UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105-3901 

The Honorable Edmund G. Brown, Jr. 

State Capitol Building, Suite 1173 

Sacramento, California 95814 

Dear Governor Brown: 

AUG 1 9 2014 

OFFICE OF THE 

REGIONAL ADMINISTRATOR 

Thank you for your recommendations, dated Novemb~r 25,2013 and July 2, 2014, of air quality 

designations for the 2012 annual fine particle National Ambient Air Quality Standard (2012 annual 

PM2.s NAAQS) throughout California. This letter is to notify you of the U.S. Environmental Protection 

Agency's (EPA) preliminary response to California's recommendations and to inform you of our 

approach for completing the initial area designations for the 2012 annual PM2.s NAAQS. 

The EPA agrees with your November 25, 2013 and July 2, 2014 recommendations. After considering 

California's annual PM2.s designation recommendations and other relevant technical information, 

including 2011-2013 air quality data; the EPA agrees with California's recommended designations and 

boundaries and intends to designate the Portola Valley portion of Plumas County, the San Joaquin 

Valley, Los Angeles-South Coast, and a portion of Imperial County as nonattainment. A Technical 

Support Document, which provides a detailed analysis to support our preliminary decisions, is enclosed 

and is available on the EPA's website at: http://www.epa.gov/pmdesignations/2012standards/state.htm. 

The EPA intends to designate all other areas of the state as unclassifiable/attainment, except for the 

Pechanga Band of Luisefio Mission Indians, who recommended "unclassifiable" for their portion of 

Indian country, which the EPA intends to designate as "unclassifiable." The EPA will continue to work 

with both state and tribal officials regarding the appropriate boundaries for the areas in California. If 

California has additional information for the EPA to consider, please submit it to us by October 29, 

2014. 

The EPA will make its preliminary designation dec,isions and supporting documentation available to the 

general public for review and comment. We will be announcing a 30-day public comment period shortly 

in the Federal Register. After considering the additional information we receive, the EPA plans to 

promulgate final annual PM2.s designations in December of2014. 

As background, on December 14, 2012, the EPA promulgated a revised primary a1mual PM2.s NAAQS 

(78 FR 3086, January 15, 2013). In that action, the EPA revised the primary annual PM2.s standard, 

strengthening it from 15.0 micrograms per cubic meter (11g/m3

) to 12.0 11g/m3

; retained the existing 24-

hour PM2.s standard at 35 11g/m3

; retained the existing 24-hour PM10 (coarse particle) standard at 150 

11g/m3

; and retained the current suite of secondary PM standards. The EPA revised the primary annual 

PM2.s standard based on an integrated assessment of an extensive body of new scientific evidence, which 

substantially strengthens our body of knowledge regarding PM2.s-related health effects. The revised 

primary annual PM2.s standard will provide increased protection for children, older adults, persons with 

pre-existing heart and lung disease, and other at-risk populations against an array ofPM2s-related 

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adverse health effects, including premature mortality, increased hospital admissions and emergency 

department visits, and development and exacerbation of chronic respiratory disease. 

The EPA designates an area as "nonattainment" if it is violating the 2012 annual PM2.s NAAQS or if it 

is contributing to a violation of the NAAQS in a nearby area. Consistent with designations for previous 

PM2.s standards, the EPA intends to use a designation category of "unclassifiable/attainment" for areas 

that are monitoring attainment or do not have monitors, and that the EPA has reason to believe are likely 

attainment and are not contributing to nearby violations. Additionally, the EPA intends to designate as 

"unclassifiable" those areas where the EPA cannot determine based on available information whether 

the area is meeting the NAAQS or where EPA has not determined that the area contributes to a nearby 

violation. At this time, the EPA is proceeding with intended initial area designations using qualityassured, certified air quality monitoring data from 2011 to 2013. 

The EPA is committed to working with the states and tribes to share the responsibility of reducing PM2.s 

air pollution. Current and upcoming federal standards and safeguards- including pollution reduction 

rules for power plants, vehicles, and fuels - will ensure steady progress to reduce PM2.s-forming 

pollution and will protect public health in communities across the country. We look forward to a 

continued dialogue with you and your staff as we work together to implement the 2012 annual PM2.s 

NAAQS. Should you have any questions, please contact me, or have your staff contact Deborah Jordan 

of my staff at 415-947-8715, or jordan.deborah@epa.gov. 

Sincerely, 

Enclosure 

cc: Matthew Rodriguez, Secretary, California Environmental Protection Agency 

Mary Nichols, Chairman, California Air Resources Board 

Richard Corey, Executive Officer, California Air Resources Board 

Mark A. Macarro, Chairman, Pechanga Band of Luisefio Mission Indians 

cc: (via email without enclosure) 

Barry Wallerstein, D.Env., Executive Officer, South Coast Air Quality Management District 

Seyed Sadredin, Air Pollution Control Officer, San Joaquin Valley Air Pollution Control District 

Brad Poiriez, Air Pollution Control Officer, Imperial County Air Pollution Control District 

Gretchen Bennitt, Air Pollution Control Officer, Northern Sierra Air Quality Management 

District