UNITED STATES ENVIRONMENTAL PROTECTION AGENC Y WASHINGTON, D.C. 20460

The Honorable Rick Snyder Governor of Michigan P.O. Box 30013 Lansing , Michigan 48909 Dear Governor Snyder: 

## 1£1 8 2014
THE AD-MINISTRATOR

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 (J.lg/m3) to 12.0 J.lg/m3

. Thousands of scientifi c studies have linked exposure to these tiny particles-approximately 1130th the size of a human hair-with serious human health problems including pr emature 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 staffhave shared with the EPA throughout this process to assess fine particle poll ution levels in communities across your state and the impact ofemission 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 Michigan violates the 2012 standard or contributes to a nearby violation ofthe standard. As a resu lt, the EPA is designating all of Michigan "unclass ifiable/attainment." Becau se 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 like 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 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.

Internet Address (URL) • http ://www.epa

.gov Recycled/Recyclable • Printed w i lh Vegetable Oil Based Inks on 100% Postconsumer, Process Ch lorine Free Recycled PaperTogether, we have made cons i derab l e progress t o r educe fine particle po ll ution. Nationwide, monitored leve l s of fine particle po ll ution fell 34 percent since 2000 when we first began nationwide monitor i ng

for particles of this size. I am confiden t this progress w ill accelerate as toget h er we continue t o work towards our shared goa l of clean a i r. F or additional i nformation about these designations , p lease visit o u r webs i te at: www.epa.gov/ p m d e s ignat i o ns . If you have q u es t ions or co n ce rn s , p l ease contac t me or your s taff may contact Mark Rupp , Deputy Associa t e Admi n istrator for Intergovernmental Relations , at ru p p.mark@epa.g ov or a t (202) 564 - 7178.