UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION Ill 

1650 Arch Street 

Philadelphia, Pennsylvania 19103-2029 

The Honorable Vincent C. Gray 

Mayor of District of Columbia 

John A. Wilson Building 

1350 Pennsylvania Avenue, N.W. 

Suite 316 

Washington, D.C. 20004 

Dear Mayor Gray: 

AUG t 9 Z014 

Thank you for your recommendations regarding air quality designations for the 2012 

revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard (NAAQS) 

throughout the District of Columbia. I appreciate the information the District of Columbia 

shared with the U.S. Environmental Protection Agency (EPA) as we move forward to improve 

PM2.s air quality. This letter is to notify you of EPA's preliminary response to the District of · 

Columbia's recommendations and to inform you of our approach for completing the initial area 

designations for the 2012 revised primary annual PM2.s standard. 

On December 14, 2012, EPA promulgated a revised primary annual PM2.s NAAQS (78 

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

strengthening it from 15.0 micrograms per cubic meter (J.Lg/m3

) to 12.0 J.Lg/m3; retained the 

existing 24-hour PM2.s standard at 35 J.Lg/m3; retained the existing 24-hour PM10 (coarse particle) 

standard at 150 J.Lg/m3

; and retained the current suite of secondary PM standards. 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.srelated 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 ofPM2.s-related adverse health effects, including premature 

mortality, increased hospital admissions and emergency department visits, and development and 

exacerbation of chronic respiratory disease. 

History shows us that better health and cleaner air go hand-in-hand with economic 

growth. Working closely with the states and tribes, EPA is implementing the standards using a 

commonsense approach that improves air quality and minimizes the burden on state, local, and 

tribal governments. As part of this routine process, EPA is working with the states and tribes to 

identify areas in the country that meet the standards and those that need to take steps to reduce 

PM2.s air pollution. Within one year of promulgating a new or revised air quality standard, the 

Clean Air Act (CAA) requires the Mayor of the District of Columbia and the Governor of each 

state to submit to EPA a list with a designation recommendation for each area. As a first step in 

implementing the 20 12 annual PM2.s standard, the Mayor of the District 

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of Columbia and the Governors were required to submit their designation recommendations, 

including appropriate area boundaries, by December 13, 2013. 

As required by the CAA, EPA then promulgates designations for all areas across the 

country. 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, EPA intends to use a designation category of 

"unclassifiable/attainment" for areas that are monitoring attainment or do not have monitors, but 

for which EPA has reason to believe are likely attainment and are not contributing to nearby 

violations. Additionally, EPA intends to designate as "unclassifiable" those areas where 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, EPA 

is proceeding with intended initial area designations using quality-assured, certified air quality 

monitoring data from 2011 to 2013. 

We have considered the annual PM2.s designation recommendations submitted by the 

District of Columbia and have reviewed the relevant technical information, including 2011-2013 

air quality data. These data do not indicate any violation of the 2012 annual PM2.s NAAQS in 

the District of Columbia or contribution to any nearby area. Accordingly, EPA intends to 

designate the entire District of Columbia as unclassifiable/attainment. 

EPA will make its preliminary designation decisions 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, EPA plans to promulgate final annual PM2.s designations in December of2014. 

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 standard. Should you have any questions, please do not 

hesitate to contact me, or have_ your staff contact Ms. Arnie Howell, EPA's District of Columbia 

Liaison, at (215) 814-5722 or howell.amie@epa.gov~ 

cc: Honorable Keith A. Anderson, Director 

District Department of the Environment 

Cecily Beall, Associate Director 

Regional Administrator 

Air Quality Division, District Department of the Environment