UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

The Honorable Vincent C. Gray Mayor of the District of Columbia 1350 Pennsylvania Avenue NW, Suite 316 Washington, D.C. 20004 Dear Mayor Gray: THE ADMINISTRATOR

I am writing to summarize the U.S
. Environmental Protection Agency's recent action to address fine particle pollution in the District of Columbia. As required by the Clean Air Act, the EPA has determined which areas are meeting the national ambient air quality standards for fine particl e pollution and which areas must take steps to reduce emissions that contribute to violations of the standard. On December 14,2012, the EPA strengthened the annual, health-based fine particle standard from 15.0 micrograms per cubic meter (f..lg/m3) to 12.0 f..1g/m 3

. Thousands of scientific studies have linked exposure to these tiny particles-a pproximately 1/30th the size ofa human hair-with serious human health problems including premature death in people with heart and lung disease, nonfatal heart attacks, and increased hospital admissions and doctor and emergency room visits for respiratory and cardiovascular disease. I appreciate the information you and your staff have shared with the EPA throughout this process to assess fine particle pollution levels in communities across the city and the impact of emission sources that could be contributing to unhealthy air. After considering your recommendations, reviewing the most recent certified fine particle air quality data for the city and evaluating factors to assess contribution to nearby levels offine particle pollution, I have determined that no area within the district violates the 2012 standard or contributes to a nearby violation ofthe standard. As a result, the EPA is designating all of the district " unclassifiable/attainment." Because air quality monitoring for 2014 is nearly complete, if a state or tribe requests it, the EPA will evaluate the status of an area based on its annual fine particle monitoring data for 2012

-2014. If you would li ke the EPA to re-evaluate any areas within your city, please submit to the EPA, complete, quality

-assured and certified air quality data for 2014 by February 27, 2015
. The EPA shares responsibility with the states and tribes for managing particle pollution levels. Efforts by states and tribes to attain the 1997 and 2006 fine particle pollution standards are already working to reduce unhealthy levels of fine particle pollution. In addition, current and upcoming federal standards and safeguards, including pollution reduction rules for power plants, vehicles and fuels will assure steady reductions of fine particle pollution and will protect public health in communities across the country.

lntemet Address (URL) • http ://www

.epa .gov Recycled/Recyclable • Pr i n ted w ith Vegetab l e Oil Based Inks on 100% Postconsumer, Process Chlori ne Free Recyc l ed PaperTogether, we have made considerable progress to reduce fine particle pollution. Nat ion w id e , monitored leve l s of fine particle pollution fell 34 percent since 2000 when we first began nationwide monitor i ng

for particles of this size. I am confident this progress will accelerate as together we continue to work towards our shared goa l of clean a i r . For additional**i~format on**  about these designations, please visit our website at: www.epa.gov / pmdesignations . '

If you have questions or concerns , please contact me or your staff may contact Mark Rupp, Deputy Associate Administrator for Intergovernmental Relations , at rupp.mark@epa . gov or at (202) 564 - 7178. Sincerely,