UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

The Honorable C. L. "Butch" Otter 

Governor of Idaho 

State Capitol, P.O. Box 83720 

Boise, Idaho 83720 

Dear Governor Otter: 

THE ADMINISTRATOR 

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 of the standard. 

On December 14, 2012, the EPA strengthened the annual, health-based fine particle standard from 15 .0 

micrograms per cubic meter (~g/m ) to 12.0 ~-tg/m . Thousands of scientific studies have linked exposure 

to these tiny partieles- approximately 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 admissions 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 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 most areas in your state meet the 2012 

annual fine particle standard. As a result, 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 meet the standard no later than 2021. As required by the Clean Air Act, those 

actions may include stricter controls on industrial facilities and additional planning requirements for 

transportation-related sources. The enclosed table lists the areas, and counties within them, that the EPA 

is designating nonattainment. 

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 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. 

Internet Address (UAL) • http:l/www.epa.gov 

Recycted/Recyclable • Printed wilh Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper 
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. 

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 continue as we work together 

towards our shared goal of clean air. For additional information about these designations, please visit 

our website at: ww,v.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((i),epa.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