The EPA Regional Administrator, Jared Blumenfeld signed the following 

proposed rule on March 14, 2013 and EPA is submitting it for publication in 

the Federal Register (FR). While we have taken steps to ensure the accuracy 

of this Internet version of the proposed rule, it is not the official version 

of the proposal for purposes of public comment. Please refer to the official 

version in a forthcoming FR publication appearing on the Government Printing 

Office’s FDsys website, http://fdsys.gpo.gov/fdsys/search/home.action and on 

Regulation.gov in Docket Number EPA-R09-OAR-2012-0971, 

http://www.regulations.gov.

Billing Code: 6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2012-0971;_________]

Approval and Promulgation of Implementation Plans and 

Designation of Areas for Air Quality Planning Purposes; State of 

California; Redesignation of San Diego County to Attainment for 

the 1997 8-Hour Ozone Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: EPA is proposing to approve, as a revision of the 

California state implementation plan, a request from the 

California Air Resources Board to redesignate the San Diego 

County ozone nonattainment area to attainment of the 1997 8-hour 

ozone National Ambient Air Quality Standard (1997 ozone 

standard) because the request meets the statutory requirements 

for redesignation under the Clean Air Act. EPA is also proposing 

to approve the State's plan for maintaining the 1997 ozone 

standard in San Diego County for ten years beyond redesignation, 

and the inventories and related motor vehicle emissions budgets
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

2

within the plan, because they meet the applicable requirements 

for such plans and budgets. 

DATES: Comments must be received on or before [Federal Register: 

Insert date 30 days after the publication date].

ADDRESSES: Submit your comments, identified by Docket ID Number 

EPA-R09-OAR-2012-0971, by one of the following methods:

1. http://www.regulations.gov: Follow the on-line 

instructions for submitting comments.

2. Email: r9_airplanning@epa.gov.

3. Fax: 415-947-3579

4. Mail or deliver: John Ungvarsky (AIR-2), U.S. 

Environmental Protection Agency, Region IX, 75 Hawthorne Street, 

San Francisco, CA 94105-3901. Deliveries are only accepted 

during the Regional Office's normal hours of operation.

Instructions: All comments will be included in the public 

docket without change and may be made available online at 

http://www.regulations.gov, including any personal information 

provided, unless the comment includes Confidential Business 

Information (CBI) or other information whose disclosure is 

restricted by statute. Information that you consider CBI or 

otherwise protected should be clearly identified as such and 

should not be submitted through http://www.regulations.gov or 

email. http://www.regulations.gov is an anonymous access system, 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

3

and EPA will not know your identity or contact information 

unless you provide it in the body of your comment. If you send 

email directly to EPA, your email address will be automatically 

captured and included as part of the public comment. If EPA 

cannot read your comment due to technical difficulties and 

cannot contact you for clarification, EPA may not be able to 

consider your comment.

Docket: Generally, documents in the docket for this action 

are available electronically at www.regulations.gov and in hard 

copy at EPA Region IX, 75 Hawthorne Street, San Francisco, 

California. While all documents in the docket are listed at 

www.regulations.gov, some information may be publicly available 

only at the hard copy location (e.g., copyrighted material, 

large maps), and some may not be publicly available in either 

location (e.g., CBI). To inspect the hard copy materials, please 

schedule an appointment during normal business hours with the 

contact listed in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: John Ungvarsky, Air Planning 

Office (AIR-2), U.S. Environmental Protection Agency, Region IX, 

(415) 972-3963, ungvarsky.john@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, whenever 

“we,” “us,” or “our” is used, we mean EPA. This supplementary 

information section is arranged as follows:
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

4

Table of Contents

I. Summary of Today's Proposed Action

II. Background

III. Procedural Requirements for Adoption and Submittal of SIP 

Revisions

IV. Substantive Requirements for Redesignation

V. Evaluation of the State's Redesignation Request for the San 

Diego County 8-Hour Ozone Nonattainment Area 

A. Determination That the Area Has Attained the Applicable 

NAAQS.

B. The Area Must Have a Fully Approved SIP Meeting 

Requirements Applicable for Purposes of Redesignation under 

Section 110 and Part D.

1. Basic SIP Requirements under CAA Section 110

2. Part D Requirements

a. Introduction

b. Subpart 1 Requirements

c. Subpart 2 Requirements

C. The Area Must Show the Improvement in Air Quality is Due to 

Permanent and Enforceable Emissions Reductions.

D. The Area Must Have a Fully Approved Maintenance Plan under 

CAA Section 175A.

1. Attainment Inventory
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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2. Maintenance Demonstration

3. Monitoring Network

4. Verification of Continued Attainment

5. Contingency Provisions

6. Subsequent Maintenance Plan Revisions

7. Motor Vehicle Emissions Budgets

VI. Proposed Action and Request for Public Comment

VII. Statutory and Executive Order Reviews

I. Summary of Today's Proposed Action

EPA is proposing to take several related actions. First, 

under Clean Air Act (CAA or "Act") section 110(k)(3), EPA is 

proposing to approve a maintenance plan for the 1997 8-hour 

ozone standard (“San Diego 8-hour maintenance plan”) for the San 

Diego County 1997 ozone nonattainment area (“San Diego 8-hour 

area”) as a revision to the California state implementation plan 

(SIP).1 The San Diego 8-hour maintenance plan is included in a 

document titled Redesignation Request and Maintenance Plan for 

the 1997 National Ozone Standard for San Diego County (December 

2012) submitted by the California Air Resources Board (CARB) on 

December 28, 2012.

 

1 On March 27, 2008 (73 FR 16436), EPA promulgated a revised 8-hour ozone 

standard of 0.075 ppm (the 2008 8-hour ozone standard), and on May 21, 2012, 

EPA designated San Diego County as nonattainment for the 2008 8-hour ozone 

standard (77 FR 30088). This rulemaking relates only to the 1997 8-hour ozone 

standard and does not relate to the 2008 8-hour ozone standard.
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In connection with the San Diego 8-hour maintenance plan, 

EPA finds that the maintenance demonstration showing how the 

area will continue to attain the 1997 8-hour ozone national 

ambient air quality standard (1997 ozone NAAQS or 1997 ozone 

standard) for at least 10 years beyond redesignation (i.e., 

through 2025) and the contingency provisions describing the 

actions that the San Diego County Air Pollution Control District 

(SDAPCD) will take in the event of a future monitored violation 

meet all applicable requirements for maintenance plans and 

related contingency provisions in CAA section 175A. EPA is also 

proposing to approve the motor vehicle emissions budgets (MVEBs) 

in the San Diego 8-hour maintenance plan because we find they 

meet the applicable transportation conformity requirements under 

40 CFR 93.118(e).

Second, under CAA section 107(d)(3)(D), EPA is proposing to 

approve CARB’s request that accompanied the submittal of the San 

Diego 8-hour maintenance plan, that is, to redesignate the San 

Diego 8-hour area to attainment for the 1997 ozone standard. We 

are doing so based on our conclusion that the area has met the 

five criteria for redesignation under CAA section 107(d)(3)(E). 

Our conclusion in this regard is in turn based on our proposed 

determination that the area has attained the 1997 ozone 

standard, that relevant portions of the California SIP are fully 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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approved, that the improvement in air quality is due to 

permanent and enforceable reductions in emissions, that 

California has met all requirements applicable to the San Diego 

8-hour area with respect to section 110 and part D of the CAA, 

and based on our proposed approval as part of this action of the 

San Diego 8-hour maintenance plan.

II. Background

Ground-level ozone is generally not emitted directly by 

sources. Rather, directly-emitted oxides of nitrogen (NOX) and 

volatile organic compounds (VOC) react in the presence of 

sunlight to form ground-level ozone, as a secondary pollutant, 

along with other secondary compounds. NOX and VOC are “ozone 

precursors.” Reduction of peak ground-level ozone concentrations 

is typically achieved through controlling VOC and NOX emissions.

In 1971, under section 109 of the Act, as amended in 1970, 

EPA promulgated the original NAAQS for several pervasive air 

pollutants, including photochemical oxidants. NAAQS represent 

concentration levels the attainment and maintenance of which, 

allowing for an adequate margin of safety, EPA has determined to 

be requisite to protect public health ("primary" NAAQS) and 

welfare ("secondary" NAAQS). 

In 1978, EPA designated the San Diego Air Basin as a 

nonattainment area (SDAB nonattainment area) for the 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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photochemical oxidant NAAQS. See 43 FR 8962 (March 3, 1978). In 

1979, EPA revised the NAAQS from an hourly average of 0.08 parts 

per million (ppm) oxidant to an hourly average of 0.12 ppm ozone

(1979 ozone standard). See 44 FR 8202 (February 8, 1979). The 

nonattainment designation for the SDAB nonattainment area for 

photochemical oxidants carried over to the 1979 ozone standard

(SDAB 1-hour area). 

During the 1980s, SDAPCD adopted a number of rules and 

prepared a number of nonattainment plans to address planning 

requirements under the CAA, as amended in 1977. CARB submitted 

these rules and plans to EPA at various times, and EPA approved 

a number of them into the California SIP. Among the rules 

approved by EPA as revisions to the California SIP as part of 

the ozone control strategy in San Diego County are SDAPCD Rules: 

67.0 Architectural Coatings; 67.6.2 Vapor Degreasing Operations;

and 69.2 Industrial and Commercial Boilers, Process Heaters and 

Steam Generators.

In 1997, EPA revised the NAAQS for ozone, setting it at 

0.08 ppm averaged over an 8-hour time frame (1997 ozone NAAQS or 

1997 ozone standard). EPA set the 1997 ozone standard based on 

scientific evidence demonstrating that ozone causes adverse 

health effects at lower ozone concentrations and over longer 

periods of time, than was understood when the pre-existing 1-
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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hour ozone standard was set. EPA determined that the 1997 ozone 

standard would be more protective of human health, especially 

for children and adults who are active outdoors, and individuals 

with a pre-existing respiratory disease, such as asthma.

In 2002, in light of monitored levels below the 1979 ozone 

standard, EPA determined that the SDAB 1-hour nonattainment area 

attained the 1979 ozone standard. See 67 FR 54580 (August 23, 

2002). In 2003, EPA redesignated the San Diego area to 

attainment for the 1979 ozone standard. See 68 FR 37976 (June 

26, 2003).

In 2004, EPA designated areas of the country with respect 

to the 1997 ozone standard. See 69 FR 23857 (April 30, 2004).

Under EPA's "Phase 1" implementation rule for the 1997 ozone 

standard (69 FR 23951, April 30, 2004), a nonattainment area was 

classified under subpart 2 based on its 8-hour ozone design 

value (i.e., the 3-year average annual fourth-highest daily 

maximum 8-hour average ozone concentration at the worst-case 

monitoring site in the area), if it had a 1979 1-hour ozone 

standard design value2 at the time of designation at or above 

0.121 ppm. All other areas were to be implemented under subpart 

 

2 The design value for the 1979 1-hour ozone standard is the fourth-highest 

daily maximum 1-hour ozone concentration over a three-year period at the 

worst-case monitoring site in the area.
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1 based on their 1997 8-hour ozone standard design values3 (69 FR 

23958). San Diego County was designated as a "subpart 1" ozone 

nonattainment area (San Diego 8-hour area) by EPA on April 30, 

2004 based on air quality monitoring data from 2001-2003,

4 (69 FR 

23887, April 30, 2004). The designation became effective on June 

15, 2004.

On December 22, 2006, the U.S. Court of Appeals for the 

District of Columbia Circuit (D.C. Circuit) vacated EPA's Phase 

1 implementation rule for the 1997 ozone standard (69 FR 23951, 

April 30, 2004). South Coast Air Quality Management Dist. v. 

EPA, 472 F.3d 882 (D.C. Cir. 2006). On June 8, 2007, in response 

to several petitions for rehearing, the D.C. Circuit Court 

(Court) clarified that the Phase 1 rule was vacated only for 

those parts of the rule that had been successfully challenged. 

The June 8, 2007 clarification left intact the Court's vacature 

of portions of EPA's Phase 1 rule that related to implementing 

 

3 The design value for the 1997 8-hour ozone standard is the three-year 

average of the annual fourth-highest daily maximum 8-hour ozone concentration 

at the worst-case monitoring site in the area.

4 That portion of San Diego County that excludes the areas listed below: 

La Posta Areas #1 and #2; Cuyapaipe Area; Manzanita Area; and Campo Areas #1 

and #2. The boundaries for these designated areas are based on coordinates of 

latitude and longitude derived from EPA Region 9's GIS database and are 

illustrated in a map entitled "Eastern San Diego County Attainment Areas for 

the 8-Hour Ozone NAAQS," dated March 9, 2004, including an attached set of 

coordinates. The map and attached set of coordinates are available at EPA's 

Region 9 Air Division office. The designated areas roughly approximate the 

boundaries of the reservations for these tribes, but their inclusion is 

intended for CAA planning purposes only and is not intended to be a federal 

determination of the exact boundaries of the reservations. Also, the specific 

listing of these tribes does not confer, deny, or withdraw Federal 

recognition of any of the tribes so listed nor any of the tribes not listed.
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ensure the accuracy of this version, but it is not the official version.

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the 1997 ozone standard in certain nonattainment areas under 

subpart 1 in lieu of subpart 2 of Title 1 Part D of the CAA. 

On June 15, 2007, CARB submitted the Eight-Hour Ozone 

Attainment Plan for San Diego County (May 2007) (“2007 8-hour 

attainment plan”) to EPA as a revision to the California SIP. 

The 2007 8-hour attainment plan included Motor Vehicle Emissions 

Budgets (MVEBs) of 53 and 98 tons per day (ozone season) for VOC 

and NOx, respectively, for 2008. On May 23, 2008, EPA found the 

MVEBs in the 2007 8-hour attainment plan adequate for the 

purposes of transportation conformity. See 73 FR 30098 (May 23, 

2008). Since the effective date of EPA's adequacy finding (i.e., 

June 9, 2008), the applicable metropolitan planning organization 

(MPO), i.e., San Diego Association of Governments, and the U.S. 

Department of Transportation, have been required to use these 

budgets in transportation conformity analyses for regional 

transportation plans, programs projects and amendments. 

On May 14, 2012, in response to the Court’s vacature of the 

provisions of the Phase 1 rule that allowed for implementation 

of the 1997 ozone standard for certain nonattainment areas, 

including San Diego County, solely under subpart 1, EPA 

classified the San Diego 8-hour area as a moderate nonattainment 

area for the 1997 ozone standard under subpart 2 of the CAA (77 

FR 28424).
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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In a letter dated November 26, 2012, CARB requested 

parallel processing of the San Diego 8-hour maintenance plan, 

which was scheduled for adoption by the SDAPCD on December 5, 

2012.

5 On December 28, 2012, CARB submitted the San Diego 8-hour 

maintenance plan and requested that EPA redesignate the San 

Diego 8-hour area to attainment for the 1997 ozone standard. We 

are proposing action today on CARB’s December 28, 2012 

redesignation request and submittal of the San Diego 8-hour 

maintenance plan.

III. Procedural Requirements for Adoption and Submittal of SIP 

Revisions

Section 110(l) of the Act requires States to provide 

reasonable notice and public hearing prior to adoption of SIP 

revisions. In this action, we are proposing action on CARB’s 

December 28, 2012 submittal of the San Diego 8-hour maintenance 

plan as a revision to the California SIP. 

Documents in CARB’s submittal describe the public review 

process followed by SDAPCD in adopting the plan prior to 

transmittal to CARB for subsequent submittal to EPA as a 

revision to the California SIP. The documentation provides 

evidence that reasonable notice of a public hearing was provided 

 

5

 On November 26, 2012, James Goldstene, Executive Officer of CARB, submitted 

a request to Jared Blumenfeld, Regional Administrator, U.S. EPA Region IX,

for parallel processing of the Redesignation Request and Maintenance Plan for 

the 1997 National Ozone Standard for San Diego County, for which CARB had 

scheduled for Board action at a December 6, 2012 public hearing.
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to the public and that a public hearing was conducted prior to 

adoption. 

On November 2, 2012, SDAPCD published in the San Diego 

Commerce, a newspaper of general circulation within the San 

Diego area, an announcement that a public hearing would be held 

on December 5, 2012 to consider and approve the San Diego 8-hour 

maintenance plan. Copies of the plan were made available for 

viewing at SDAPCD’s offices and on their Web site.

6 On December 

5, 2012, the Air Pollution Control Board of San Diego County 

adopted the San Diego 8-hour maintenance plan at the publicly 

noticed public hearing. Following adoption, SDAPCD forwarded the 

plan to CARB, the Governor of California's designee for SIP 

matters, and CARB then submitted the plan on December 28, 2012 

as a revision to the California SIP to EPA for approval.

Based on the documentation provided by ARB, we find that 

the submittal of the San Diego 8-hour maintenance plan as a SIP 

revision satisfies the procedural requirements of section 110(l) 

of the Act for revising SIPs. 

IV. Substantive Requirements for Redesignation

The CAA establishes the requirements for redesignation of a 

nonattainment area to attainment. Specifically, section 

 

6 The redesignation request and maintenance plan, titled “Redesignation 

Request and Maintenance Plan for the 1997 National Ozone Standard for San 

Diego County,” may be found at the following SDAPCD Web address: 

http://www.sdapcd.org/planning/8_Hour_O3_Maint-Plan.pdf
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ensure the accuracy of this version, but it is not the official version.

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107(d)(3)(E) allows for redesignation provided that the 

following criteria are met: (1) EPA determines that the area has 

attained the applicable NAAQS; (2) EPA has fully approved the 

applicable implementation plan for the area under section 

110(k); (3) EPA determines that the improvement in air quality 

is due to permanent and enforceable reductions in emissions 

resulting from implementation of the applicable SIP, applicable 

federal air pollution control regulations, and other permanent 

and enforceable reductions; (4) EPA has fully approved a 

maintenance plan for the area as meeting the requirements of CAA 

section 175A; and (5) the State containing such area has met all 

requirements applicable to the area under section 110 and part D 

of the CAA. Section 110 identifies a comprehensive list of 

elements that SIPs must include, and part D establishes the SIP 

requirements for nonattainment areas. Part D is divided into six 

subparts. The generally-applicable nonattainment SIP 

requirements are found in part D, subpart 1, and the ozonespecific nonattainment SIP requirements are found in part D, 

subpart 2.

EPA provided guidance on redesignations in a document 

entitled, “State Implementation Plans; General Preamble for the 

Implementation of Title I of the Clean Air Act Amendments of 

1990,” published in the Federal Register on April 16, 1992 (57 
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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FR 13498), and supplemented on April 28, 1992 (57 FR 18070) 

(referred to herein as the “General Preamble”). Another relevant 

EPA guidance document includes “Procedures for Processing 

Requests to Redesignate Areas to Attainment,” Memorandum from 

John Calcagni, Director, Air Quality Management Division, EPA 

Office of Air Quality Planning and Standards, September 4, 1992 

(referred to herein as the “Calcagni memo”).

For the reasons set forth below in section V of this 

document, we propose to approve CARB's request for redesignation 

of the San Diego County 8-hour ozone nonattainment area to 

attainment for the 1997 8-hour ozone NAAQS based on our 

conclusion that all of the criteria under CAA section 

107(d)(3)(E) have been satisfied. 

V. Evaluation of the State's Redesignation Request for the San 

Diego County 8-Hour Ozone Nonattainment Area

A. Determination That the Area Has Attained the Applicable 

NAAQS.

CAA section 107(d)(3)(E)(i) requires that we determine that 

the area has attained the NAAQS. EPA generally makes the 

determination of whether an area’s air quality meets the ozone 

NAAQS based upon the most recent three years of complete, 

quality-assured data gathered at established State and Local Air 

Monitoring Stations (SLAMS) in the nonattainment area and 
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ensure the accuracy of this version, but it is not the official version.

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entered into the EPA Air Quality System (AQS) database. Data 

from air monitors operated by state/local agencies in compliance 

with EPA monitoring requirements must be submitted to AQS. Heads 

of monitoring agencies annually certify that these data are 

accurate to the best of their knowledge. Accordingly, EPA relies 

primarily on data in AQS when determining the attainment status 

of areas. See 40 CFR 50.10; 40 CFR part 50, appendix I; 40 CFR 

part 53; 40 CFR part 58, appendices A, C, D and E. All data are 

reviewed to determine the area's air quality status in 

accordance with 40 CFR part 50, appendix I.

Under EPA regulations at 40 CFR part 50, the 1997 ozone 

standard is met at an ambient air quality monitoring site when 

the 3-year average of the annual fourth-highest daily maximum 8-

hour average ozone concentration is less than or equal to 0.08 

ppm. See 40 CFR 50.10; 40 CFR part 50, appendix I. This 3-year 

average is referred to as the design value. When the design 

value is less than or equal to 0.084 ppm (based on the rounding 

convention in 40 CFR part 50, appendix I) at each monitoring 

site within the area, then the area is meeting the NAAQS. The 

data completeness requirement is met when the three-year average 

percent of days with valid ambient monitoring data is at least 

90% of the days during the designated ozone monitoring season, 
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and no single year has less than 75% data completeness as 

determined in appendix I of 40 CFR part 50.

The SDAPCD is responsible for monitoring ambient air 

quality within San Diego County. SDAPCD submits monitoring 

network plan reports to EPA on an annual basis. These reports 

discuss the status of the air monitoring network, as required 

under 40 CFR part 58. Beginning in 2007, EPA has reviewed these 

annual plans for compliance with the applicable reporting 

requirements in 40 CFR 58.10. With respect to ozone, we have 

found SDAPCD's annual network plans to meet the applicable 

requirements under 40 CFR part 58. See EPA letters to SDAPCD

concerning SDAPCD's annual network plan reports for 2010, 2011, 

and 2012 included in the docket for this rulemaking. 

Furthermore, we concluded in our Technical System Audit Report 

(System Audit of the Ambient Monitoring Program: San Diego 

County Air Pollution Control District, September 28 – September 

30, 2010, April 2012) that SDAPCD's ambient air monitoring 

network currently meets or exceeds the requirements for the 

minimum number of monitoring sites designated as SLAMS for all 

of the criteria pollutants. Whereas EPA regulations require two 

ozone monitoring sites in this region, SDAPCD operated ten ozone 

monitors during the 2009-2011 attainment period, substantially 

exceeding the requirement. Also, SDAPCD annually certifies that 
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the data it submits to AQS are complete and quality-assured. 

See, e.g., Letter dated March 2, 2012, from Mahmood Hoosain, 

Chief of the Monitoring & Technical Services Division, SDAPCD, 

to Matthew Lakin, Chief Air Quality Analysis Office, EPA Region 

IX.

SDAPCD operated ten ozone SLAMS monitoring sites during the 

2009-2011 period7 within the San Diego County ozone nonattainment 

area: Alpine, Camp Pendleton, Chula Vista, Del Mar, Downtown, El 

Cajon, Escondido, Kearney Mesa, Kearny Villa8 and Otay Mesa. All 

ten sites have monitored ozone concentrations on a continuous 

basis using ultraviolet absorption monitors. The spatial scale 

of most of SDAPCD's ozone monitoring sites are “neighborhood” 

and the site types (i.e., monitoring purpose) are “background 

level” or “representative concentration”. The exceptions are the 

Otay Mesa site, whose spatial scale is “micro” and site type is 

“source impact,” and the Alpine site, whose spatial scale is 

“neighborhood” and site type is “highest concentration.” See 

2011 Ambient Air Quality Network Plan Report, San Diego County 

Air Pollution Control District.9,10

 

7 San Diego County’s monitoring network exceeded the number of required 

monitors throughout the referenced time period.

8 The Kearney Villa site was not operational for the entire 2009-2011 time 

frame. It was established in 2010 to replace Kearny Mesa, which closed in 

February 2012.

9 2011 Ambient Air Quality Network Plan Report, SDAPCD, June 30, 2012, is 

available at http://www.sdapcd.org/air/reports/2011_network_plan.pdf.

10 In the network plan “site type” is referred to as “monitoring objective”.
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Consistent with the requirements contained in 40 CFR part

50, EPA has reviewed the ozone ambient air monitoring data for 

the monitoring period from 2009 through 2011 collected at the 

monitoring sites discussed above, as recorded in AQS and 

summarized in table 1, and found that the data meet our 

completeness criteria. 

Table 1 summarizes the site-specific annual fourth-highest

daily maximum 8-hour ozone concentrations and 3-year ozone 

design values for all monitoring sites within the San Diego 

County 8-hour ozone nonattainment area for the period of 2009-

2011. As shown in table 1, the design value for the 2009-2011 

period was less than 0.084 ppm at all of the monitors. 

Therefore, we are proposing to determine, based on the complete, 

quality-assured data for 2009-2011, that the San Diego County 8-

hour ozone nonattainment area has attained the 1997 8-hour ozone 

standard. Because the Kearny Mesa monitoring site closed in 

February 2012, there are nine ozone monitors currently operating 

in the nonattainment area. Preliminary SLAMS data for 2012 from 

these monitors, which are summarized in table 2, are also 

consistent with continued attainment.

Table 1: Summary of Ambient Data for Ozone Collected within San 

Diego County 8-Hour Ozone Nonattainment Area, 2009-2011.

4

th Highest Value (ppm)
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Monitor Site Code

2009 2010 2011

2009-2011 

Design 

Value

Alpine 06-073-1006 0.085 0.081 0.082 0.082

Camp 

Pendleton

06-073-1008 0.071 0.064 0.067 0.067

Chula Vista 06-073-0001 0.067 0.068 0.055 0.063

Del Mar 06-073-1001 0.067 0.063 0.064 0.064

Downtown 06-073-1010 0.060 0.058 0.060 0.059

El Cajon 06-073-0003 0.071 0.073 0.070 0.071

Escondido 06-073-1002 0.074 0.075 0.068 0.072

Kearny Mesa 06-073-0006 0.069 0.070 0.069 0.069

Kearny 

Villaa

06-073-1016 - - 0.066 0.066

Otay Mesa 06-073-2007 0.061 0.056 0.059 0.058

Source: AQS Preliminary Design Value Report. January 28, 2013. 

a2011 is the first year with complete data – the 4th maximum 

value is provided.

Table 2: Preliminary 4th Highest Daily Maximum 

8-Hour Ozone Concentrations for 2012

Monitor Site Code 4

th Highest 

Value (ppm)

Alpine 06-073-1006 0.080

Camp Pendleton 06-073-1008 0.059

Chula Vista 06-073-0001 0.064

Del Mar 06-073-1001 0.058

Downtown 06-073-1010 0.048

El Cajon 06-073-0003 0.067

Escondido 06-073-1002 0.065

Kearny Mesa 06-073-0006 incomplete 

datab

Kearny Villa 06-073-1016 0.066

Otay Mesa 06-073-2007 0.057

Source: same as table 1. 
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21

b The Kearny Mesa site closed February 2012

B. The Area Must Have a Fully Approved SIP Meeting Requirements 

Applicable for Purposes of Redesignation under Section 110 and 

Part D.

Section 107(d)(3)(E)(ii) and (v) require EPA to determine 

that the area has a fully approved applicable SIP under section 

110(k) that meets all applicable requirements under section 110 

and part D for the purposes of redesignation. 

1. Basic SIP Requirements under CAA Section 110

Section 110(a)(2) sets forth the general elements that a 

SIP must contain in order to be fully approved. EPA has analyzed 

the California SIP and determined that it is consistent with the 

requirements of section 110(a)(2). The San Diego County portion 

of the approved California SIP contains enforceable emission 

limitations; requires monitoring, compiling and analyzing of 

ambient air quality data; requires preconstruction review of new 

or modified stationary sources; provides for adequate funding, 

staff, and associated resources necessary to implement its 

requirements; and provides the necessary assurances that the 

State maintains responsibility for ensuring that the CAA 
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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22

requirements are satisfied in the event that San Diego County is 

unable to meet its CAA obligations.11

On numerous occasions, CARB has submitted and we have 

approved provisions addressing the basic CAA section 110 

provisions. There are no outstanding or disapproved applicable 

SIP submittals with respect to the San Diego County portion of 

the SIP that prevent redesignation of the San Diego County 8-

hour ozone nonattainment area for the 1997 8-hour ozone 

 

11 The applicable SIP for CARB and SDAPCD may be found at 

http://yosemite.epa.gov/r9/r9sips.nsf/Casips?readform&count=100&state=Califor

nia. We note that SIPs must be fully approved only with respect to applicable 

requirements for purposes of redesignation in accordance with section 

107(d)(3)(E)(ii). Thus, for example, CAA section 110(a)(2)(D) requires that 

SIPs contain certain measures to prevent sources in a state from 

significantly contributing to air quality problems in another state. However, 

the section 110(a)(2)(D) requirements for a state are not linked with a 

particular nonattainment area’s designation and classification in that state. 

EPA believes that the requirements linked with a particular nonattainment 

area’s designation and classification are the relevant measures to evaluate 

in reviewing a redesignation request. The transport SIP submittal

requirements, where applicable, continue to apply to a state regardless of 

the designation of any one particular area in the state. Thus, we do not 

believe that these requirements should be construed to be applicable 

requirements for purposes of redesignation. In addition, EPA believes that 

the other section 110 elements not connected with nonattainment plan 

submissions and not linked with an area’s attainment status are not 

applicable requirements for purposes of redesignation. The State will still 

be subject to these requirements after the San Diego County ozone planning 

area is redesignated. The section 110 and part D requirements that are linked 

with a particular area’s designation and classification are the relevant 

measures to evaluate in reviewing a redesignation request. 

This policy is consistent with EPA’s existing policy on applicability of 

conformity (i.e., for redesignations) and oxygenated fuels requirement. See 

Reading, Pennsylvania, proposed and final rulemakings 61 FR 53174-53176 

(October 10, 1996), 62 FR 24816 (May 7, 1997); Cleveland-Akron-Lorain, Ohio, 

final rulemaking 61 FR 20458 (May 7, 1996); and Tampa, Florida, final 

rulemaking 60 FR 62748 (December 7, 1995). See also the discussion of this 

issue in the Cincinnati redesignation 65 FR 37890 (June 19, 2000), in the 

Pittsburgh redesignation 66 FR 50399 (October 19, 2001), and in the South 

Coast redesignation 72 FR 6986 (February 14, 2007) and 72 FR 26718 (May 11, 

2007). Again, EPA believes that section 110 elements not linked to the area’s 

nonattainment status are not applicable for purposes of redesignation.
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23

standard. Therefore, we propose to conclude that CARB and San 

Diego County have met all SIP requirements for San Diego County 

applicable for purposes of redesignation under section 110 of 

the CAA (General SIP Requirements). 

2. Part D Requirements

a. Introduction

The CAA contains two sets of provisions, subparts 1 and 2, 

that address planning and emission control requirements for 

ozone nonattainment areas. Both of these subparts are found in 

title I, part D of the CAA; sections 171-179 and sections 181-

185, respectively. Subpart 1 contains general, less prescriptive 

requirements for all nonattainment areas of any pollutant, 

including ozone, governed by a NAAQS. Subpart 2 contains 

additional, more specific requirements for ozone nonattainment 

areas classified under subpart 2. 

b. Subpart 1 Requirements

The applicable subpart 1 requirements are contained in 

sections 172(c)(1)-(9) and 176 of the CAA. A thorough discussion 

of the requirements contained in section 172 can be found in the 

General Preamble for Implementation of Title I (57 FR 13498, 

April 16, 1992). 

Since EPA is proposing here to determine that the San Diego 

area has attained the 1997 ozone standard, under 40 CFR 51.918, 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

24

if these determinations are finalized, the requirements to 

submit certain planning SIPs related to attainment, including 

attainment demonstration requirements (the reasonably available 

control measure (RACM) requirement of section 172(c)(1) of the 

CAA, the reasonable further progress (RFP) and attainment 

demonstration requirements of sections 172(c)(2) and (c)(6) of 

the CAA, and the requirement for contingency measures for RFP 

and attainment in section 172(c)(9) of the CAA, would be 

suspended for the area as long as it continues to attain the 

NAAQS and would cease to apply upon redesignation. In addition, 

in the context of redesignations, EPA has interpreted 

requirements related to attainment as not applicable for 

purposes of redesignation. For example, in the General Preamble 

EPA stated that:

[t]he section 172(c)(9) requirements are directed at 

ensuring RFP and attainment by the applicable date. These 

requirements no longer apply when an area has attained the 

standard and is eligible for redesignation. Furthermore, 

section 175A for maintenance plans * * * provides specific 

requirements for contingency measures that effectively 

supersede the requirements of section 172(c)(9) for these

areas. See “General Preamble for the Interpretation of 
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25

Title I of the Clean Air Act Amendments of 1990, (General 

Preamble) 57 FR 13498, 13564 (April 16, 1992).

See also Calcagni memo (“The requirements for reasonable further 

progress and other measures needed for attainment will not apply 

for redesignations because they only have meaning for areas not 

attaining the standard.”).

Each subpart 1 requirement and how it is addressed with 

respect to the San Diego 8-hour area is described below. 

 Implementation of all RACM, including, at a minimum, 

reasonably available control technology for existing sources 

and attainment of the standard (section 172(c)(1)).

Section 172(c)(1) requires the plans for all nonattainment 

areas to provide for the implementation of all RACM as 

expeditiously as practicable and to provide for attainment of 

the primary NAAQS. EPA interprets this requirement to impose a 

duty on all nonattainment areas to consider all available 

control measures and to adopt and implement such measures as are

reasonably available for implementation in each area as 

components of the area’s attainment demonstration. Because

attainment has been reached, no additional measures are needed 

to provide for attainment, and the section 172(c)(1) requirement 

is no longer considered to be applicable as long as the area 
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

26

continues to attain the standard until redesignation. See 40 CFR 

51.918.

 Reasonable further progress (section 172(c)(2)).

The RFP requirement under section 172(c)(2) is defined as 

progress that must be made toward attainment. This requirement 

is not relevant for purposes of redesignation because the San 

Diego County area has monitored attainment of the ozone NAAQS. 

See General Preamble (57 FR 13564, April 16, 1992). See also 40 

CFR 51.918. 

 A comprehensive, accurate, current inventory of actual 

emissions from all sources of the relevant pollutant or 

pollutants in the area (section 172(c)(3)).

CAA section 172(c)(3) requires states submit a

comprehensive, accurate, current inventory of actual VOC and NOx

emissions for the baseline year from all sources within the 

nonattainment area. The inventory is to address actual VOC and 

NOx emissions during the ozone season, and all stationary 

(generally referring to larger stationary source or point 

sources), area (generally referring to smaller stationary and 

fugitive (non-smokestack) sources), and mobile (on-road, 

nonroad, locomotive and aircraft) sources are to be included in 

the inventory. We interpret the Act such that the emission 

inventory requirements of section 172(c)(3) are satisfied by the 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

27

inventory requirements of the maintenance plan. See 57 FR 13498, 

at 13564 (April 16, 1992). Thus, our proposed approval of the 

San Diego 8-hour maintenance plan and related VOC and NOx

emission inventories and our proposed approval of CARB's 

redesignation request would satisfy the requirements of section 

172(c)(3) for the purposes of redesignation of the San Diego 8-

hour area to attainment for the 1997 ozone NAAQS. 

 Identification and quantification of the emissions, if any, of 

any such pollutants which will be allowed in accordance with 

section 173(a)(1)(B)(i.e., new or modified stationary sources 

located in established economic development zones) (section 

172(c)(4)).

Section 172(c)(4) requires the identification and 

quantification of allowable emissions for major new and modified 

stationary sources in a zone identified by the Administrator, in 

consultation with the Secretary of Housing and Urban 

Development, as a zone where economic development should be 

targeted. We note that the State has not sought to exercise the 

option available under CAA section 172(c)(4) (identification and 

quantification of certain emissions increases).

 Permits for the construction and operation of new and modified 

major stationary sources in the nonattainment area (section 

172(c)(5)).
This document is a prepublication version signed by EPA Regional 

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ensure the accuracy of this version, but it is not the official version.

28

Section 172(c)(5) requires source permits for the 

construction and operation of new and modified major stationary 

sources anywhere in the nonattainment area. To meet the 

requirements, states must submit SIP revisions that meet the 

requirements under 40 CFR 51.165 ("Permit requirements"), and 

EPA regulations at 40 CFR 51.914 extend the SIP requirements of 

40 CFR 51.165 to areas designated as nonattainment for the 1997 

8-hour ozone standard.

Under 40 CFR 51.165, states are required to submit SIP 

revisions that establish certain requirements for new or 

modified stationary sources in nonattainment areas, including

provisions to ensure that major new sources or major 

modifications of existing sources of nonattainment pollutants 

incorporate the highest level of control, referred to as the 

“Lowest Achievable Emission Rate” (LAER), and that increases in 

emissions from such stationary sources are offset so as to 

provide for reasonable further progress towards attainment in 

the nonattainment area. 

The process for reviewing permit applications and issuing 

permits for new or modified major stationary sources of air 

pollution is referred to as “New Source Review” (NSR). With 

respect to nonattainment pollutants in nonattainment areas, this 

process is often referred to as “nonattainment NSR.” With 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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29

respect to pollutants for which an area is designated as 

attainment or unclassifiable, states are required to submit SIP 

revisions that ensure that major new stationary sources and 

major modifications of existing stationary sources meet the 

federal requirements for “Prevention of Significant 

Deterioration" (PSD), including application of "Best Available 

Control Technology” (BACT), for each applicable pollutant 

emitted in significant amounts, among other requirements.

SDAPCD is responsible for stationary source emissions 

units, and SDAPCD regulations govern air pollutant permits 

issued for such units. Under the Clean Air Act Amendments of 

1977, states with designated nonattainment areas were required 

to amend their NSR rules to impose LAER and offset requirements 

on new major sources and major modifications of nonattainment 

pollutants in nonattainment areas. As noted previously, under 

the 1977 Act Amendments, we designated the San Diego Air Basin 

as a nonattainment area for photochemical oxidants, later 

changed to ozone. To address the nonattainment NSR requirements 

arising from the 1977 Act Amendments, SDAPCD amended its 

nonattainment NSR rules, and CARB submitted them to EPA for 

approval as part of the California SIP. In 1981, we approved the 

following amended NSR rules: 20 – Standards for Granting 

Applications; 20.1 - Definitions, Emission Calculations, 
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ensure the accuracy of this version, but it is not the official version.

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Emission Offsets and Banking, Exemptions, and Other 

Requirements; 20.2 - Standards for Authority to Construct - -

Best Available Air Pollution Control Technology; 20.3 -

Standards for Authority to Construct - - Air Quality Analysis; 

20.4 - Standards for Authority to Construct - - Best Available 

Air Pollution Control Technology; 20.5 - Power Plants; and 20.6 

- Standards for Authority to Construct - - Air Quality Analysis.

See 46 FR 21749 (April 14, 1981). Under these SIP-approved 

rules, LAER and offsets have been required for new "point 

sources" that cause emissions greater than 100 tons per year of 

ozone precursors in ozone nonattainment areas. 

The 1990 Clean Air Act Amendments retained the core 

nonattainment NSR elements of LAER and offsets but revised the 

applicability thresholds based on an area’s non-attainment 

classification. The San Diego 8-hour area is currently 

classified as a moderate ozone non-attainment area, and 

therefore the NSR applicability thresholds at which LAER and 

offsets are required is 100 tpy of NOx or VOC for new sources and 

40 tpy for modifications made to existing major sources. EPA has 

reviewed SDAPCD’s existing SIP-approved NSR rules and determined 

that they meet the current 40 CFR 51.165 requirements related to 

the application of LAER and offsets for areas classified as 

moderate for ozone. Thus, San Diego County has a nonattainment 
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ensure the accuracy of this version, but it is not the official version.

31

NSR program meeting the requirements of 40 CFR 51.165 for 

sources within the San Diego 8-hour area.

SDAPCD does not currently have an approved PSD program.

Even if EPA finalizes the actions in today's proposed 

rulemaking, the federal PSD requirements under 40 CFR 52.21 

will not apply to new major sources or major modifications to 

existing major sources of ozone precursors under SDAPCD’s 

jurisdiction until the San Diego County 8-hour area is 

redesignated to attainment for the 2008 ozone standard. On April 

4, 2012, SDAPCD adopted Rule 20.3.1 to address PSD requirements, 

and CARB submitted the rule to EPA on February 13, 

2013 for inclusion in the SIP. If it is approved by EPA, SDAPCD

will have a SIP-approved PSD program.

 Enforceable emission limitations as may be necessary or 

appropriate to provide for attainment of such standard in such 

area by the applicable attainment date (section 172(c)(6)).

Section 172(c)(6) requires the SIP to contain control 

measures necessary to provide for attainment of the standard.

Because attainment has been reached, no additional measures are 

needed to provide for attainment.

 Compliance with section 110(a)(2) of the Act (section 

172(c)(7)).
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Section 172(c)(7) requires the SIP to meet the applicable 

provisions of section 110(a)(2). As noted above, we believe the 

California SIP meets the requirements of section 110(a)(2) 

applicable for purposes of redesignation.

 Use of equivalent modeling emission inventory, and planning 

procedures if approved by EPA (CAA section 172(c)(8)).

The State of California has not sought to exercise the 

options available under CAA section 172(c)(8).

 Contingency measures for RFP and attainment of the NAAQS (CAA 

section 172(c)(9)).

Because the San Diego 8-hour area has attained the 1997 

ozone NAAQS and is no longer subject to an RFP requirement, the 

requirement to submit the section 172(c)(9) contingency measures 

is not applicable for purposes of redesignation. See General 

Preamble (57 FR 13564, April 16, 1992). See also 40 CFR 51.918.

 Interagency consultation and enforceability for the purposes 

of transportation conformity (CAA section 176(c)(5) and 40 CFR 

51.390).

Under section 176(c) of the Clean Air Act Amendments of 

1990, states are required to establish criteria and procedures 

to ensure that federally supported or funded projects conform to

the air quality planning goals in the applicable SIP. Section 

176(c) further provides that state conformity provisions must be 
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consistent with federal conformity regulations that the CAA 

requires EPA to promulgate. EPA’s conformity regulations are 

codified at 40 CFR part 93, subparts A (referred to herein as 

“transportation conformity”) and B (referred to herein as 

“general conformity”). Transportation conformity applies to 

transportation plans, programs, and projects developed, funded, 

and approved under title 23 U.S.C. or the Federal Transit Act, 

and general conformity applies to all other federally-supported 

or funded projects. SIP revisions intended to address the 

conformity requirements are referred to herein as “conformity 

SIPs.”

EPA believes it is reasonable to interpret the conformity 

SIP requirements as not applying for purposes of a redesignation 

request under section 107(d) because state conformity rules are 

still required after redesignation and federal conformity rules 

apply where state rules have not been approved. See Wall v. EPA,

265 F. 3d 426 (6th Cir. 2001), upholding this interpretation. 

See also, 60 FR 62748 (December 7, 1995).

c. Subpart 2 Requirements

With respect to the requirements associated with subpart 2, 

we note that, as discussed in more detail above, the San Diego 

8-hour area is classified as moderate nonattainment for the 1997 

ozone standard under subpart 2 of part D of the CAA. See 77 FR 
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28424 (May 14, 2012). EPA issued a final rule classifying the 

San Diego 8-hour area as moderate for the 1997 ozone standard, 

along with a number of other areas of the country (2012 ozone 

classification). States with these affected areas, including 

California, were given one year from the effective date of the 

2012 ozone classification to submit SIP revisions that applied 

to the areas as a result of their new classification. See 77 FR 

28426 and 28429 (May 14, 2012). The effective date of EPA's 

classification of the San Diego 8-hour area as moderate for the 

1997 ozone standard was June 13, 2012. Therefore, the deadline 

for California to submit any necessary SIP revisions that are 

now required for the San Diego 8-hour area, due to the area’s

new moderate classification, is June 13, 2013.

CARB has not submitted any SIP revisions for the San Diego 

8-hour area in response to the area's 2012 ozone classification 

as moderate. However, as EPA articulated in the 2012 ozone 

classification, EPA believes that this fact does not preclude 

redesignation based upon the following factors: (1) EPA’s 

longstanding policy of evaluating requirements in accordance 

with the requirements due at the time a redesignation request is 

submitted; and (2) consideration of the inequity of applying 

retroactively any requirements that might in the future be 

applied.
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First, CARB submitted the redesignation request on December 

28, 2012, well before the State’s June 13, 2013 deadline to 

submit subpart 2 requirements. Under EPA’s longstanding 

interpretation of section 107(d)(3)(E) of the CAA states 

requesting redesignation to attainment must meet only the 

relevant SIP requirements that came due prior to the submittal 

of a complete redesignation request. See the Calcagni memo and 

September 17, 1993, Michael Shapiro Memorandum ("State 

Implementation Plan (SIP) Requirements for Areas Submitting 

Requests for Redesignation to Attainment of the Ozone and Carbon 

Monoxide (CO) National Ambient Air Quality Standards (NAAQS) on 

or after November 15, 1992," Memorandum from Michael Shapiro, 

Acting Assistant Administrator for Air and Radiation), and: 60 

FR 12459, 12465–66 (March 7, 1995) (Redesignation of Detroit-Ann 

Arbor, Michigan); Sierra Club v. EPA, 375 F.3d 537 (7th Cir. 

2004) (upholding this interpretation); and 68 FR 25418, 25424, 

25427 (May 12, 2003) (redesignation of St. Louis, Missouri). 

Moreover, it would be inequitable to retroactively apply 

any new SIP requirements that were not applicable at the time 

the request was submitted. The D.C. Circuit Court (Court) has 

recognized the inequity in such retroactive rulemaking (see 

Sierra Club v. Whitman, 285 F. 3d 63 (D.C. Cir. 2002)), in which 

the Court upheld a district court’s ruling refusing to make 
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ensure the accuracy of this version, but it is not the official version.

36

retroactive an EPA determination of nonattainment that was past 

the statutory due date. Such a determination would have resulted 

in the imposition of additional requirements on the area. The 

Court stated, "[a]lthough EPA failed to make the nonattainment 

determination within the statutory frame, Sierra Club’s proposed 

solution only makes the situation worse. Retroactive relief 

would likely impose large costs on the states, which would face 

fines and suits for not implementing air pollution prevention 

plans in 1997, even though they were not on notice at the time." 

Id. at 68. Similarly here, it would be unfair to penalize the 

San Diego 8-hour area by applying to it, for purposes of 

redesignation, additional SIP requirements under subpart 2 that 

were not in effect or yet due at the time it submitted its 

redesignation request, or the time that the San Diego 8-hour 

area attained the 1997 ozone NAAQS. 

Based on the above, EPA proposes to find that the San Diego 

8-hour area has a fully approved SIP meeting requirements 

applicable for purposes of redesignation under CAA section 110 

and title I part D. 

C. The Area Must Show the Improvement in Air Quality is Due to 

Permanent and Enforceable Emissions Reductions.

Section 107(d)(3)(E)(iii) precludes redesignation of a 

nonattainment area to attainment unless EPA determines that the 
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37

improvement in air quality is due to permanent and enforceable 

reductions in emissions resulting from implementation of the 

applicable SIP and applicable federal air pollution control 

regulations and other permanent and enforceable regulations. 

Under this criterion, the state must be able to reasonably 

attribute the improvement in air quality to emissions reductions 

which are permanent and enforceable. Attainment resulting from 

temporary reductions in emissions rates (e.g., reduced 

production or shutdown due to temporary adverse economic 

conditions) or unusually favorable meteorology would not qualify 

as an air quality improvement due to permanent and enforceable 

emission reductions.

Table 3 summarizes the reductions in ozone precursors 

(i.e., VOCs and NOx) between 2002 and 2011 sufficient to attain 

the 1997 ozone standard in the San Diego County 8-hour ozone 

nonattainment area (San Diego 8-hour area). 

Table 3. San Diego County 2002-2011 Reductions in Ozone 

Precursor Emissions (tons per day, tpd).12

Source 

Category

VOC 

2002

VOC 

2011

VOC 

Reduction

NOx

2002

NOx

2011

NOx

Reduction

Consumer 

Solvent 

Products

22.5 17.9 3% - - --

 

12 Emissions data reflect a “summer day,” as required by EPA policy guidance. 

Emissions data assume no emissions reductions from NSR or Title V permit 

programs. Source category-specific data are listed in Appendix A of the San 

Diego 8-hour maintenance plan. Emission reduction percentages are relative to 

the 2002 base year emissions totals of 183 tpd of VOC and 198 tpd of NOx for 

the entire SDAPCD.
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On-road 

Motor 

Vehicles

63.4 35.3 15% 119.9 70.9 25%

Non-road 

Mobile 

Sources

49.1 40.3 5% 68.0 58.6 5%

Stationary & 

Area Sources 48.0 49.1 0% 10.1 8.1 1%

TOTAL 183.1 142.6 22% 198.1 137.5 31%

Source: California Air Resources Board, Southern California 

2012 SIP Baseline Emission Projection – Version 1.02 Planning 

Inventory Tool website.

The effectiveness of the control measures to reduce VOC and 

NOx emissions can be assessed by comparing emissions in 2002 (the 

nonattainment base year, for planning purposes) with those in 

2011 (an attainment year for the area). The emission reductions 

presented in table 3 were calculated relative to the 2002 base 

year emissions inventory of 183 tpd of VOC and 198 tpd of NOx. 

Between 2002 and the 2011 attainment year VOC and NOx emissions 

were reduced 22% and 31%, respectively. On-road motor vehicle 

control programs provided reductions of 15% and 25% of the VOC 

and NOx, and non-road mobile sources control programs resulted in 

reductions of 5% from both VOC and NOx. These reductions were 

achieved despite an increase in population and vehicle miles

traveled (VMT) of approximately 7% and 9%, respectively, during 

the same time period.

13

 

13 See Figure 4-1 in the San Diego 8-hour maintenance plan. Additional 

information provided in personal communication (via email) from Carl Selnick, 

SDAPCD, to John Ungvarsky, USEPA, on January 2, 2013.
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The emissions reductions between 2002 and 2011 resulted 

primarily from EPA and CARB mobile source control programs. 

SDAPCD’s stationary source control programs had mostly been 

implemented and provided significant emissions reductions prior 

to 2002; however, SDAPCD Rules 67.6.1 – Cold Solvent Cleaning 

and Stripping Operations and 67.6.2 – Vapor Degreasing 

Operations,14 adopted in 2007, provided an additional 1 tpd of 

VOC reductions towards attainment, and these reductions occurred 

after the 2002 base year. 

Source categories for which CARB has primary 

responsibility for reducing emissions in California include most 

new and existing on- and off-road engines and vehicles, motor 

vehicle fuels, and consumer products. In addition, California 

has unique authority under CAA section 209 (subject to being 

granted a waiver by EPA) to adopt and implement new emission 

standards for many categories of on-road vehicles and engines, 

and new and in-use off-road vehicles and engines. California has 

been a leader in the development of some of the most stringent 

control measures nationwide for on-road and off-road mobile 

sources and the fuels that power them. These measures have 

 

14 These rules were approved by EPA on October 13, 2009. See 74 FR 52427. EPA 

intends to act in the coming months on SDAPCD Rules 67.0 - Architectural 

Coatings (amended) and 67.11 - Wood Products Coating Operation, for possible 

inclusion in the SIP. Documentation included in the submittal to EPA for 

these two rules indicates that together they have achieved approximately 1.5 

tpd in VOC reductions. And again, these reductions occurred after the 2002 

base year.
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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40

helped reduce VOC and NOx in the San Diego ozone nonattainment 

area and throughout the State.

CARB has provided a summary of the measures adopted and 

implemented by the State. See “Air Resources Board’s Proposed 

State Strategy for California’s 2007 State Implementation Plan,” 

release date: April 26, 2007 (2007 State Strategy). From 1994 to 

2006, the State took approximately 45 rulemaking actions which 

have achieved significant emission reductions contributing to 

attainment and continued attainment in the San Diego 8-hour

area. See 2007 State Strategy, p. 38.15 These measures include 

new emission standards and in-use requirements that have 

resulted in significant reductions in emissions of VOCs and NOx

from mobile source categories such as passenger cars, trucks, 

buses, motorcycles, locomotives, cargo handling equipment, and 

large off-road equipment. EPA has generally approved all of the 

State’s measures that the State has submitted to EPA as 

revisions to the SIP and that are not subject to the CAA section 

209 waiver process. See, for example, EPA’s final approval of 

the San Joaquin Valley PM2.5 plan at 76 FR 69896 (November 9, 

2011) and accompanying Technical Support Document and Responses 

 

15 The 2007 State Strategy can be found at: 

http://arb.ca.gov/planning/sip/2007sip/apr07draft/sipback.pdf. See page 38 for 

a list of actions.
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to Comments.

16 Since 2006, ARB has adopted additional measures 

that will provide further reductions in the San Diego 8-hour

area. The 2007 State Strategy measures listed in table 4 reduce 

emissions of VOCs and NOx and have been approved into the SIP or 

granted a waiver. 

Table 4. Status of Control Measures in CARB’s 2007 State 

Strategy Contributing Towards Attainment and/or Continued 

Attainment of the 1997 Ozone NAAQS in the San Diego 8-hour 

area.

Measure Date of Adoption Current Status

Modifications to 

Reformulated 

Gasoline

June 14, 2007 Approved 75 FR 

26653, May 12, 

2010.

Clean Up Existing 

Harbor Craft

November 15, 2007 Waiver granted; 76 

FR 77521, December 

13, 2011.

Ship Auxiliary 

Engine Cold Ironing 

and Clean 

Technology

December 6, 2007 Waiver granted; 76 

FR 77515, December 

13, 2011.

Consumer Products 

Program Regulations

May 6, 2005; 

September 26, 2007;

May 5, 2009;

August 6, 2010

Approved: 74 FR 

57074, November 4, 

2009; 

76 FR 27613, May 

12, 2011; 

77 FR 7535,

February 13, 2012.

Smog Check 

Improvements

August 31, 2009 Elements approved 

75 FR 38023, July 

1, 2010.

Cleaner In-Use 

Heavy-Duty Trucks

December 16, 2010 Approved 77 FR 

 

16 This document, titled “Technical Support Document and Responses to 

Comments: Final Rule on the San Joaquin Valley 2008 PM2.5 State Implementation 

Plan,” dated September 30, 2011, can be found on the Internet in the docket 

for EPA’s final approval of the San Joaquin Valley plan to attain the 1997 

PM2.5 NAAQS at: http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR2010-0516-0175.
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20308, April 4, 

2012.

Cleaner In-Use OffRoad EquipmentDecember 17, 2010 Waiver decision 

pending.

Port Truck 

Modernization

December 17, 2010 Adopted December 

2007 and December 

2008.

A detailed list of the SDAPCD, CARB, and EPA measures, 

including those adopted and implemented prior to 2002, 

contributing to attainment and maintenance of the 1997 ozone 

standard can be found in Appendix B of the San Diego 8-hour 

maintenance plan.

17

We note that the control measures cited in the San Diego 8-

hour maintenance plan, in particular those for on-road and nonroad sources, have provided emissions reductions since 2002, and 

thus, the improvement in air quality since 2002 may reasonably 

be attributed to them. For instance, the federal gasoline and 

diesel fuel standards adopted in 2010 (65 FR 6698, February 10, 

2000) have greatly lowered the allowable sulfur content of fuels 

and resulted in lower emissions, especially NOx, from cars and 

trucks. The State and federal on-road and nonroad vehicle and 

 

17 In addition, the U.S. Secretary of State has accepted the designation by 

the International Maritime Organization of an Emission Control Area (ECA) in 

the waters off the North American coasts. Under this designation, ships are 

required to meet tighter fuel and emissions standards than would otherwise 

apply. Within the North American ECA, the effective date of the first-phase 

fuel sulfur standard was August 2012, and the second phase begins January 

2015. Beginning in 2016, NOx aftertreatment requirements become applicable. 

San Diego County will benefit from the ECA because ships complying with ECA 

standards will reduce their emissions of NOx, sulfur oxides, and fine 

particulate matter. Appendix B of the San Diego 8-hour maintenance plan does 

not include this measure.
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engine standards have contributed to improved air quality 

through the gradual, continued turnover and replacement of older 

model vehicles with newer model vehicles manufactured to meet 

increasingly stringent tailpipe emissions standards. 

With respect to the connection between emissions reductions 

and improvement in air quality, we also conclude that the air 

quality improvement since 2002 in the San Diego 8-hour area is 

not the result of a local economic downturn or unusual or 

extreme weather patterns. San Diego did not observe any anomaly 

over the period from 2002 to 2011 relative to long-term 

averages. We do recognize that a significant economic slowdown 

occurred nationally starting in 2008, but we note that the 

downward trend in VOC and NOx emissions had already been 

established before that time.18 We also reviewed temperature data

for the 1993-2011 period19 and the analysis of this data included 

in the San Diego 8-hour maintenance plan. The data indicate that 

although the 2009-2011 attainment period was slightly cooler 

than the long-term average, there were six other three-year 

periods since 1993 that were at least as cool or cooler than the 

2009-2011 period, that also had 8-hour design values above the 

1997 ozone NAAQS. Thus, the temperature records support the 

 

18 See Figure 4-1, titled “San Diego County VOC + NOx Emission Reductions 

Despite Growth,” on page 4-3 of the San Diego 8-hour maintenance plan.

19 See Figure 4-2, titled “San Diego County Three-Year Average Ozone Season 

Daily Maximum Temperatures,” on page 4-5 of the San Diego 8-hour maintenance 

plan.
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conclusion that attainment did not result from unusually 

favorable meteorology during 2009-2011.

We find that the improvement in air quality in the San 

Diego 8-hour area is the result of permanent and enforceable 

emissions reductions from a combination of federal vehicle and 

fuel measures and EPA-approved state and local control measures. 

As such, we propose to find that the criterion for redesignation 

set forth at CAA section 107(d)(3)(E)(iii) is satisfied.

D. The Area Must Have a Fully Approved Maintenance Plan under 

CAA Section 175A.

Section 175A of the CAA sets forth the elements of a 

maintenance plan for areas seeking redesignation from 

nonattainment to attainment. We interpret this section of the 

Act to require, in general, the following core elements: 

attainment inventory, maintenance demonstration, monitoring 

network, verification of continued attainment, and contingency 

plan. See Calcagni memo, pages 8 through 13. 

Under CAA section 175A, a maintenance plan must demonstrate 

continued attainment of the applicable NAAQS for at least ten 

years after EPA approves a redesignation to attainment. Eight 

years after redesignation, the State must submit a revised 

maintenance plan that demonstrates continued attainment for the 

subsequent ten-year period following the initial ten-year 
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45

maintenance period. To address the possibility of future NAAQS 

violations, the maintenance plan must contain such contingency 

provisions, that EPA deems necessary, to promptly correct any 

violation of the NAAQS that occurs after redesignation of the 

area to attainment. Based on our review and evaluation of the 

plan, as detailed below, we are proposing to approve the San 

Diego maintenance plan because we believe that it meets the 

requirements of CAA section 175A. 

1. Attainment Inventory

A maintenance plan for the 1997 8-hour ozone standard must 

include an inventory of emissions of ozone precursors (VOC and 

NOx) in the area to identify a level of emissions that are 

sufficient to attain the 1997 ozone NAAQS. This inventory must 

be consistent with EPA’s most recent guidance on emissions 

inventories for nonattainment areas available at the time and 

should represent emissions during the time period associated 

with the monitoring data showing attainment. The inventory must 

also be comprehensive, including emissions from stationary, 

area, nonroad mobile, and on-road mobile sources, and must be 

based on actual “ozone season data” (i.e., summertime) 

emissions. 

SDAPCD selected year 2011 as the year for the attainment 

inventory in the San Diego maintenance plan. The attainment 
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inventory will generally be the actual inventory during the time 

period the area attained the standard. Thus, SDAPCD's selection 

of 2011 for the attainment inventory is acceptable. 

In addition to the 2011 attainment inventory, the San Diego 

8-hour maintenance plan also includes emissions inventories for 

2002, 2015, 2020, and 2025. Based on our review of the San Diego 

8-hour maintenance plan, we find that the emissions inventories 

in the plan are comprehensive in that they include estimates of 

VOC and NOx emissions for 2002, 2011, 2015, 2020, and 2025 from 

69 relevant source categories, which the plan groups among 

stationary, areawide, on-road mobile, and non-road mobile 

sources. See tables A-1 and A-2 in Appendix A of the San Diego 

8-hour maintenance plan.

The stationary source category includes non-mobile, fixed 

sources of air pollution. Examples of sources included in this 

category include fuel combustion (e.g., electric utilities), 

waste disposal (e.g., landfills), and oil and gas production. 

SDAPCD’s 2002, 2011, 2015, 2020, and 2025 inventories for 

stationary sources were developed using ARB’s Southern 

California 2012 SIP Baseline Emission Projection – Version 1.02 

Planning Inventory Tool, which is based on methodologies in 

CARB’s California Almanac of Emissions and Air Quality – 2009 
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Edition (CARB’s 2009 Almanac).

20 Information reported by emission 

sources to SDAPCD and entered into the California Emission 

Inventory Development and Reporting System (CEIDARS) database21

was also used to generate actual emissions data for stationary 

sources. For areawide sources, CARB calculated emissions based 

on reported data for fuel usage, product sales, population, 

employment data, and other parameters covering a wide range of 

activities.22 

The on-road mobile source category consists of mobile 

sources such as trucks, automobiles, buses, and motorcycles. The 

on-road emissions inventory estimates in the San Diego 8-hour 

maintenance plan were prepared by CARB using EMFAC2011, a CARB

model for on-road motor vehicle emissions.23 The vehicle miles 

traveled estimates needed for input into the emissions model 

were developed by the San Diego Association of Governments 

 

20 CARB’s 2009 Almanac contains information about current and historical air

quality and emissions in California. In addition, forecasted emissions

are presented. See http://www.arb.ca.gov/aqd/almanac/almanac09/almanac09.htm.

21 The CEIDARS database consists of two categories of information: source 

information (for further information, see: 

http://www.arb.ca.gov/ei/drei/maintain/dbstruct.htm#source) and utility 

information (for further information, see: 

http://www.arb.ca.gov/ei/drei/maintain/dbstruct.htm#utility). Source 

information includes the basic inventory information generated and collected 

on all point and area sources. Utility information generally includes 

auxiliary data, which helps categorize and further define the source 

information. Used together, CEIDARS is capable of generating complex reports 

based on a multitude of category and source selection criteria.

22 For more information on emissions from the area-wide source category, see 

the CARB web site: http://www.arb.ca.gov/ei/areasrc/areameth.htm.

23 See 78 FR 14533 (March 6, 2013) regarding EPA approval of the latest 

version of the California EMFAC model (short for EMissionFACtor) and 

announcement of its availability. The software and detailed information on 

the EMFAC vehicle emission model can be found on the following CARB web site:

http://www.arb.ca.gov/msei/msei.htm.
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(SANDAG) for the 2050 Regional Transportation Plan. The 

transportation modeling process used by SANDAG is described in 

Appendix B (Air Quality Planning and Transportation Conformity) 

of the 2050 Regional Transportation Plan.24

With respect to nonroad mobile sources, the category 

includes aircraft, trains and boats, and off-road vehicles and 

equipment used for construction, farming, commercial, 

industrial, and recreational activities. CARB used its 

OFFROAD2007 model to calculate the nonroad emissions.25 In 

general, emissions are calculated using equipment population, 

engine size and load, usage activity, and emission factors.

Tables 5 and 6 below present the VOC and NOx emissions 

inventory estimates contained in the San Diego 8-hour 

maintenance plan for actual 2011 emissions and projected 2015, 

2020, and 2025 emissions. Based on the 2011 estimates in tables 

5 and 6, mobile sources accounted for 53% of the VOC and 94% of 

NOx emissions within the San Diego 8-hour area. Stationary 

sources, consumer products, and other areawide sources 

represented 22%, 12%, and 13% of VOC emissions, respectively. 

Stationary and areawide sources accounted for only 6% of the NOx

emissions. Future emissions levels for 2015, 2020, and 2025 are 

 

24 SANDAG’s transportation activity modeling process is described in Appendix 

B (Air Quality Planning and Transportation Conformity) of the 2050 Regional 

Transportation Plan, which can be found on the Internet at: 

http://www.sandag.org/index.asp?projectid=349&fuseaction=projects.detail.

25 See http://www.arb.ca.gov/msei/offroad/offroad.htm. 
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forecasted by adjusting the attainment year emissions inventory 

to reflect projected growth in emitting activities and 

additional control of emission rates that will be provided by 

continued implementation of the existing federal, State and 

SDAPCD emissions control regulations. Growth in emitting 

activities is projected based on forecasted growth in socioeconomic factors such as population, employment, industrial 

production, and vehicle miles of travel.

Table 5. 2011 and Projected 2015, 2020, and 2025 VOC Emissions

Total Daily Emissions (tpd, average summer weekday)

Source Category

VOC 

2011 2015 2020 2025

Stationary 31.1 33.1 35.8 36.8

Consumer Products 17.9 16.9 17.6 18.3

Other Areawide 18.0 18.4 19.1 19.2

On-road Motor Vehicles 35.3 26.4 20.5 18.3

Non-road Mobile 40.3 37.1 35.4 36.1

Banked Emission Credits - 0.9 0.9 0.9

Military26 - 1.0 1.0 1.0

TOTAL 142.6 133.9 130.3 130.6

Source: Appendix A, San Diego 8-hour maintenance plan. 

Table 6. 2011 and Projected 2015, 2020, and 2025 NOx Emissions

Total Daily Emissions (tpd, average summer weekday)

Source Category

NOx

2011 2015 2020 2025

 

26 Because potential changes in military activities do not follow socioeconomic factors, SDAPCD obtained from the Department of the Navy, for 

inclusion in the maintenance demonstration, a projection of future mobile 

source emissions from potential additional military activity (beyond that 

assumed in the baseline emissions) that may occur during the maintenance 

period at Coast Guard, Navy, and Marine Corps facilities in San Diego County. 

See “Department of Navy Emissions Growth Increment Request for the San Diego 

Air Pollution Control District,” May 24, 2011.
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Stationary 6.3 5.6 5.5 5.6

Areawide 1.7 1.8 1.9 2.0

On-road Motor Vehicles 70.9 52.5 35.9 27.6

Non-road Mobile 58.6 54.9 50.4 47.5

Banked Emission Credits - 0.7 0.7 0.7

Military27 - 4.4 4.4 4.4

TOTAL 137.5 119.9 98.9 87.8

Source: Appendix A, San Diego 8-hour maintenance plan.

Based on our review of the emissions inventories (and 

related documentation) from the San Diego 8-hour maintenance 

plan, we find that the 2011 attainment year emissions inventory

is comprehensive, that the methods and assumptions used by 

SDAPCD and CARB to develop the inventory are reasonable, and 

that the inventory reasonably estimates actual ozone season 

emissions in the 2011 attainment year. Moreover, we find that 

the 2011 emissions inventory reflects the latest planning 

assumptions and emissions models available at the time the plan 

was developed, and provides a comprehensive and reasonably 

accurate basis upon which to forecast ozone precursor emissions 

for years 2015, 2020 and 2025.

2. Maintenance Demonstration

CAA section 175A(a) requires that the maintenance plan 

“provide for the maintenance of the national primary ambient air 

quality standard for such air pollutant in the area concerned 

for at least 10 years after the redesignation.” Generally, a 

state may demonstrate maintenance of the 1997 ozone standard by 

 

27 See previous footnote.
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either showing that future emissions will not exceed the level 

of the attainment year inventory or by modeling to show that the 

future mix of sources and emissions rates will not cause a 

violation of the NAAQS. For areas that are required under the 

Act to submit modeled attainment demonstrations, the maintenance 

demonstration should use the same type of modeling. See Calcagni 

memo, page 9. The San Diego 8-hour area was not required to 

submit a modeled attainment demonstration, and thus, the San 

Diego 8-hour maintenance plan may demonstrate maintenance based 

on a comparison of existing and future emissions of ozone 

precursors.28

In addition to accounting for area-wide growth trends, 

SDAPCD included a growth increment for potential future military 

projects that may become operational during the maintenance 

period at Coast Guard, Navy, or Marine Corps facilities in the 

San Diego 8-hour area. SDAPCD also added to the maintenance-year 

inventory banked emissions reduction credits (ERCs) of 0.9 tpd 

of VOCs and 0.7 tpd of NOx from stationary sources in the event 

that the ERCs are used for the purpose of issuing permits for 

new or modified stationary sources in the San Diego 8-hour area. 

We have reviewed the methods and assumptions, as described in 

connection with the attainment year inventory, that SDAPCD and 

 

28 A maintenance demonstration need not be based on ozone modeling. See Wall 

v. EPA, 375 F.3d 537 (7th Cir. 2004). See also 66 FR 53094, at pages 53099-

53100 (October 19, 2001), and 68 FR 25413, pages 25430-25432 (May 12, 2003).
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CARB used to project emissions to 2015, 2020, and 2025 for the 

various source categories and find the methods and assumptions

to be reasonable.

Tables 5 and 6 compare the VOC and NOx emissions estimated 

for the San Diego 8-hour area for the 2011 attainment year with 

the 2015 and 2020 interim years, and 2025 maintenance year. By 

2025, San Diego County ozone precursor emissions are projected 

to decrease by 12.1 tons per day (8%) for VOC and 49.7 tons per 

day (36%) for NOx relative to the 2011 attainment year inventory. 

The projected VOC and NOx emissions show that VOC and NOx

emissions would remain well below the attainment year levels 

through 2025 and thereby adequately demonstrate maintenance 

through at least a 10-year period. 

3. Monitoring Network

Continued ambient monitoring of an area is generally 

required over the maintenance period. As discussed in section 

V.A of this document, ozone is currently monitored by SDAPCD at 

nine sites within the San Diego 8-hour area. SDAPCD also commits 

to continue operating the ambient ozone monitoring network, 

quality assuring the resulting monitoring data, and entering all 

data into the AQS in accordance with federal requirements and 

guidelines to verify continued attainment of the 1997 8-hour 
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ozone NAAQS.29 See page 5-5 of the San Diego 8-hour maintenance 

plan. We find SDAPCD’s commitment for continued ambient ozone 

monitoring as set forth in its San Diego 8-hour maintenance plan

to be acceptable.

4. Verification of Continued Attainment

CARB and SDAPCD have the legal authority to implement and 

enforce the requirements of the San Diego 8-hour maintenance 

plan. This includes the authority to adopt, implement and 

enforce any emission control contingency measures determined to 

be necessary to correct violations of the 1997 ozone standard. 

To verify continued attainment, SDAPCD commits to the continued 

operation of an ozone monitoring network in accordance with 

federal requirements and guidelines to verify continued 

attainment of the 1997 ozone standard. SDAPCD also commits to 

annually reviewing ozone monitoring data from the three most 

recent, consecutive years to verify continued attainment of the 

1997 ozone standard through the maintenance period.

In addition, the transportation conformity process, which 

requires a comparison of on-road motor vehicle emissions that 

would occur under new or amended regional transportation plans 

and programs with the MVEBs in the San Diego 8-hour maintenance 

 

29 Although the San Diego 8-hour maintenance plan is not explicit in this 

regard, we presume that SDAPCD's intention to continue operation of a 

monitoring network means that the agency intends to do so consistent with 

EPA’s monitoring requirements in 40 CFR part 58 (“Ambient Air Quality 

Surveillance”).
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plan, represents another means by which to verify continued 

attainment of the 1997 ozone standard in the San Diego 8-hour 

area. This alternate means of verifying continued attainment 

during the maintenance period is especially relevant for the San 

Diego 8-hour area, given the importance of motor vehicle 

emissions to the overall emissions inventories of ozone 

precursors in the area. It is important to note also that 

conformity applies to an area during its entire maintenance 

period. See page 5-3 of the San Diego 8-hour maintenance plan. 

Lastly, while not cited in the San Diego 8-hour maintenance 

plan, CARB and SDAPCD must inventory emissions sources and 

report to EPA on a periodic basis under 40 CFR part 51, subpart 

A ("Air Emissions Reporting Requirements"). These emissions 

inventory updates will provide a third means with which to track 

emissions in the area relative to those projected in the 

maintenance plan and thereby verify continued attainment of the 

1997 ozone standard. These methods are sufficient for the 

purpose of verifying continued attainment.

5. Contingency Provisions

Section 175A(d) of the Act requires that maintenance plans 

include contingency provisions, as EPA deems necessary, to 

promptly correct any violations of the NAAQS that occur after 

redesignation of the area to attainment. Such provisions must 
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include a requirement that the state will implement all measures 

with respect to the control of the air pollutant concerned which 

were contained in the SIP for the area before redesignation of 

the area as an attainment area. 

Under section 175A(d), contingency measures identified in 

the contingency plan do not have to be fully adopted at the time 

of redesignation. However, the contingency plan is considered to 

be an enforceable part of the SIP and should ensure that the 

contingency measures are adopted expeditiously once they are 

triggered by a specified event. The maintenance plan should 

clearly identify the measures to be adopted, a schedule and 

procedure for adoption and implementation, and a specific 

timeline for action by the state. As a necessary part of the 

plan, the state should also identify specific indicators or 

triggers, which will be used to determine when the contingency 

measures need to be implemented.

As required by section 175A of the CAA, SDAPCD has adopted 

a contingency plan to address possible future ozone air quality 

problems. See section 5.7 of the San Diego 8-hour maintenance 

plan. SDAPCD commits to annually review ozone monitoring data 

from the three most recent, consecutive years to verify 

continued attainment of the 1997 ozone standard through the 

maintenance period.
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California's on-going emissions control program includes 

several recently adopted CARB mobile source control regulations 

(collectively referred to as California’s Advanced Clean Cars 

Program) that will be implemented and achieve additional 

reductions in the San Diego 8-hour area during the maintenance 

period regardless of monitored ozone levels. The Advanced Clean 

Cars Program (ACCP), adopted on January 27, 2012,30 will 

progressively tighten emissions control requirements for motor 

vehicles through model year 2025, and thus will provide 

additional emissions reductions over and above those needed for 

attainment and beyond those that are relied on to demonstrate 

maintenance in the San Diego 8-hour maintenance plan. The ACCP 

was not reflected in EMFAC2011, and the emissions inventories

used for the maintenance demonstration in the San Diego 8-hour

maintenance plan are based on EMFAC2011.

31 Therefore, the 

emission reductions from the ACCP are surplus to the maintenance 

demonstration, and thus the ACCP is eligible as a contingency 

measure.

The ACCP will provide continuing emissions reductions 

through the maintenance period and provide adequate additional 

reductions to address the CAA’s contingency requirements. By 

2025, the existing control program, not including CARB’s ACCP

 

30 On January 9, 2013, EPA approved CARB’s request for a waiver of preemption 

under section 209(b) for its ACC regulations. See 78 FR 2112.

31 See page 5-5 of San Diego 8-hour maintenance plan.
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adopted in 2012, is projected to reduce ozone precursor 

emissions in the San Diego 8-hour area by 20 tpd (14%) for VOC, 

and 52 tpd (39%) for NOx, below the 2011 attainment year 

emissions levels. Therefore, if new violations were to occur 

during the maintenance period, sufficient continuing emissions 

reductions are projected to ensure any violation will be quickly 

corrected and then provide for continued maintenance of the 1997 

ozone NAAQS in the San Diego 8-hour area through the maintenance 

period. In a March 6, 2013 letter to EPA, SDAPCD clarified 

information in the San Diego 8-hour maintenance plan by stating 

the ACCP is the initial contingency measure for promptly 

correcting a violation. If after implementation of the ACCP a 

subsequent violation occurs, SDAPCD commits to work with EPA and 

CARB to adopt and implement additional contingency measure(s), 

as deemed necessary, as soon as possible but no later than 12

months after the date of the second violation.

Upon our review of the plan and the March 6, 2013 

clarification, as summarized above, we find that the contingency 

provisions of the San Diego 8-hour maintenance plan identify 

specific contingency measures, contain tracking and triggering 

mechanisms to determine when contingency measures are needed, 

contain a description of the process of recommending and 

implementing contingency measures, and contain specific 
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timelines for action. Thus, we conclude that the contingency 

provisions of the San Diego 8-hour maintenance plan are adequate 

to ensure prompt correction of a violation and therefore comply 

with section 175A(d) of the Act.

6. Subsequent Maintenance Plan Revisions

CAA section 175A(b) provides that states shall submit a SIP 

revision eight years after redesignation providing for 

maintaining the NAAQS for an additional ten years. In the San 

Diego 8-hour maintenance plan, SDAPCD commits to prepare and 

submit a revised maintenance plan eight years after 

redesignation to attainment. See pages 5-6 of the San Diego 8-

hour maintenance plan.

7. Motor Vehicle Emissions Budgets

Transportation conformity is required by section 176(c) of 

the CAA. Our transportation conformity rule (codified in 40 CFR 

part 93, subpart A) requires that transportation plans, 

programs, and projects conform to SIPs and establishes the 

criteria and procedures for determining whether or not they do 

so. Conformity to the SIP means that transportation activities 

will not produce new air quality violations, worsen existing 

violations, or delay timely attainment of the national ambient 

air quality standards or delay any required interim milestones. 
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Ozone maintenance plan submittals must specify the maximum 

emissions of transportation-related VOC and NOx emissions allowed 

in the last year of the maintenance period, i.e., the motor 

vehicle emissions budgets (MVEBs). (MVEBs may also be specified 

for additional years during the maintenance period.) The MVEBs 

serve as a ceiling on emissions that would result from an area's 

planned transportation system. The MVEB concept is further 

explained in the preamble to the November 24, 1993, 

transportation conformity rule (58 FR 62188). The preamble 

describes how to establish MVEBs in the SIP and how to revise 

the MVEBs if needed.

A maintenance plan submittal must also demonstrate that 

these emissions levels, when considered with emissions from all 

other sources, are consistent with maintenance of the NAAQS. In 

order for us to find these emissions levels or “budgets” 

adequate and approvable, the submittal must meet the conformity 

adequacy provisions of 40 CFR 93.118(e)(4) and (5). For more 

information on the transportation conformity requirements and 

applicable policies on MVEBs, please visit our transportation 

conformity Web site at: 

http://www.epa.gov/otaq/stateresources/transconf/index.htm. 

EPA's process for determining adequacy of a MVEB consists 

of three basic steps: (1) providing public notification of a SIP 
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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submission; (2) providing the public the opportunity to comment 

on the MVEB during a public comment period; and, (3) making a 

finding of adequacy or inadequacy. The process for determining 

the adequacy of a submitted MVEB is codified at 40 CFR 93.118. 

The San Diego 8-hour maintenance plan contains new VOC and 

NOx MVEBs for 2020 and 2025 as shown in table 7. The MVEBs are 

the projected on-road mobile source VOC and NOx emissions for the 

San Diego 8-hour area for 2020 and 2025. They include a small

safety margin created by rounding up the projected on-road 

mobile source emissions to the next whole number and adding two

tons per day. The MVEBs are compatible with the 2020 and 2025 

on-road mobile source VOC and NOx emissions included in the San 

Diego 8-hour maintenance plan’s 2020 and 2025 VOC and NOx

emission inventories, as summarized above in tables 5 and 6. The 

conformity rule allows for a safety margin, and even with the 

small safety margin added to the on-road emissions, the overall 

emissions in the San Diego 8-hour area are consistent with 

continued maintenance of the 1997 ozone standard. The derivation 

of the MVEBs is discussed in section 5.3 of the San Diego 8-hour 

maintenance plan. The MVEBs incorporate: (1) on-road motor 

vehicle emission inventory factors of EMFAC2011; and (2) updated 

recent vehicle activity data from SANDAG generated using 

TransCAD 5.0, ArcInfo, and other information sources as 
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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described in Appendix B of the 2050 Regional Transportation Plan 

(October, 2011).32

Table 7: Motor Vehicle Emissions Budgets in the San 

Diego 8-Hour Maintenance Plan

Budget 

Year

VOC (tpd, average 

summer weekday)

NOx (tpd, average 

summer weekday)

2020 23 38

2025 21 30

Source: Table 5-3 on page 5-4 of the San Diego 8-hour 

maintenance plan.

The availability of the SIP submission with MVEBs was 

announced for public comment on EPA's Adequacy Web site on 

December 20, 2012, at: 

http://www.epa.gov/otaq/stateresources/transconf/currsips.htm,

which provided a 30-day public comment period. The comment 

period for this notification ended on January 22, 2013, and EPA 

received no comments from the public. On March 11, 2013, EPA 

determined the 2020 and 2025 MVEBs were adequate.33 The new MVEBs

will be effective 15 days after a notice of adequacy is 

published in the Federal Register. After the effective date the 

new MVEBs must be used in future transportation conformity 

determinations for the San Diego 8-hour area.

EPA proposes to approve 2020 and 2025 MVEBs in the San 

Diego 8-hour maintenance plan for transportation conformity 

 

32 See http://www.sandag.org/uploads/2050RTP/F2050rtp_all.pdf

33 See March 11, 2013 letter from Deborah Jordan, Director, Air Division, 

USEPA Region 9, to James Goldstene, Executive Officer, CARB. A notice of 

adequacy will also be published in the Federal Register to notify the public 

that the Agency has found that the MVEBs for ozone for the years 2020 and 

2025 are adequate for transportation conformity purposes.
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purposes in the final rulemaking on CARB’s redesignation request 

for the San Diego 8-hour area. EPA has determined through its 

thorough review of the submitted maintenance plan that the MVEB 

emission targets are consistent with emission control measures 

in the SIP and that the San Diego 8-hour area can maintain 

attainment of the 1997 ozone NAAQS. The details of EPA's 

evaluation of the MVEBs for compliance with the budget adequacy

criteria of 40 CFR 93.118(e) are provided in a separate adequacy 

letter34 included in the docket of this rulemaking. As indicated 

above, the MVEBs must be used in any conformity determination 

made after the adequacy finding on the budgets is effective,

which will be 15 days after the notice of adequacy is published 

in the Federal Register.

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VI. Proposed Action and Request for Public Comment

Under CAA section 110(k)(3), and for the reasons set forth 

above, EPA is proposing to approve CARB's submittal dated 

December 28, 2012 of the Redesignation Request and Maintenance 

Plan for the 1997 National Ozone Standard for San Diego County

(December 2012) as a revision to the California state 

implementation plan (SIP). In connection with the San Diego 8-

 

34 See March 11, 2013 letter in footnote 33 and enclosure titled, 

"Transportation Conformity Adequacy Review,” for Motor Vehicle Emission 

Budgets in San Diego 8-hour maintenance plan.

35 The Federal Register notice announcing the notice of adequacy will be in 

the docket for this rulemaking and on EPA adequacy web page: 

http://www.epa.gov/otaq/stateresources/transconf/reg9sips.htm#ca.
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hour maintenance plan, EPA finds that the maintenance 

demonstration showing how the area will continue to attain the 

1997 8-hour ozone NAAQS for 10 years beyond redesignation (i.e., 

through 2025) and the contingency provisions describing the 

actions that SDAPCD and CARB will take in the event of a future 

monitored violation meet all applicable requirements for 

maintenance plans and related contingency provisions in CAA 

section 175A. EPA is also proposing to approve the motor vehicle 

emissions budgets (MVEBs) in the San Diego 8-hour maintenance 

plan (shown in table 7 of this document) because we find they 

meet the applicable transportation conformity requirements under 

40 CFR 93.118(e).

Second, under CAA section 107(d)(3)(D), we are proposing to 

approve CARB's request, which accompanied the submittal of the 

maintenance plan, to redesignate the San Diego County 8-hour 

ozone nonattainment area to attainment for the 1997 8-hour ozone 

NAAQS. We are doing so based on our conclusion that the area has 

met the five criteria for redesignation under CAA section 

107(d)(3)(E). Our conclusion in this regard is in turn based on 

our proposed determination that the area has attained the 1997 

ozone NAAQS, that relevant portions of the California SIP are 

fully approved, that the improvement in air quality is due to 

permanent and enforceable reductions in emissions, that 
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Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

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California has met all requirements applicable to the San Diego 

8-hour area with respect to section 110 and part D of the CAA, 

and based on our proposed approval as part of this action of the 

San Diego 8-hour maintenance plan.

EPA is soliciting public comments on the issues discussed 

in this document or on other relevant matters. We will accept 

comments from the public on this proposal for the next 30 days. 

We will consider these comments before taking final action.

VII. Statutory and Executive Order Reviews

Under the CAA, redesignation of an area to attainment and 

the accompanying approval of a maintenance plan under section 

107(d)(3)(E) are actions that affect the status of a 

geographical area and do not impose any additional regulatory 

requirements on sources beyond those imposed by State law. 

Redesignation to attainment does not in and of itself create any 

new requirements, but rather results in the applicability of 

requirements contained in the CAA for areas that have been 

redesignated to attainment. Moreover, the Administrator is 

required to approve a SIP submission that complies with the 

provisions of the Act and applicable Federal regulations. 42 

U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA's role is to approve State choices, provided 

that they meet the criteria of the Clean Air Act. Accordingly, 
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these actions merely propose to approve a State plan and 

redesignation request as meeting Federal requirements and do not 

impose additional requirements beyond those by State law. For 

these reasons, these proposed actions:

 Are not a "significant regulatory action” subject to review 

by the Office of Management and Budget under Executive 

Order 12866 (58 FR 51735, October 4, 1993); 

 Do not impose an information collection burden under the 

provisions of the Paperwork Reduction Act (44 U.S.C. 3501 

et seq.);

 Are certified as not having a significant economic impact 

on a substantial number of small entities under the 

Regulatory Flexibility Act (5 U.S.C. 601 et seq.); 

 Do not contain any unfunded mandate or significantly or 

uniquely affect small governments, as described in the 

Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);

 Do not have Federalism implications as specified in 

Executive Order 13132 (64 FR 43255, August 10, 1999);

 Are not an economically significant regulatory action based 

on health or safety risks subject to Executive Order 13045 

(62 FR 19885, April 23, 1997);

 Are not a significant regulatory action subject to 

Executive Order 13211 (66 FR 28355, May 22, 2001); 
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 Are not subject to requirements of Section 12(d) of the 

National Technology Transfer and Advancement Act of 1995 

(15 U.S.C. 272 note) because application of those 

requirements would be inconsistent with the CAA; and 

 Do not provide EPA with the discretionary authority to 

address disproportionate human health or environmental 

effects with practical, appropriate, and legally 

permissible methods under Executive Order 12898 (59 FR 

7629, February 16, 1994).

In addition, this proposed rule does not have Tribal 

implications as specified by Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is not approved to apply in 

Indian country located in the State, and EPA notes that it will 

not impose substantial direct costs on Tribal governments or 

preempt Tribal law. Nonetheless, in accordance with EPA’s 2011 

Policy on Consultation and Coordination with Tribes, EPA has 

notified Tribes located within the San Diego County 8-hour ozone 

nonattainment.

List of Subjects

40 CFR Part 52

Environmental protection, Air pollution control, 

Intergovernmental relations, Nitrogen dioxide, Ozone, Reporting 

and recordkeeping requirements, Volatile organic compounds.
This document is a prepublication version signed by EPA Regional 

Administrator Jared Blumenfeld on March 14, 2013. We have taken steps to 

ensure the accuracy of this version, but it is not the official version.

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40 CFR Part 81

Environmental protection, Air pollution control, National 

parks, Wilderness areas.

____________________ ________________________

Dated: Jared Blumenfeld

Regional Administrator,

Region IX.