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

The Honorable C. L. "B utch" Otter Governor of Idaho State Capitol, P.O. Box 83720 Boise, Ida ho 83720 Dear Governor Otter: THE ADMINISTRATOR

I am writing to summar ize the U.S. Environmental Protection Agency 's recent action to address fi ne 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 of the standard. On December 14 , 2012, the EPA strengthened th e annual, health-based fine particle standa rd from 15 .0 micrograms per cubic meter

**(~g/m )**  to 1 2 .0

**~-tg /m**  **.** Thousands of scientific s tudi es have linked exposure to these tiny partieles
- app r oximately l /30th 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 admi ss ions and doctor and emergency room visits for respiratory and cardiovascular disease. 

## r appreciate the information you and your staff have shared with the EPA throughout this process to assess fine particl e pollu ti on levels in communities across your state and the impact of emission sou rce s that could be contributing to unhealthy air. After considering your recommendations, reviewing the mo st recent certified fine partic l e air quality data for your state and evaluating factors to assess co ntribution to nearby levels of fine particle pollution, I have determined that most areas in your sta te meet the 2012 annual fine particle standard. As a res ult, the EPA is designating the majority of the state " unclassifiable/attainment. " Also, one area in your state does not meet the 2012 annual fine particle standard. The EPA is designating this area "nonattainment. " Nonattainment areas will be required to take action to reduce fine particle pollution and me et the standard no later than 2021. As requi red by the Clean Air Act, those actions may include stricter controls on industrial fac ili ties and add iti onal planning requirements for transportation-related sources. The enclosed table li sts the areas, and counties within them, that the EPA is designating nonattainm ent. Becau se air quality monitoring for 2014 is nearly complete , if a state or tribe requests it, the EPA will eval uate 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 w ithin your state, please submit to the EPA, complete , quality-assured and certified air quality data for 2014 by February 27,2015.
I nternet Address (UAL) • http : l/www
.epa .gov Recycted/R ecycla b le • Printed wilh Vegetable Oil Based Inks on 100% Postconsumer, Process Chlor i ne Free Recyc l ed PaperThe EPA shares responsibility with the states and tribes for managing particle pollution levels. Efforts by stat e s and tribes to attain the 1997 and 2006 fine particle pollu t i on standards are a l ready working to reduce unhealthy levels o f fin e 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 part icl e pollution and will protect public health in communities across the country. Together, we have made considerable progress to reduce fine particle pollution. Nationwide , monitored levels of fine particle pollution have fallen 34 percent since 2000 when we first began nationwide monitoring for particles of this size . I am confident this progress will cont i nue as we work together towards our shared goal of clean air. For additional information about these designations, please visit our website at: ww,v . e p a.gov/ p mdesignat i ons .

If you have questions or concerns, please contact me or your staff may contact Mark Rupp, Deputy Associate Administrator for Intergovernmental Relations, at ru pp. mark( (i ),e p a . gov or at (202) 564-7178. Sincerely,**naMcC ~**  Enclosure

### Enclosure
- Initial Nonattainment Area Designations for the 2012 Annual Fine Particle Standard, Idaho
State Area Name 2014 EPA Designated Nonattainment Counties ID West Silver Valley , 

### 10 Shoshone, ID (p) (p) partial county