D. What should I know about the public hearing? 

E. How is this notice organized? 

II. Background for Proposal 

A. Overview 

B. History of Nonattainment Area Classification Systems for the Ozone NAAQS 

C. Initial Area Designations for the 2008 Ozone NAAQS 

D. Transportation Conformity and the 1997 Ozone NAAQS 

III. What are the proposed classification thresholds for nonattainment areas for the 2008 ozone 

NAAQS? 

A. Proposed Classification Thresholds 

B. Reclassification of Nonattainment Areas That Have Voluntarily Requested Higher 

Classifications 

C. What are we proposing as the attainment deadlines for nonattainment areas in each 

classification of the 2008 ozone NAAQS? 

IV. What is the EPA proposing regarding revocation of the 1997 ozone NAAQS at this time? 

 A. What is the background for our proposal? 

 B. What is the rationale for our proposal? 

 C. Why is it necessary to revoke the 1997 ozone NAAQS now for transportation conformity 

purposes? 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 7 of 40 

 D. Is the EPA proposing to revoke the 1997 ozone NAAQS for other purposes as part of this 

rulemaking? 

V. What does this rulemaking not address? 

VI. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: 

Improving Regulation and Regulatory Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments 

G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks 

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy 

Supply, Distribution, or Use. 

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations 

K. Determination under Section 307(d) 

VII. Statutory Authority 

LIST OF SUBJECTS 

II. Background for Proposal

A. Overview

On March 12, 20081, the EPA revised the primary National Ambient Air Quality Standards 

(NAAQS) for ozone to a level of 0.075 parts per million (ppm) (annual fourth-highest daily maximum 

8-hour concentration, averaged over 3 years).2,3 On July 16, 2009, the EPA announced that it would 

initiate a rulemaking to reconsider the standard for various reasons, including the fact the 0.075 ppm

level fell outside of the range recommended by the Clean Air Scientific Advisory Committee. Pending 

the outcome of that reconsideration, the EPA suspended further work on designating areas, including 

developing a classification approach for areas that would be designated nonattainment. In September 

2011, the Office of Management and Budget (OMB) returned for further consideration the EPA’s draft 

 

1

 See 73 FR 16436. 

2

 The secondary ozone standard, designed to protect public welfare, was set at the same level and with 

the same averaging time as the primary standard. 

3

 For a detailed explanation of the calculation of the 3-year 8-hour average, see 40 CFR part 50, 

Appendix I. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 8 of 40 

rulemaking to reconsider the 2008 ozone NAAQS.4

 The current NAAQS for ozone thus remains at 

0.075 ppm, as established in 2008. The 2008 NAAQS retains the same general form and averaging time 

as the 0.08 ppm NAAQS set in 1997 but is set at a more stringent level.5 

While the 2008 NAAQS was being reconsidered, the EPA deferred initial designation of areas as 

attainment or nonattainment with respect to that standard until March 12, 2011.6

 (See 75 FR 2936.) 

Since this deadline has passed and the EPA’s draft rulemaking to reconsider the 2008 ozone NAAQS 

has been returned by OMB for further consideration, the EPA is now proceeding with certain activities 

to implement the 2008 ozone NAAQS. In a separate action, the EPA will propose a rule to address the 

steps states will take to implement the NAAQS and the timing of those steps. In this action, we address 

the system for classifying nonattainment areas and a limited set of additional implementation issues. 

A key first step after promulgating a new or revised NAAQS is for the EPA to issue initial area 

designations. Following the schedule provided in Clean Air Act (CAA) section 107(d), states were 

required to submit designation recommendations for every area of each state to the EPA by March 12, 

2009, which was 1 year after the promulgation date of the 2008 ozone NAAQS. The EPA has received 

these recommendations and intends to proceed with the designations process based on these 

recommendations. 

In accordance with CAA section 181(a)(1), the classification for each ozone nonattainment area 

will be established by operation of law at the same time as the area is designated by the EPA. Therefore, 

the EPA intends to finalize classification thresholds on or before the date that initial area designations 

are issued by the Administrator. 

 

4

 Memorandum from Cass R. Sunstein to Administrator Lisa Jackson, dated September 2, 2011. 

5

 Note that the 2008 NAAQS is based on a different rounding convention than the 1997 NAAQS. 

6

 The 2008 ozone NAAQS was promulgated on March 12, 2008. By the 2-year designation requirement 

found in CAA §107(d)(1), the deadline for designating areas was March 12, 2010. The EPA determined 

that due to the reconsideration there was insufficient information to designate areas, and invoked the

additional year for designations as allowed under CAA §107(d)(1)(B). 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 9 of 40 

 Under Subpart 2 of part D of title I of the CAA, state planning and emissions control 

requirements for ozone are determined, in part, by a nonattainment area’s classification. In 1990, 

Congress amended part D of title I of the CAA by adding several new subparts, including subpart 2, 

which specifies implementation requirements for ozone nonattainment areas. These requirements apply 

in addition to the general State Implementation Plan (SIP) planning requirements applicable to all 

nonattainment areas under subpart 1 of part D. Under subpart 2, ozone nonattainment areas are classified 

based on the severity of their ozone levels (as determined based on the area’s “design value,” which 

represents the most recent 3-year average of the air quality in the area)7

. Nonattainment areas with a 

“lower” classification have ozone levels that are closer to the standard than areas with a “higher” 

classification. The subpart 2 classification section provides an increasing amount of time from the date 

of designation to attain the standards for the progressively higher classifications: Marginal (3 years), 

Moderate (6 years), Serious (9 years), Severe-15 (15 years), Severe-17 (17 years), and Extreme (20 

years). 

Areas in the lower classification levels have fewer and/or less stringent mandatory air quality 

planning and control requirements than those in higher classifications. For instance, Marginal areas are 

exempt from the requirement to prepare an attainment demonstration and associated contingency 

measures, although such areas are required to adopt an emissions statement rule for stationary sources, 

submit a baseline emissions inventory, and implement a nonattainment area preconstruction permit 

program. A Moderate area needs to comply with the Marginal area requirements; in addition the state 

must submit a demonstration that the area will attain within 6 years after designation, and it must adopt 

(and submit for EPA approval) certain emissions control requirements, such as reasonably available 

control technology, a basic vehicle inspection and maintenance program if the area meets the applicable 

 

7

 The air quality design value for the 8-hour O3 NAAQS is the 3-year average of the annual 4th highest 

daily maximum 8-hour average ozone concentrations.”
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 10 of 40 

population thresholds, and provisions for increased offsets for new or modified sources under the state’s 

new source review (NSR) program. The higher classifications similarly require additional emissions 

controls and stricter NSR offset requirements beyond those required for a Moderate area. In addition, 

under the higher classifications, smaller sources are considered “major sources” for permitting and other 

requirements. 

B. History of Nonattainment Area Classification Systems for the Ozone NAAQS

 The CAA was amended in 1990 to add specific provisions that apply to ozone nonattainment 

areas. These include timelines for both planning and implementation, and requirements for specific 

programs to reduce emissions that vary based on an area’s classification. The ozone standard that was in 

effect at the time of the 1990 CAA amendments was a 1-hour exceedance-based standard of 0.12 ppm.8

Accordingly, the classification provisions in Table 1 in section 181 of subpart 2 of the CAA (also 

referred to herein as the “subpart 2 classification table”) are specific to that 1-hour standard. In 1997, the 

EPA revised both the form and level of the ozone NAAQS to a 3-year average of daily maximum 8-hour 

averages.9 In a subsequent rulemaking, the EPA adapted the CAA’s 1-hour classification thresholds to 

the new 8-hour standard10 and used the new 8-hour threshold values to classify certain areas designated 

nonattainment for the 1997 8-hour NAAQS. This approach for translating the CAA’s 1-hour threshold 

values to 8-hour threshold values was challenged in litigation and was upheld by the court. See South 

Coast Air Quality Management District v. Environmental Protection Agency, 472 F.3d at 896-898. 

C. Initial Area Designations for the 2008 Ozone NAAQS

 Under CAA §107(d), initial area designations are required when a NAAQS is revised. The 

process involves interaction between the EPA and states, starting with states preparing recommendations 

and submitting them to the EPA for review. If the EPA intends to modify a state’s recommendation, the 

 

8

 For additional detail on the 1-hour ozone NAAQS, see 56 FR 56694. 

9

 See 40 CFR Appendix I. 

10 Referred to as the Phase 1 Rule, see 40 CFR Part 51, Subpart X at 51.903. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 11 of 40 

EPA must notify the state of such modification by letter no later than 120 days (“120 day letters”) prior 

to making a final decision.11 For the 2008 ozone NAAQS, most states submitted designation 

recommendations to the EPA as required under section 107(d) in March 2009, 1 year after the 2008 

NAAQS was promulgated. States also had the opportunity to update these recommendations in the fall 

of 2011, based on ambient air quality monitoring data for the years 2008-2010, which were (and still 

are) the most recent monitoring data available. 

 The EPA plans to consider the state recommendations received in 2009 and any updates 

provided by the states based on current monitoring data in deciding whether to modify any 

recommendations. In the event that the EPA intends to modify a state’s recommendation, the EPA will 

notify the state 120 days prior to issuing designations. The EPA’s goal is to finalize designations by

mid-2012. 

D. Transportation Conformity and the 1997 Ozone NAAQS

 In this rulemaking, the EPA is proposing to revoke the 1997 ozone NAAQS for transportation 

conformity purposes only. The revocation of the 1997 ozone standard for this limited purpose would 

occur 1 year after the effective date of initial area designations for the 2008 ozone NAAQS. We believe 

this approach is the most logical because it would result in only one ozone NAAQS – the more 

protective 2008 ozone NAAQS – applying for purposes of transportation conformity, after the end of the

1-year transportation conformity grace period that applies to newly designated nonattainment areas (see

CAA section 176(c)(6)). If the 1997 ozone NAAQS were to remain in place after conformity applies for 

the 2008 ozone NAAQS, areas currently in nonattainment or maintenance for the 1997 ozone NAAQS 

that are designated nonattainment for the 2008 ozone NAAQS would be required to implement the 

 

11 While CAA section 107, which governs the process for initial area designations, specifically addresses 

states, the EPA intends to follow the same process for tribes to the extent practicable, pursuant to section 

301(d) of the CAA regarding tribal authority and the Tribal Authority Rule (63 FR 7254; February 12, 

1998). The EPA is working with the tribes and tribal organizations regarding their participation in the 

designations process. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 12 of 40 

transportation conformity program for both ozone NAAQS concurrently. The EPA is proposing to 

revoke the 1997 ozone NAAQS for purposes of transportation conformity in an attempt to avoid this 

overlap of NAAQS for conformity requirements. The EPA intends to discuss potential revocation of the 

1997 NAAQS for other purposes in a future, separate rulemaking. 

III. What are the proposed classification thresholds for nonattainment areas for the 2008 ozone 

NAAQS? 

A. Proposed Classification Thresholds

 1. Background 

 The subpart 2 classification table includes the classification thresholds for areas designated as 

nonattainment for the 1-hour ozone NAAQS. The subpart 2 classification table is based on 1-hour ozone 

nonattainment area design values (DVs) (i.e., beginning at a level of 0.121 ppm) because it was designed 

for implementation of the 0.12 ppm 1-hour standard, which was the effective ozone standard when 

Congress added the table to the CAA in 1990. Because the table is based on DVs for a 0.12 ppm 1-hour 

standard, we recognized in the rulemaking to implement the 1997 NAAQS that it did not make sense to 

apply the thresholds listed in the table for implementing the 1997 0.08 ppm 8-hour standard. The EPA 

believed that using 8-hour DVs to classify areas for the 8-hour standard would reflect the magnitude of 

the 8-hour ozone problem more accurately than would using the 1-hour DVs in the subpart 2 

classification table. In addition, many of the areas that were nonattainment for the 1997 8-hour NAAQS

had 1-hour DVs less than 0.121 ppm and would not have been covered by the subpart 2 classification 

table at all. 

 We adopted by regulation a modified version of the subpart 2 classification table for the 1997 8-

hour ozone standard which contains 8-hour DV thresholds for each classification, rather than the 

statutory 1-hour DV thresholds. We translated the classification thresholds in the subpart 2 classification 

table from 1-hour DVs to 8-hour DVs based on the percentage by which each classification threshold in 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 13 of 40 

the table exceeds the 1-hour ozone NAAQS. We noted that these percentages, as established by 

Congress in 1990, set the classification thresholds at certain percentages or fractions above the level of 

the standard.12 We refer to this method as the “percent-above-the-standard” method. We are proposing 

to take the same approach for the 2008 ozone NAAQS. As we did for the 1997 8-hour NAAQS, we are 

proposing to establish by regulation a modified version of this classification table to account for the new 

level of 0.075 ppm as compared to the level of 0.08 ppm used to establish the classification table for the 

1997 ozone NAAQS. 

As we did for the 1997 NAAQS, the EPA analyzed various alternative options for establishing 

thresholds for classifications for the 2008 ozone NAAQS. However, we are proposing to use the same 

“percent-above-the-standard” methodology as was used for the 1997 ozone standard.13 Options that 

were evaluated other than the one we are proposing are discussed briefly below and described in more 

detail in a background information document14 in the docket to this rulemaking. 

The percent-above-the-standard method is a simple and straightforward method for establishing 

classification thresholds that is based on principles inherent in the subpart 2 classification table itself. 

The principles include the following: 

• Areas are grouped by the severity of their air quality problem as characterized by the degree of 

nonattainment based on their DV. 

• Classification would occur “by operation of law” without relying on EPA exercising discretion for 

individual situations (prior to any application of the 5 percent adjustment provision under section 

 

12 The upper thresholds of the Marginal, Moderate, Serious, and Severe classifications are precise 

percentages or fractions above the level of the standard, namely 15 percent (3/20ths more than the 

standard), 33.33 percent (one-third more than the standard), 50 percent (one-half more than the 

standard), and 133.3 percent (one and one-third more than the standard). 

13 Background Information Document: Hypothetical Nonattainment Areas for Purposes of 

Understanding the EPA Proposed Rule for Implementing a 2008 8-Hour Ozone National Ambient Air 

Quality Standard--Illustrative Analysis Based on 2010 Design Values. December 2011.

14 Background Information Document: Additional Options Considered for Classification of 

Nonattainment Areas under the 2008 Ozone NAAQS. December 2011.
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 14 of 40 

181(a)(4)). See section III.B of this rule for additional details on how EPA intends to address 

previous requests for voluntary bump-ups for the 1997 ozone NAAQS. 

• Classification thresholds are derived from the structure or logic of the CAA’s nonattainment area 

planning and control requirements, including the subpart 2 classification table, and consistent with 

the overall goal of subpart 2 of attaining the standards as expeditiously as practicable. 

 2. Proposed Classification Threshold Method – Percent-Above-the-Standard Method

 In this section, we describe the EPA’s proposed methodology for establishing classification 

thresholds for purposes of classifying ozone nonattainment areas with respect to the 2008 ozone 

NAAQS. Using this approach for the 2008 NAAQS, the classification thresholds in the subpart 2 

classification table would be translated into a corresponding set of 8-hour DVs by setting threshold DVs 

in the new table at the same percentages above the 2008 ozone NAAQS as the DV levels in the subpart 

2 classification table are above the 1-hour ozone NAAQS. For example, the threshold separating the 

Marginal and Moderate classifications in the subpart 2 classification table (0.138 ppm) is 15 percent 

above the 1-hour ozone NAAQS (0.12 ppm). Thus, under this approach, the threshold separating the 

Marginal and Moderate classifications for the 2008 ozone NAAQS would be 0.075 ppm plus 15 percent, 

or 0.086 ppm. Table 1, below, depicts this proposed translation for classifications as it would apply for 

the 2008 ozone NAAQS. 

TABLE 1 

SUBPART 2 1-HOUR OZONE DESIGN VALUE CLASSIFICATION TABLE 

TRANSLATION TO 8-HOUR DESIGN VALUES FOR THE 2008 OZONE NAAQS of 0.075 

PPM 

Area class 1-hour design 

value (ppm) 

Percent above 1-hour 

ozone NAAQS 

8-hr ozone design value (ppm) 

Marginal From 0.121 0.833 0.076 

up to1 0.138 15 0.086 

Moderate From 0.138 15 0.086 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 15 of 40 

up to1

 0.160 33.333 0.100 

Serious From 0.160 33.333 0.100 

up to1 0.180 50 0.113 

Severe-15 From 0.180 50 0.113 

up to1 0.190 58.333 0.119 

Severe-17 From 0.190 58.333 0.119 

up to1 0.280 133.333 0.175 

Extreme equal to 

or 

above 

0.280 133.333 0.175 

Note 1: But not including. 

 Based on our analysis of air quality information from 2008-2010, we estimate that approximately 

52 areas had ambient ozone concentrations exceeding the 2008 ozone NAAQS. We use these 52 

“hypothetical nonattainment areas” for purposes of the following discussion.15 These hypothetical areas 

are intended to illustrate the distribution of areas into the proposed classifications. The actual number of 

total nonattainment areas and the classification of each area will depend on decisions made in the 

separate designations process under section 107(d). If we were to use the proposed thresholds in Table 1, 

above, as the basis for classifying nonattainment areas with respect to the 2008 ozone NAAQS, the 52 

hypothetical nonattainment areas based on 2008-2010 air quality data would be distributed in each 

classification as shown in Table 2. 

TABLE 2 

NUMBER OF HYPOTHETICAL NONATTAINMENT AREAS IN EACH CLASSIFICATION 

UNDER THE 2008 OZONE NAAQS: PERCENT-ABOVE-THE-STANDARD METHOD 

Classification 2008 O3 NAAQS (hypothetical areas) 

 

15 Background Information Document: Hypothetical Nonattainment Areas for Purposes of 

Understanding The EPA Proposed Rule for Implementing a 2008 8-Hour Ozone National Ambient Air 

Quality Standard--Illustrative Analysis Based on 2010 Design Values. December 2011. Most 

hypothetical nonattainment areas include multiple counties, based on the existing 1997 8-hour ozone 

nonattainment areas, Combined Statistical Area, or Core Based Statistical Area boundary associated 

with a violating monitor. Note that these areas are used for analytical purposes only. Actual 

nonattainment areas and boundaries will be determined through the designations process. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 16 of 40 

Marginal 43 

Moderate 6 

Serious 3 

Severe 0 

Extreme 0 

Total 52 

The proposed classification method would result in the vast majority of nonattainment areas 

being classified as Marginal. It is possible that a few areas would have a later maximum statutory 

attainment date for their existing classification under the 1997 ozone NAAQS than they would have for 

their new classification under the 2008 NAAQS. For example, an area that would be classified Marginal 

for the more stringent 2008 ozone NAAQS (with an anticipated maximum statutory attainment date in 

2015), may have been classified as Severe for the less-stringent 1997 ozone NAAQS (with a later 

maximum statutory attainment date in 2019).16 This issue did not arise when we promulgated the 

classification structure for the 1997 NAAQS. (See section III.B of this rule for additional details on how 

EPA intends to address previous requests for voluntary bump-ups for the 1997 ozone NAAQS.) 

Many Marginal areas are expected to attain the 2008 NAAQS within 3 years of designation (e.g., 

in 2015) due to reductions of ozone precursors resulting from a number of federal and state emission 

reduction programs that have already been adopted. Such programs include more stringent emission 

standards for onroad and nonroad vehicles and equipment (with associated fleet turnover), regional 

reductions in power plant emissions to address interstate transport,17 and potential future programs such 

as the boiler maximum achievable control technology standards. The EPA estimates that in about half of

the Marginal areas, these reductions in conjunction with other ongoing state and federal controls should 

 

16 As indicated elsewhere in this preamble, the EPA intends to designate areas for the 2008 standard by 

mid-2012. Thus, a 3-year attainment deadline would be in 2015.

17 Federal Implementation Plans: Interstate Transport of Fine Particulate Matter and Ozone and 

Correction of SIP Approvals. August 8, 2011; 76 FR 48208. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 17 of 40 

be sufficient to bring about attainment.18 In other areas, additional control measures may be needed for 

timely attainment. 

 3. Other Classification Methods Considered 

A number of interested parties have recommended to the EPA other options for classification of 

ozone nonattainment areas. The EPA evaluated many other methods but we are not proposing them or 

soliciting comment on them because we did not find them as compelling as the option discussed in this 

proposal. We have included in the docket all written recommendations we have received in recent years 

regarding classification approaches. Other options that we considered but are not proposing are also 

summarized in the docket.19

B. Reclassification of Nonattainment Areas that Have Voluntarily Requested Higher Classifications

The CAA provides three mechanisms for addressing nonattainment areas that may not be able to 

attain by the attainment date provided for their classification. First, section 181(a)(4) provides that 

within 90 days of designation and classification, the Administrator may exercise discretion to reclassify 

an area to a higher (or lower) classification if its DV is within 5 percent of the DV range of the higher 

(or lower) classification.20 Any state interested in taking advantage of this flexibility should submit a 

request to the EPA in sufficient time for the Administrator to make a determination within the 90 days

provided. 

The second mechanism, provided in section 181(b)(2), requires that an area be reclassified to the 

next higher classification (i.e., “bumped-up”) if EPA determines that the area has failed to attain the 

 

18 [Add footnote with EPA’s analysis citation] 

19 Additional Options Considered for Classification of Nonattainment Areas under the Proposed 2008 

Ozone NAAQS. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards. 

Research Triangle Park, NC. December 2011[verify future date]. 

20 This CAA provision also provides the same authority for reclassifying areas to a lower classification, 

an approach that may not be relevant where the area in question is unlikely to attain by the attainment 

date for the classification it receives at the time of designation. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 18 of 40 

standard by the attainment date and does not qualify for the first of two possible 1-year attainment date 

extensions allowed under the CAA (excluding Severe to Extreme reclassification). 

The third mechanism, provided in section 181(b)(3), allows a state to voluntarily request that the 

EPA reclassify the area to a higher classification. The EPA has no discretion to deny such requests. 

Once an area is reclassified to a higher classification, it becomes subject to the associated additional 

planning and control requirements for that higher classification as well and must attain the standard no 

later than the later maximum attainment date for that classification. 

There are seven areas for which states requested a voluntary reclassification with respect to the 

1997 NAAQS. If these areas were classified based on 2008-1010 air quality data and pursuant to the 

classification structure proposed here, it is likely that they would have a lower classification and an 

earlier maximum attainment date for the 2008 NAAQS than such areas have for the 1997 ozone 

NAAQS. EPA has granted voluntary reclassification requests for six of these areas; the request for one

area is still pending.21 These areas are shown in Table 3. 

Table 3 

Areas for which the State Requested a Voluntary Reclassification Under the 1997 NAAQS

Nonattainment Area State 

Original 1997 

NAAQS 

Classification 

Voluntary 

Reclassification 

Potential 

Classification Under 

2008 NAAQS1

Los Angeles-South Coast 

Air Basin CA Severe Extreme Serious 

San Joaquin Valley CA Serious Extreme Serious 

Houston-GalvestonBrazoria TX Moderate Severe Marginal 

Riverside County 

(Coachella Valley) CA Serious Severe Moderate 

Sacramento Metro CA Serious Severe Serious 

 

21 Ventura County, CA was reclassified from Moderate to Serious (Approved 05/20/2008, 73 FR Page 

29073, Effective: 06/19/2008). Houston-Galveston-Brazoria, TX was reclassified from Moderate to 

Severe-15 (Approved 10/01/2008, 73 FR Page 56983, Effective: 10/31/2008). Reclassification of the 

Los Angeles-South Coast, San Joaquin Valley, Riverside County, and Sacramento Metro areas (May 5, 

2010, 75 FR 24409) became effective June 4, 2010. West Mojave Desert, CA requested voluntary 

reclassification from Moderate to Severe-17 that is still pending with the EPA. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 19 of 40 

Ventura County CA Moderate Serious Moderate 

Western Mojave2 CA Moderate Severe Moderate 

Note 1: Based on thresholds proposed in this notice and 2008-2010 design values. 

Note 2: This request for a bump-up is still pending. 

The EPA is proposing that the approved prior voluntary reclassification requests for the 1997 ozone 

NAAQS would also apply for the more stringent 2008 ozone NAAQS unless the state explicitly requests 

otherwise. We believe this is an appropriate mechanism to address the limited situation where an area 

that was voluntarily reclassified for the 1997 ozone NAAQS would have an attainment date for the more 

stringent 2008 ozone NAAQS that is earlier than the area’s attainment date for the less stringent 1997

NAAQS. Based on discussions with states, we also believe it is reasonable to expect that most, if not all, 

of the areas that requested a voluntary reclassification under the less stringent 1997 NAAQS would 

make the same request for the 2008 NAAQS. The EPA is proposing this approach in order to minimize 

burden on states and obviate the need to go through the voluntary reclassification process again. 

C. What are we proposing as the attainment deadlines for nonattainment areas in each classification of

the 2008 ozone NAAQS?

 1. Background

The CAA provides that the primary NAAQS attainment dates for areas subject to subpart 2 must 

be as expeditious as practicable but no later than the deadlines provided in the subpart 2 classification 

table. The deadlines for attainment in the subpart 2 classification table are specified in terms of a certain 

number of years from the date of enactment of the 1990 Amendments to the CAA (i.e., November 15, 

1990). For instance, the attainment date for Moderate areas is expressed as “6 years after November 15, 

1990.” Because these time periods are clearly inappropriate for a new standard promulgated in 2008, we

must interpret the attainment deadlines in the subpart 2 classification table as they would apply to the 

2008 NAAQS. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 20 of 40 

In the Phase 1 rule for implementation of the 1997 ozone NAAQS,22 we interpreted these 

timeframes to run from the date that area designations and nonattainment classifications (by operation of 

law) became effective. We explained in the proposed and final rules for implementation of the 1997 

ozone NAAQS that it was reasonable for these dates to run from the date of designation because other 

provisions of the CAA established the attainment date as a set period of time after designation. See 69 

FR 23966-67; 68 FR 32817. As discussed below, we are proposing this same approach for the 2008 

NAAQS and also proposing an alternate approach where the attainment dates would be at the end of the 

calendar year. We are proposing an alternate approach because we anticipate that designations for the 

2008 NAAQS will be effective some time after the start of the 2012 ozone season23 for most areas and 

possibly well into the summer. As explained in more detail below, the alternative approach would allow

Marginal areas 3 full years to attain, Moderate areas 6 full years to attain, etc. 

 2. Proposal

The EPA is proposing two options for establishing the maximum attainment dates for areas in 

each nonattainment classification. Under the first option, the attainment dates would be the precise 

number of years specified in Table 1 with such time period running from the effective date of 

designation. Under the second option, the attainment dates would be December 31 of the year that is the 

specified number of years in Table 1 after designation. In order to fully evaluate the two options, we

note that the EPA intends to complete initial area designations for the 2008 ozone NAAQS no later than

May 31, 2012. We anticipate the designations will be effective 60 days following publication in the 

Federal Register and that it will take approximately 2 weeks for the designations notice to be published. 

Under this scenario, designations would be effective by approximately mid-August 2012. 

 

22 69 FR 23951 

23 The ozone season for each state is defined in 40 CFR part 58, Appendix D, and, for most areas, runs 

from April to October. See also the July 16, 2009, Proposed Monitoring Rule (74 FR 34525). 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 21 of 40 

For the first option, we are proposing that the deadlines in the subpart 2 classification table 

would be specified in terms of a certain number of years from the effective date of designation for the 

2008 standard. This is the same approach we took for the 1997 NAAQS. In this case, we would interpret 

“year” in the subpart 2 classification table to mean consecutive 365-day periods,24 and we would 

substitute “after the effective date of designation” for the CAA’s “after November 15, 1990” language in 

the subpart 2 classification table. Under this approach the attainment deadline would fall a precise 

number of years after the effective date of designation. As an example, if the Administrator issued 

designations for the 2008 NAAQS on May 31, 2012, and the designations became effective on August 

15, 2012, the attainment dates would run from August 15, 2012, such that a Marginal area would be 

required to attain the 2008 ozone standard by August 15, 2015. 

For the second and the EPA’s preferred option, the attainment date would be specified as a 

certain number of years from the end of the calendar year in which an area’s nonattainment designation

is effective. In other words, if the effective date of designations for the 2008 ozone NAAQS is August 

15, 2012, the 3-year attainment deadline for Marginal areas would be December 31, 2015. 

We are proposing this option as our preferred option for the 2008 ozone NAAQS because, as 

explained above, we believe it is likely that designations will be effective in August 2012, which is late 

in the ozone season. Where the designation is effective late in the ozone season, under the first option a 

Marginal area effectively would have only two ozone seasons following designation to improve its air 

quality in order to attain by its attainment date. This is because compliance with the standard is based on 

air quality during the most recent three full consecutive ozone seasons, and the most recent 3 full ozone 

seasons preceding the attainment deadline in this case would run through the end of the previous year’s 

ozone season. Because attainment is based on three full ozone seasons of air quality data, in order to

attain “by” its attainment date, the area could not consider air quality for an ozone season during which 

 

24 Except in the case of a leap year, where the year would be a rolling 366 day period. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 22 of 40 

the attainment date falls. For example, in the case of the 1997 ozone NAAQS, designations became 

effective on June 15, 2004 and areas had an attainment date of June 15 of the year falling 3, 6, etc. years 

after designation. Thus, in order for a Marginal area to attain by June 15, 2007, it could not consider air 

quality data from the 2007 ozone season, but instead was required to demonstrate attainment based on 

the 3 years of air quality data from 2004-2006. In this situation, the area’s attainment date effectively 

was December 31, 2006. 

Because we anticipate designations will be effective late in the ozone season for the 2008 

NAAQS, we are concerned that if a Marginal area is required to attain in August 2015, the area would 

effectively have only two ozone seasons (the 2013 and 2014 ozone seasons) from the date of designation

to improve its air quality for the purpose of showing attainment. Accordingly, the state would need to

both plan for and achieve all emission reductions necessary for the area to attain by the beginning of the 

2014 ozone season, so that those reductions would be reflected in the air quality data considered for 

determining whether the area attained by its attainment date (i.e., attainment would be based on air 

quality data from 2012-2014). Similarly, a Moderate area would need to implement measures to attain 

by the beginning of the 2017 ozone season in order for those reductions to be reflected in the air quality 

data considered for purposes of determining whether the area attained (data from 2015-2017) by August 

2018. 

 We believe this second option is consistent with the time periods provided for attainment of the 

1-hour ozone NAAQS at the time the CAA was amended. The CAA Amendments were enacted on 

November 15, 1990, after the end of the ozone season for virtually all areas, and for the few areas that 

had year-round ozone seasons, EPA interpreted the Act to allow consideration of air quality in the 

attainment year even though the attainment date fell on November 15. Thus, when the CAA was 

amended in mid-November 1990, 1-hour Marginal areas had three full ozone seasons to achieve any 

reductions necessary for attainment, and Moderate areas had six full ozone seasons, because the 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 23 of 40 

attainment deadline was the anniversary of the enactment of the 1990 CAA (November 15). Thus we 

believe this approach reasonably reflects Congressional intent by providing areas the full period 

specified in Table 1 to achieve reductions necessary for attainment. Table 4 summarizes for each 

proposed option how we would interpret the maximum attainment dates for areas in each classification 

under the 2008 NAAQS, using an example where the effective date of designations is August 15, 2012. 

TABLE 4 

EXAMPLE OF PROPOSED ATTAINMENT DATES FOR THE 2008 STANDARD IF 

NONATTAINMENT DESIGNATIONS ARE EFFECTIVE August 15, 2012

Classification Option 1 Option 2

Marginal August 15, 2015 December 31, 2015 

Moderate August 15, 2018 December 31, 2018 

Serious August 15, 2021 December 31, 2021 

Severe August 15, 2027 or 2029 December 31, 2027 or 2029 

Extreme August 15, 2032 December 31, 2032 

IV. What is the EPA proposing regarding revocation of the 1997 ozone NAAQS at this time? 

At this time, the EPA is proposing to revoke the 1997 ozone NAAQS 1 year after the effective 

date of designations for the 2008 ozone NAAQS for transportation conformity purposes only.25

Revoking the 1997 ozone NAAQS for transportation conformity purposes, as described below, will 

bring certainty to the transportation planning process in ozone nonattainment and maintenance areas. It 

will also ensure that backsliding does not occur for purposes of transportation conformity as areas 

 

25 Transportation conformity is required under CAA section 176(c) to ensure that transportation plans, 

transportation improvement programs (TIPs) and federally supported highway and transit projects are 

consistent with (“conform to”) the purpose of the SIP. Conformity to the purpose of the SIP means that

transportation activities will not cause new air quality violations, worsen existing violations, or delay 

timely attainment of the relevant NAAQS or interim reductions and milestones. The EPA’s 

Transportation Conformity Rule (40 CFR 51.390 and Part 93, subpart A) establishes the criteria and 

procedures for determining whether transportation activities conform to the SIP. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 24 of 40 

designated nonattainment for the 2008 ozone NAAQS will be required to use adequate or approved SIP 

motor vehicle emissions budgets for the 1997 ozone NAAQS or 1-hour ozone NAAQS, if the area has 

such SIP budgets for one of these ozone NAAQS, until SIP budgets are found adequate or are approved 

for the 2008 ozone NAAQS as required by recent court decisions discussed below and as required by 

CAA 176(c)(1).26 Specifically, CAA section 176(c)(1) states, in part, “No metropolitan planning 

organization designated under section 134 of Title 23 shall give its approval to any project, program, or 

plan which does not conform to an implementation plan approved or promulgated under section 7410 of 

this title.” In other words, adequate or approved motor vehicle emissions budgets for a prior NAAQS 

must be used in transportation conformity determinations for a revised NAAQS until such time that 

budgets for the revised NAAQS are either found adequate or are approved. The EPA is proposing this 

limited revocation of the 1997 ozone NAAQS at this time to provide certainty to the transportation 

planning process. In a subsequent rulemaking, the EPA will consider whether to also revoke the 1997 

NAAQS for other purposes. 

A. What is the background for our proposal?

 At the time the EPA promulgated the 2008 NAAQS, the Administrator determined that the 1997 

ozone NAAQS was no longer sufficient to protect public health and the environment with an adequate 

margin of safety and that it was therefore necessary to establish a more stringent standard. 73 FR 16436 

(Mar. 27, 2008). In determining how to transition from the 1997 NAAQS to the more stringent 2008 

NAAQS, the EPA is now presented with the same situation that we faced with the transition from the 1-

hour ozone NAAQS to the more stringent 1997 ozone NAAQS. For that transition, our Phase 1 

 

26 A motor vehicle emissions budget is that portion of the total allowable emissions defined in the 

submitted or approved control strategy implementation plan revision or maintenance plan for a certain 

date for the purpose of meeting reasonable further progress milestones or demonstrating attainment or 

maintenance of the NAAQS, for any criteria pollutant or its precursors, allocated to highway and transit 

vehicle use and emissions. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 25 of 40 

implementation rule for the 1997 ozone NAAQS revoked the 1-hour ozone NAAQS for all purposes 1 

year after the effective date of the initial area designations for the 1997 ozone NAAQS. (See 69 FR 

23954). The Phase 1 rule also established comprehensive anti-backsliding provisions to ensure that 

requirements for the 1-hour ozone NAAQS would continue in place as areas transitioned to 

implementing the more stringent 1997 ozone standard. 

The revocation of the 1-hour standard and the associated anti-backsliding provisions were the 

subject of litigation. In its December 2006 decision on that challenge, as modified following rehearing, 

the Court held with respect to the anti-backsliding approach for transportation conformity, that 1-hour 

motor vehicle emissions budgets must be used where such budgets have been found adequate or 

approved, as part of 8-hour conformity determinations until 8-hour motor vehicle emissions budgets are

available. (South Coast Air Quality Management District v. EPA, XX F.3d at YYY). In addition, the 

Court affirmed more broadly that in order for transportation conformity determinations to fulfill the 

requirements of CAA section 176(c)(1), motor vehicle emissions budgets for a prior NAAQS must be 

used in transportation conformity determinations under a revised NAAQS until emissions budgets for 

the revised NAAQS are either found adequate or are approved. Therefore, areas designated 

nonattainment for the 2008 ozone NAAQS that have adequate or approved SIP budgets for either the 

1997 ozone NAAQS or the 1-hour ozone NAAQS must continue to use such budgets in transportation 

conformity determinations until budgets for the 2008 ozone NAAQS are found adequate or are 

approved.27

 

B. What is the rationale for our proposal?

At this time, we are proposing to revoke the 1997 ozone NAAQS for transportation conformity 

purposes only. The revocation of the 1997 ozone NAAQS for this limited purpose would occur 1 year 

 

27 Areas without adequate or approved SIP budgets for either the 1997 ozone NAAQS or the 1-hour 

ozone NAAQS are required to demonstrate conformity using one or both of the interim emissions tests 

depending on their classification as required by 40 CFR 93.119. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 26 of 40 

after the effective date of initial area designations for the 2008 ozone NAAQS. Similar to our rationale 

in the Phase 1 rule for implementation of the 1997 ozone NAAQS, we believe this approach makes the 

most sense because it would result in only one ozone NAAQS – the 2008 ozone NAAQS – applying for 

purposes of transportation conformity, after the end of the one-year transportation conformity grace 

period that applies to newly designated nonattainment areas. (CAA section 176(c)(6)). If the 1997 ozone 

NAAQS were to remain in place after conformity applies for the 2008 ozone NAAQS, metropolitan 

planning organizations and other state, local, and federal transportation and air quality agencies in areas 

that are currently nonattainment or maintenance for the 1997 ozone NAAQS and will be designated 

nonattainment for the 2008 ozone NAAQS would be required to implement the transportation 

conformity program for both ozone NAAQS concurrently. This could lead to unnecessary complexity 

for conformity determinations, especially if an area’s boundaries for the two ozone NAAQS differ from 

one another and the same test of conformity cannot be used for both ozone NAAQS. Even where an 

area’s boundaries are unchanged, different analysis years under the conformity rules may be required for 

each ozone NAAQS. Furthermore, we believe that it is more important to determine conformity for the 

new 2008 ozone NAAQS that is more protective of health and welfare. 

For transportation conformity purposes, this proposal would provide a seamless transition from 

demonstrating conformity for the 1997 ozone NAAQS to demonstrating conformity for the 2008 ozone 

NAAQS. Revoking the 1997 ozone NAAQS 1 year after the effective date of designations for the 

limited purpose of transportation conformity would leave no gap in conformity’s application in any 2008 

ozone nonattainment areas. 

C. Why is it necessary to revoke the 1997 ozone NAAQS now for transportation conformity purposes?

The EPA has determined that it is necessary to establish the date for the revocation of the 1997 

ozone NAAQS as it applies for transportation conformity purposes now in order to provide state and 

local transportation and air quality agencies with certainty as to what conformity requirements will apply 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 27 of 40 

after designations are finalized for the 2008 ozone NAAQS. Areas designated nonattainment for the 

2008 ozone NAAQS will have 1 year after the effective date of the designation to complete a conformity

determination for the 2008 ozone NAAQS. If an area does not complete the required conformity 

determination by the end of the 1-year grace period, the area will enter a conformity lapse until the 

required determination is completed.28 Based on 2008 – 2010 air quality monitoring data, and as 

discussed elsewhere in today’s notice, we anticipate that 52 areas would be designated as nonattainment 

areas and 44 of these areas are either nonattainment or maintenance for the 1997 ozone NAAQS. Areas 

designated nonattainment for the 2008 NAAQS will likely need the full 1-year grace period provided in 

CAA section 176(c)(6) to complete the required initial conformity determination. Those areas that are

designated as either nonattainment or maintenance for the 1997 ozone NAAQS at the time they are 

designated as nonattainment for the 2008 ozone NAAQS, will need certainty as to the specific 

requirements for that conformity determination. For example they need to know what analysis years 

must be addressed and, if the boundaries for the two ozone NAAQS are different, they need to know 

whether to address conformity for both areas and which test or tests would apply. 

By determining conformity for the 2008 standard, which is the more health and welfare 

protective standard, the EPA is both: 

• Fulfilling the CAA’s requirements for transportation conformity which include preventing new 

air quality violations, not making existing violations worse and not delaying any interim 

milestones; and 

• making the most efficient use of state and local resources in fulfilling those requirements. 

In addition, a large number of areas that are currently required to determine conformity for the 

1997 ozone NAAQS are attaining the 2008 ozone NAAQS based on 2008-2010 air quality data. If these 

 

28 During a lapse, an area can proceed with only a limited amount of transportation projects including 

projects that are exempt from conformity, projects and project phases that had previously been approved 

and transportation control measures included in an approved SIP. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 28 of 40 

areas are designated as attainment areas for the 2008 ozone NAAQS they would not be required to 

demonstrate conformity for either the 1997 ozone NAAQS, as of the effective date of the revocation of 

the 2008 ozone NAAQS. These areas would no longer have to expend resources to make conformity 

determinations for the 1997 ozone NAAQS. 

D. Is the EPA proposing to revoke the 1997 ozone NAAQS for other purposes as part of this 

rulemaking? 

 As part of this rule, the EPA is not proposing to revoke the 1997 ozone NAAQS for purposes 

other than transportation conformity. Because of the necessity to quickly finalize a rule addressing 

nonattainment area classifications, we are not including a broad proposal here regarding revocation of

the 1997 NAAQS and how anti-backsliding requirements might apply if the 1997 standard is revoked 

for purposes other than transportation conformity. We are developing a separate proposed rule that will 

address those issues and we expect to issue that proposed rule in the spring of 2012. We plan to address 

any comments on the issue of revocation and anti-backsliding for all requirements other than 

transportation conformity in the context of that future, separate rulemaking. 

V. What does this rulemaking not address?

 This proposed rulemaking does not propose to establish attainment or nonattainment 

designations for specific areas nor does it address the principles that will be considered in the 

designation process. Because the designations are not the subject of this proposed rule, we do not intend 

to respond to comments concerning designations in the context of this rulemaking. 

In addition, this proposed rule does not address any specific SIP requirements associated with 

different classification categories. This proposed rule also does not address revocation of the 1997 ozone 

NAAQS for purposes other than transportation conformity. Similarly, anti-backsliding issues are not 

addressed in this rule. The remaining implementation requirements for the 2008 NAAQS will be 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 29 of 40 

addressed in a separate rulemaking. We do not intend to respond in the context of this rulemaking to 

comments pertaining to implementation issues that will be addressed by a future rulemaking. 

VI. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving 

Regulation and Regulatory Review 

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is a “significant 

regulatory action” because it raises novel legal or policy issues arising out of legal mandates. 

Accordingly, EPA submitted this action to OMB for review under Executive Orders 12866 and 13563 

(76 FR 3821, January 21, 2011) and any changes made in response to OMB recommendations have been 

documented in the docket for this action. 

B. Paperwork Reduction Act 

 This action does not impose an information collection burden under the provisions of the 

Paperwork Reduction Act, 44 U.S.C. 3501 et seq. Burden is defined at 5 CFR 1320.3(b). 

 The EPA is proposing this Classifications Rule for the 2008 ozone NAAQS so that areas may be 

classified by operation of law at the time of designation as provided in section 181(a) of the CAA. This 

proposed rule would also revoke the 1997 ozone NAAQS for transportation conformity purposes only. 

The EPA is proposing this limited revocation in order to bring certainty to the transportation conformity 

process consistent with prior court decisions and CAA section 176(c). This rule, in conjunction with 

another implementation rule we plan to propose in the future will help states identify planning 

requirements that apply for purposes of attaining and maintaining the 2008 ozone NAAQS. No new 

information needs to be collected from the states as a result of this proposed rule. 

C. Regulatory Flexibility Act

The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a regulatory 

flexibility analysis of any regulation subject to notice and comment rulemaking requirements under the
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 30 of 40 

Administrative Procedures Act or any other statute unless the agency certifies the rule will not have a 

significant economic impact on a substantial number of small entities. Small entities include small 

businesses, small organizations, and small governmental jurisdictions. 

For purposes of assessing the impacts of these proposed regulations on small entities, small 

entity is defined as: (1) a small business as defined in the Small Business Administration’s (SBA) 

regulations at 13 CFR 121.201; (2) a small governmental jurisdiction that is a government of a city, 

county, town, school district or special district with a population of less than 50,000; and (3) a small 

organization that is any not-for-profit enterprise which is independently owned and operated and is not 

dominant in its field. 

The CAA requires the EPA to designate areas and provides for nonattainment areas to be 

classified by operation of law at the time of designation. This rule provides a method for establishing 

these classifications and interpreting the associated attainment deadlines. The CAA also requires that

nonattainment and maintenance areas make transportation conformity determinations. This rule 

proposes to revoke the 1997 ozone NAAQS 1 year after the effective date of designations so that areas 

designated nonattainment for the 2008 ozone NAAQS are required to address conformity requirements 

for only the more protective 2008 ozone NAAQS. 

After considering the economic impacts of this proposed rule on small entities, the EPA certifies 

that this action will not have a significant economic impact on a substantial number of small entities. 

This proposed rule will not impose any requirements on small entities. 

We continue to be interested in the potential impacts of the proposed rule on small entities and 

welcome comments on issues related to such impacts.

D. Unfunded Mandates Reform Act 

This action contains no federal mandate under the provisions of Title II of the Unfunded 

Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 1531-1538 for state, local, and tribal governments, in 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 31 of 40 

the aggregate, or the private sector. This action imposes no enforceable duty on any state, local or tribal 

governments or the private sector. Therefore, this action is not subject to the requirements of section 202 

and 205 of the UMRA. 

This action is not subject to the requirements of section 203 of UMRA because it contains no 

regulatory requirements that might significantly or uniquely affect small governments. 

E. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have substantial direct effects on 

the states, on the relationship between the national government and the states, or on the distribution of 

power and responsibilities among the various levels of government, as specified in Executive Order 

13132. The requirement to designate and classify nonattainment areas is imposed by the CAA as are the 

requirements for nonattainment and maintenance areas to make transportation conformity 

determinations. This proposed rule, if made final, would interpret how the classification provisions in 

section 181(a) will apply for purposes of the 2008 8-hour ozone NAAQS that was finalized on March 

27, 2008. (See 73 FR 16436 ]. It also proposes to revoke the 1997 ozone NAAQS 1 year after the 

effective date of designations for the 2008 ozone NAAQS for transportation conformity purposes only. 

Thus, Executive Order 13132 does not apply to these proposed regulations. 

Although this action does not have federalism implications as defined in Executive Order 13132, 

the EPA recognizes that the adoption in 2008 of the more health-protective ozone standards will result in 

additional effort by state agencies responsible for managing air quality programs. Under the CAA, 

achieving these health benefits requires the combined efforts of the federal, state, and local 

governments, each accomplishing the tasks for which they are best suited. In the spirit of Executive 

Order 13121 and consistent with EPA policy to promote communications between the EPA and state 

and local governments, the EPA is soliciting comments on this proposal from state and local officials. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 32 of 40 

 This action does not have tribal implications, as specified in Executive Order 13175 (65 FR 

67249, November 9, 2000). The proposed rules do not have a substantial direct effect on one or more 

Indian tribes, since no tribe has to develop classification recommendations under these proposed 

regulatory revisions. This proposal revokes the 1997 ozone NAAQS for transportation and does not 

significantly or uniquely affect the communities of Indian tribal governments, as the CAA requires 

transportation conformity to apply in any area that is designated nonattainment or maintenance by the 

EPA. Furthermore, these proposed regulation revisions do not affect the relationship or distribution of 

power and responsibilities between the federal government and Indian tribes. The CAA and the Tribal 

Air Rule establish the relationship of the federal government and tribes in developing plans to attain the 

NAAQS, and these revisions to the regulations do nothing to modify that relationship. These proposed 

regulations revisions do not have tribal implications. Thus, Executive Order 13175 does not apply to this 

action. 

 The EPA specifically solicits additional comment on this proposed action from tribal officials. 

G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks

The EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) as applying only to 

those regulatory actions that concern health or safety risks, such that the analysis required under section 

5-501 of the Executive Order has the potential to influence the regulation. This action is not subject to 

Executive Order 13045 because it does not establish an environmental standard intended to mitigate 

health or safety risks. 

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, 

Distribution, or Use

This action is not a “significant energy action” as defined in Executive Order 13211 (66 FR 

28355 (May 22, 2001)), because it is not likely to have a significant adverse effect on the supply, 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 33 of 40 

distribution, or use of energy. This action would establish classifications for areas that do not attain the 

2008 ozone standard. 

I. National Technology Transfer and Advancement Act

Section 12(d) of the National Technology Transfer Advancement Act of 1995 (NTTAA), Public 

Law No. 104-113, section 12(d) (15 U.S.C. 272 note) directs the EPA to use voluntary consensus 

standards in its regulatory activities unless to do so would be inconsistent with applicable law or 

otherwise impractical. The voluntary consensus standards are technical standards (e.g., materials 

specifications, test methods, sampling procedures, and business practices) that are developed or adopted 

by voluntary consensus standards bodies. NTTAA directs EPA to provide Congress, through OMB, 

explanations when the agency decides not to use available and applicable voluntary consensus standards. 

These proposed revisions to the regulations do not involve technical standards. Therefore, the 

EPA is not considering the use of any voluntary consensus standards. 

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populations 

and Low-Income Populations

Executive Order 12898 (59 FR 7629 (Feb. 16, 1994)) establishes federal executive policy on 

environmental justice. Its main provision directs federal agencies, to the greatest extent practicable and 

permitted by law, to make environmental justice part of their mission by identifying and addressing, as 

appropriate, disproportionately high and adverse human health or environmental effects of their 

programs, policies, and activities on minority populations and low-income populations in the United 

States. 

The EPA has determined that this proposed rule will not have disproportionately high and 

adverse human health or environmental effects on minority or low-income populations because it does 

not affect the level of protection provided to human health or the environment. The proposed regulations 

would, if promulgated, establish classification thresholds for designated nonattainment areas for the 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 34 of 40 

2008 ozone NAAQS, which are designed to protect all segments of the general populations. As such, 

they do not adversely affect the health or safety of minority or low-income populations and are designed 

to protect and enhance the health and safety of these and other populations. Today’s action also proposes 

to revoke the 1997 ozone NAAQS for transportation conformity purposes only. Such a revocation would 

not lead to disproportionately high and adverse human health or environmental effects on minority or 

low-income populations as the CAA requires transportation conformity to apply in any area that is 

designated nonattainment or maintenance by the EPA. This proposed rule ensures that transportation 

conformity is demonstrated in all areas that are designated nonattainment for the more protective 2008

ozone NAAQS. 

K. Determination Under Section 307(d)

Pursuant to sections 307(d)(1)(E) and 307(d)(1)(V) of the CAA, the Administrator proposes to 

determine that this action is subject to the provisions of section 307(d). Section 307(d)(1)(V) provides 

that the provisions of section 307(d) apply to “such other actions as the Administrator may determine.” 

VII. Statutory Authority 

The statutory authority for this action is provided by sections 110; 176; 181; and 301(a)(1) of the 

CAA, as amended (42 U.S.C. 7409; 42 U.S.C. 7506; 42 U.S.C. 7511; 42 U.S.C. 7601(a)(1)). This notice 

is also subject to section 307(d) of the CAA (42 U.S.C. 7407(d)). 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 35 of 40 

Page 35 of 40- Implementation of the 2008 National Ambient Air Quality Standards for Ozone: 

Nonattainment Area Classifications Approach, Attainment Deadlines and Revocation of the 1997 

Ozone Standards for Transportation Conformity Purposes 

LIST OF SUBJECTS 

40 CFR Part 50

 Environmental protection, Air pollution control, Carbon monoxide, Lead, Nitrogen dioxide, 

Ozone, Particulate matter, Sulfur oxides. 

40 CFR Part 51

 Air pollution control, Intergovernmental relations, Ozone, Particulate matter, Transportation, 

Volatile organic compounds. 

________________________________ 

Dated: 

________________________________ 

Lisa P. Jackson, 

Administrator. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 36 of 40 

For the reasons stated in the preamble, Title 40, Chapter I of the Code of Federal Regulations is 

proposed to be amended as follows: 

Part 50–National Primary and Secondary Ambient 

Air Quality Standards

1. The authority citation for Part 50 continues to read as follows: 

Authority: 42 U.S.C. 7401, et seq. 

2. Section 50.10 is amended by adding a paragraph (c) to read as follows: 

§50.10 National 8-hour primary and secondary ambient air quality standards for ozone. 

(c) The 1997 ozone NAAQS set forth in paragraph (a) of this section will no longer apply to an area for 

transportation conformity purposes 1 year after the effective date of the designation of the area for the 

2008 ozone NAAQS pursuant to section 107 of the CAA. The 1997 ozone NAAQS set forth in this 

section will continue to remain applicable to all areas for all other purposes notwithstanding the 

promulgation of the 2008 ozone NAAQS under §50.15 or the designation of areas for the 2008 ozone 

NAAQS. Area designations and classifications with respect to the 1997 ozone NAAQS are codified in 

40 CFR part 81. 

Part 51–Requirements for Preparation, Adoption, and Submittal of Implementation Plans

3. The authority citation for Part 51 continues to read as follows: 

Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q. 

* * * * * 

4. Part 51 is amended by adding a new subpart AA to read as follows: 

Subpart AA–Provisions for Implementation of the 2008 Ozone National Ambient Air Quality 

Standards
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 37 of 40 

Sec. 

51.1100 Definitions. 

51.1101 Applicability of Part 51. 

51.1102 Classification and nonattainment area planning provisions. 

51.1103 Application of classification and attainment date provisions in section 181 of subpart 2 of the 

CAA to areas subject to §51.1102(a). 

Subpart AA–Provisions for Implementation of the 2008 Ozone National Ambient Air Quality 

Standards.

§51.1100 Definitions.

The following definitions apply for purposes of this subpart. Any term not defined herein shall have the 

meaning as defined in 40 CFR 51.100. 

(a) 1-hour NAAQS means the 1-hour primary and secondary ozone national ambient air quality 

standards codified at 40 CFR 50.9. 

(b) 1997 NAAQS means the 8-hour primary and secondary ozone national ambient air quality standards 

codified at 40 CFR 50.10. 

 (c) 2008 NAAQS means the 2008 primary and secondary ozone NAAQS codified at 40 CFR 50.15. 

(d) 1-hour ozone design value is the 1-hour ozone concentration calculated according to 40 CFR part 

50, Appendix H and the interpretation methodology issued by the Administrator most recently before 

the date of the enactment of the CAA Amendments of 1990. 

(e) 8-hour ozone design value is the 8-hour ozone concentration calculated according to 40 CFR part 50, 

Appendix P. 

(f) CAA means the Clean Air Act as codified at 42 U.S.C. 7401 - 7671q (2010). 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 38 of 40 

(g) Attainment area means, unless otherwise indicated, an area designated as either attainment, 

unclassifiable, or attainment/unclassifiable. 

(h) Attainment year ozone season shall mean the ozone season immediately preceding a nonattainment 

area’s maximum attainment date. 

 (i) Designation for the 2008 NAAQS shall mean the effective date of the designation for an area for the 

2008 NAAQS. 

(j) Higher classification/lower classification. For purposes of determining whether a classification is 

higher or lower, classifications under subpart 2 are ranked from lowest to highest as follows: Marginal; 

Moderate; Serious; Severe; and Extreme. 

(k) Initially designated means the first designation that becomes effective for an area for the 2008 

NAAQS and does not include a redesignation to attainment or nonattainment for the 2008 NAAQS. 

(l) Maintenance area means an area that was designated nonattainment for a specific NAAQS and was 

redesignated to attainment for that NAAQS subject to a maintenance plan as required by CAA section 

175A. 

(m) Nitrogen Oxides (NOx) means the sum of nitric oxide and nitrogen dioxide in the flue gas or 

emission point, collectively expressed as nitrogen dioxide. 

(n) Ozone season means for each state, the ozone monitoring season as defined in 40 CFR Part 58, 

Appendix D, section 2.5 for that state. 

§51.1101 Applicability of Part 51. 

The provisions in subparts A-X of part 51 apply to areas for purposes of the 2008 NAAQS to the extent 

they are not inconsistent with the provisions of this subpart. 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

Page 39 of 40 

§51.1102 Classification. 

An area designated nonattainment for the 2008 NAAQS will be classified in accordance with CAA 

section 181, as interpreted in §51.1103(a), and will be subject to the requirements of subpart 2 that apply 

for that classification. 

§51.1103 Application of classification and attainment date provisions in CAA section 181 of 

subpart 2 to areas subject to §51.1102. 

(a) In accordance with CAA section 181(a)(1), each area designated nonattainment for the 2008 ozone 

NAAQS shall be classified by operation of law at the time of designation. The classification shall be

based on the 8-hour design value for the area at the time of designation, in accordance with Table 1 

below. A state may request a higher or lower classification as provided in paragraphs (b) and (c) of this 

section. For each area classified under this section, the attainment date for the 2008 NAAQS shall be as 

expeditious as practicable but not later than the date provided in Table 1 as follows: 
*** E.O. 12866 review – Draft – Do Not Cite, Quote, or Release During Review *** 

EO12866_NA Classifications Approach_2060-AP24_NPRM_FRN_20111123 

40 

TABLE 1 

CLASSIFICATION FOR 2008 8-HOUR OZONE NAAQS (0.075 ppm) 

FOR AREAS SUBJECT TO SECTION 51.1102(a)

Area class 8-hour design value 

(ppm ozone) 

Primary Standard Attainment Date

(years after designation for 2008 

primary NAAQS)**

Marginal from 0.076 3 

up to* 0.086 

Moderate from 0.086 6 

up to* 0.100 

Serious from 0.100 9 

up to* 0.113 

Severe-15 from 0.113 15 

up to* 0.119 

Severe-17 from 0.119 17 

up to* 0.175 

Extreme equal to or 

above 0.175 

20 

* but not including 

** The attainment date is [Option 1: the date that is the specified number of years after 

the effective date of designations for the primary NAAQS.Option 2: December 31 of the 

calendar year] 

(b) A state may request, and the Administrator must approve, a higher classification for any 

reason in accordance with CAA section 181(b)(3). 

(c) A state may request, and the Administrator may in the Administrator’s discretion approve, a 

higher or lower classification in accordance with CAA section 181(a)(4). 

(d) Any area designated nonattainment that includes in whole or in part the following areas will 

be classified by operation of law for the 2008 ozone NAAQS in accordance with the voluntary 

classification request submitted for each area for the 1997 ozone NAAQS, unless the state 

submits a letter to EPA requesting otherwise: Ventura Co, CA; Houston-Galveston-Brazoria, 

TX; Los Angeles-South Coast, CA; San Joaquin Valley, CA; Riverside County, CA; and 

Sacramento Metro, CA.