State of California

Staff Review

of the

Supplemental Document for the 

San Joaquin 24-Hour PM2.5 Standard 

State Implementation Plan

Release Date: September 22, 2014

Scheduled for Consideration: October 24, 2014

California Environmental Protection Agency

AIR RESOURCES BOARD
This document has been reviewed by the staff of the California Air Resources Board 

and approved for publication. Approval does not signify that the contents necessarily 

reflect the views and policies of the Air Resources Board, nor does the mention of trade 

names or commercial products constitute endorsement or recommendation for use.

Electronic copies from this document are available for download from the Air Resources 

Board’s Internet site at: http://www.arb.ca.gov/planning/sip/planarea/sanjqnvllysip.htm.

In addition, written copies may be obtained from the Public Information Office, Air 

Resources Board, 1001 I Street, 1st Floor, Visitors and Environmental Services Center, 

Sacramento, California 95814, (916) 322-2990.

For individuals with sensory disabilities, this document is available in Braille, large print, 

audiocassette or computer disk. Please contact ARB's Disability Coordinator at 

(916) 323-4916 by voice or through the California Relay Services at 711, to place your 

request for disability services. If you are a person with limited English and would like to 

request interpreter services, please contact ARB's Bilingual Manager at 

(916) 323-7053.

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Supplemental Document for the San Joaquin Valley 

24-hour PM2.5 Standard State Implementation Plan 

This Report documents the Air Resources Board staff’s review of the Supplemental 

Document: Clean Air Act Subpart 4: The 2012 PM2.5 Plan for the 2006 PM2.5 Standard 

and District Rule 2201 (New and Modified Stationary Source Review) (Supplemental 

Document) adopted by the San Joaquin Valley Air Pollution Control District (District). 

The Supplemental Document demonstrates compliance with the requirements under 

Subpart 4 of the Clean Air Act (Act) for the 24-hour PM2.5 standard and provides the 

information U.S. Environmental Protection Agency (U.S. EPA) needs to approve the

San Joaquin Valley 24-hour PM2.5 SIP under Subpart 4 of the Act.

I. BACKGROUND

In December 2012, the District adopted a State Implementation Plan (SIP) for the 

35 μg/m3 24-hour PM2.5 standard (2012 PM2.5 Plan1

). The 2012 PM2.5 Plan was 

developed to meet requirements of the U.S. EPA 2007 Fine Particle Implementation 

Rule2 (2007 Implementation Rule) based on Subpart 1 provisions of the Act. In 

January 2013, the Air Resources Board (ARB or Board) approved3 the 2012 PM2.5 

Plan. 

In the time between the 2012 PM2.5 Plan adoption by the District in December 2012 

and the ARB hearing in January 2013, the D.C. Circuit Court determined that U.S. EPA

erred in solely developing its implementation rule for PM2.5 under the Subpart 1 general 

provisions of the Act without considering the more specific particulate matter provisions 

in Subpart 4. The Court remanded the rule back to U.S. EPA to address the Subpart 4

provisions. During the January 2013 ARB hearing, the Board determined that it was 

appropriate to approve the 2012 PM2.5 Plan at that time and provide any necessary 

supplemental information once U.S. EPA provided guidance in response to the 

D.C. Circuit Court decision. 

In accordance with Subpart 4 provisions of the Act, in June 2014, U.S. EPA classified 

the San Joaquin Valley (SJV) as a moderate nonattainment area4 for the 35 μg/m3

1 SJVUAPCD, 2012 PM2.5 Plan. http://www.valleyair.org/Air_Quality_Plans/PM25Plans2012.htm 2 U.S. EPA, Clean Air Fine Particle Implementation Rule; Final Rule. (20586 – 20667) April 25, 2007. 

http://www.epa.gov/fedrgstr/EPA-AIR/2007/April/Day-25/a6347.pdf 3 ARB, San Joaquin Valley PM2.5 State Implementation Plan, Resolution 13-2 (January 21, 2013) 

http://www.arb.ca.gov/planning/sip/sjvpm25/FIN%20RESO%2013-2.pdf 4 U.S. EPA, Identification of Nonattainment Classification and Deadlines for

Submission of State Implementation Plan Provisions for the 1997 Fine Particle (PM2.5) National Ambient 

Air Quality Standard (NAAQS) and 2006 PM2.5 NAAQS, 79 FR 105, pp. 31566-31782 (June 2, 2014)

http://www.gpo.gov/fdsys/pkg/FR-2014-06-02/pdf/2014-10395.pdf

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24-hour PM2.5 standard and directed the State to submit a SIP by the end of 2014 that 

meets the moderate area requirements. U.S. EPA directed states to use existing 

guidance for PM10 implementation under Subpart 4 and apply the guidance to the 

PM2.5 standard. 

On September 18, 2014, the District adopted the Supplemental Document5

. The 

Supplemental Document demonstrates that the existing 2012 PM2.5 Plan satisfies 

Subpart 4 requirements for a moderate PM2.5 nonattainment area. The Supplemental 

Document also includes the District’s request that the SJV be classified as a serious 

PM2.5 nonattainment area under Subpart 4 consistent with the attainment 

demonstration in the 2012 PM2.5 Plan. 

II. ADOPTED 2012 PM2.5 PLAN MEETS SUBPART 4 REQUIREMENTS

The Supplemental Document includes a detailed comparison of PM2.5 implementation 

requirements under Subpart 1 and Subpart 4. These requirements are summarized in 

Table 1. Focusing on the requirements that differ between Subparts 4 and 1, the 

Supplemental Document shows how the 2012 PM2.5 Plan adopted by ARB and the 

District also satisfies the Subpart 4 requirements.

• Attainment Date: Under Subpart 1, a non-attainment area has an attainment date 

of five years from the nonattainment designation, which is 2014, and up to 2019 if 

earlier attainment is not practicable. In contrast, per the area classification 

requirements of Subpart 4, the moderate area attainment date is six years after 

designation or 2015, and the serious attainment date is four years later or 2019. 

The photochemical modeling and other technical analyses in the 2012 PM2.5 Plan 

demonstrated that 2019 is the most expeditious date for reaching attainment 

throughout the SJV. This modeling was conducted consistent with U.S EPA 

guidance. The 2012 PM2.5 Plan attainment strategy includes emission reductions, 

to occur each year through 2019, from implementing a combination of ARB and 

District programs including reductions from the State mobile source program. The 

District actions include further strengthening of its wood burning curtailment program 

and additional requirements on commercial cooking operations, to bring the entire 

SJV into attainment by 2019. 

5 SJVAPCD, Supplemental Document: Clean Air Act Subpart 4: The 2012 PM2.5 Plan for the 2006 PM2.5 

Standard and District Rule 2201 (New and Modified Stationary Source Review). September 18, 2014

http://www.valleyair.org/Board_meetings/GB/agenda_minutes/Agenda/2014/September/final/06.pdf

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Table 1. Subpart 1 and Subpart 4 Comparison of 35 ug/m3 24-hour PM2.5 

Standard Implementation 

SIP Component Subpart 1 Subpart 4

Classifications None Moderate Area

Serious Area

Attainment Dates • Five years from designation 

date (December 2014)

• May be extended to up to ten 

years from designation date

(December 2019)

Moderate Area:

• By the end of the sixth year after 

designation (December 2015)

Serious Area:

• By the end of the tenth year after 

designation (December 2019)

• May extend up to five years 

(December 2024)

SIP Submission 

Deadlines 

Three years after designation 

(December 2012)

Moderate Area:

• 18 months after designation

 (December 31, 2014)

Serious Area: 

• 18 months after reclassification

Precursor 

Requirements

• Must address sources of 

directly emitted PM2.5, SOx, 

and NOx.

• Address ammonia or VOC if 

they significantly contribute to 

PM2.5 levels in the area. 

Must address sources of all PM2.5 and 

PM2.5 precursors. 

Level of 

Emission 

Controls

Reasonably Available Control 

Measures (RACM)

• Moderate Area: RACM

• Serious Area: Best Available Control 

Measures

Reasonable 

Further Progress

Linear progress towards 

attainment 

Quantitative milestones to be achieved 

every 3 years 

Permitting 

Program

Major Sources not required to 

control ammonia or VOC, unless 

demonstrated that they contribute

significantly to PM2.5 

concentrations in the area.

Major source is over 100 tons per 

year (tpy). 

Major Sources must control all 

precursors of PM2.5, unless 

demonstrated that such precursors do 

not contribute to levels which exceed 

the standard. 

Moderate Area: Major source is over 

100 tpy.

Serious Area: Major source is over 

70 tpy.

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U.S. EPA can reclassify SJV from moderate to serious if it determines that SJV 

cannot practicably attain by 2015 based on the attainment analysis in the 2012 

PM2.5 Plan. Classifying SJV as a serious area will maintain the current attainment 

date as implementation of the 2012 PM2.5 Plan moves from Subpart 1 to Subpart 4.

• Precursors Requirements: Under Subpart 1, only directly emitted PM2.5, sulfur 

oxides (SOx), and nitrogen oxides (NOx) were presumed significant plan precursors.

Under Subpart 4, states must address all precursors including ammonia and volatile 

organic compounds (VOC). However, states may make a demonstration that a 

precursor is not significant if a significant reduction in emissions does not result in a 

significant decrease in PM2.5 concentrations. 

The role of ammonia and VOC in SJV PM2.5 concentrations is discussed in the 

2012 PM2.5 Plan and summarized in the Supplemental Document. Based on the 

large body of published scientific evidence from research conducted through the 

extensive California Regional Particulate Matter Air Quality Study (CRPAQS) and 

subsequent data analysis and modeling studies, as well as photochemical modeling 

conducted in support of the 2012 PM2.5 Plan, reductions in either ammonia or VOC 

would not significantly advance PM2.5 attainment in the Valley. 

In developing the 2012 PM2.5 Plan, a number of studies and analyses based on 

CRPAQS were evaluated to understand the role of ammonia in the SJV. 

Measurements of chemically speciated PM2.5 show that ammonium nitrate (formed 

in the air from reactions of ammonia and NOx emissions) is a major component of 

PM2.5. Ambient measurements of ammonia, nitric acid, and particulate ammonium

nitrate demonstrate, however that due to the excess of ammonia relative to nitric 

acid (formed from NOx emissions) throughout the SJV, the amount of NOx 

emissions limit the formation of ammonium nitrate. 

The 2012 PM2.5 Plan also evaluated studies to understand the role of VOC in 

secondary organic aerosol and ammonium nitrate formation, including a number of 

photochemical modeling exercises using CRPAQS data. These studies show 

secondary organic aerosols derived from anthropogenic VOC emissions account for 

a very small portion of PM2.5 and indicate that in the SJV, NOx, rather than VOC, is 

the limiting precursor for nitric acid, and subsequent ammonium nitrate formation. 

In addition to these studies, photochemical modeling sensitivity analysis was also 

conducted as part of the 2012 PM2.5 Plan to determine the relative effectiveness of 

emission reductions in PM2.5, NOx, SOx, ammonia, and VOCs. This modeling 

demonstrated in the Bakersfield area, which measures the highest PM2.5 levels in 

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the SJV, NOx and PM2.5 reductions are 10 and 40 times more effective than 

ammonia reductions on a per ton basis. The modeling also indicates that VOC 

reductions have no benefit and may in some case cause a very slight increase in 

PM2.5 concentrations.

Accordingly, the 2012 PM2.5 Plan appropriately includes directly emitted PM2.5, 

SOx and NOx as the significant PM2.5 precursors to control consistent with 

Subpart 4 requirements. 

• Reasonably Available Control Measures (RACM): Under Subpart 1 and 

Subpart 4 for moderate areas, RACM is the required minimum control level. Per 

Subpart 4, RACM must be in place within four years of an area’s nonattainment 

designation. The 2012 PM2.5 Plan includes a thorough analysis focused on PM2.5, 

NOx, and SOx of reasonably available measures adopted by the District and ARB 

over emission sources operating in the SJV. ARB has adopted the most stringent 

control measures in the nation for on-road and off-road mobile sources and the fuels 

that power them. The 2012 PM2.5 Plan RACM analysis compares District rules for 

all stationary and area source with other rules in the country for those sources. The 

RACM analysis shows that the District is implementing RACM for stationary and 

area sources, and many of the adopted rules go beyond RACM. If U.S. EPA 

classifies the SJV as a serious nonattainment area, the required control level will 

become best available control measures (BACM) and a subsequent BACM analysis 

and SIP submittal will be needed. 

• Reasonable Further Progress (RFP): Under Subpart 1, the Plan must 

demonstrate generally linear progress to meet RFP requirements. Under Subpart 4, 

the Plan must include quantitative milestones to be achieved every three years until 

the area is redesignated to attainment and which demonstrate RFP. The 2012 

PM2.5 Plan identifies RFP emission level milestones for 2014 and 2017 that show 

generally linear progress in emission reductions towards attainment in 2019. These 

milestones in the 2012 PM2.5 Plan meet the requirements for quantitative 

milestones required under Subpart 4.

• Contingency Requirements: Per Subpart 1, contingency measures provide 

additional emission reductions in the event a nonattainment area fails to achieve 

either RFP targets or attain the PM2.5 standard by its attainment date. These 

contingency measures are to take effect without any further ARB or District 

regulatory action. The Supplemental Document demonstrates that a larger amount 

of emission reductions from ARB and District regulations are being achieved than 

those needed to meet RFP. This difference in emission reductions is enough to 

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meet the contingency requirements. The 2012 PM2.5 Plan does not include 

contingency for 2015, the moderate area attainment date, because 2015 was not a 

milestone year in a plan that shows attainment in 2019. The 2012 PM2.5 Plan does 

already include the contingency reductions for 2019 which will be required under 

Subpart 4 if U.S. EPA classifies the region as a serious nonattainment area. 

• New Source Review (NSR) Program: U.S. EPA also set a deadline of 

December 31, 2014 for the District to demonstrate their PM2.5 permitting program 

complies with Subpart 4 requirements. To meet the deadline, the Supplemental 

Document describes how the District NSR Rule 2201 satisfies these requirements. 

Subpart 4 requires the control of PM2.5 precursors at major stationary sources 

except when they do not contribute significantly to PM2.5 levels. The 2012 PM2.5 

Plan addresses NOx and SOx as PM2.5 precursors and demonstrates ammonia and 

VOC do not contribute significantly to PM2.5 levels. Consistent with this 

assessment, Rule 2201 treats NOx and SOx as PM2.5 precursors for permitting 

requirements. 

In addition, under Subpart 4 requirements for moderate areas, major sources of 

PM2.5 are defined as those sources with the potential to emit 100 tons per year (tpy) 

or more. Rule 2201 already includes this threshold for PM2.5, plus appropriate 

thresholds for NOx and SOx. 

III. STAFF RECOMMENDATION

The District Supplemental Document: Clean Air Act Subpart 4: The 2012 PM2.5 Plan for 

the 2006 PM2.5 Standard and District Rule 2201 (New and Modified Stationary Source 

Review) demonstrates that the San Joaquin Valley 2012 PM2.5 Plan satisfies 

requirements for a moderate PM2.5 nonattainment area under Subpart 4 of the Act. 

The Supplemental Document also discusses that a serious area classification aligned 

with the attainment date in the 2012 PM2.5 Plan is appropriate. Once submitted to U.S. 

EPA, this Supplemental Document should enable U.S. EPA to approve the 2012 PM2.5 

Plan as meeting the Subpart 4 moderate area requirements. 

Staff recommends that the Board approve the District Supplemental Document: Clean 

Air Act Subpart 4: The 2012 PM2.5 Plan for the 2006 PM2.5 Standard and District Rule 

2201 (New and Modified Stationary Source Review) along with the District request to 

classify the SJV as a serious nonattainment area and submit to U.S. EPA as a revision 

to the California SIP.

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