UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASH I NGTON, D.C. 20460

The Honorable Jack Markell Governor of Delaware 

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150 Martin Luther King Jr. Boulevard South, 2nd Floor Dover, Delaware 19901 Dear Governor Markell: THE ADM I NISTRATOR

I am writing to summarize the U.S. Environmental Protection Agency 's recent action to address fine particle pollution in your state. As required by the Clean Air Act, the EPA has determined which areas are meeting the national ambient air quality standards for fine particle pollution and which areas must take steps to reduce emissions that contribute to violations ofthe standard. On December 14,2012, the EPA strengthened the annual, health-based fine particle standard from 15.0 micrograms per cubic meter (Jlg/m3 ) to 12.0 Jlglm3

. Thousands ofscientific studies have linked exposure to these tiny particles-approximately ! /3 0th the size of a 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 your state 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 your state and evaluating factors to assess contribution to nearby levels of fine particle pollution, I have determined that no area within Delaware violates the 20 12 standard or contributes to a nearby violation of the standard. As a result, the EPA is designating all of Delaware "unclassifiableiattainment." 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 2012-20 14. If you would li ke the EPA to re-evaluate any areas within your state, please submit to the EPA, complete, quality-assured and certified air quality data for 2014 by February 27,2015. The EPA shares r esponsibility with the states and tribes for managing particle pollution levels. Efforts by states and tribes to attain the 1997 and 2006 fi ne particle pollution standards are already working to reduce unhealthy levels of fine particle pollution. In addition, current and upcoming federal standard s 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.

Internet Address {URL) • http : J/www

.epa.gov Recycled/Recyclab l e • Pri nted w i th Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recyc l ed PaperTogether, we have made considerab l e progress to reduce fine part icl e pollut i on. Nationwide, monitored le vels of fine particle pollution fell 34 percent since 2000 when we first began nationwide monitoring for particles of this size. I am confident th is progress w ill accelerate as together we continue to work towards our shared goal of clean air. For additional information about these designat i ons, please visit our website at: www.epa.go v/ pmdesignat i ons .

If you have quest ion s or concerns , please contact me or your staff may contact Mark Rupp , Deputy Associate Administrator for Intergo v ernmental Relations , at rupp . mark @ epa.gov or at (202) 564-7178.