UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

The Honorable Jeremiah W. (Jay) Nixon 

Governor of Missouri 

P.O. Box 720 

Jefferson City, Missouri 65102 

Dear Governor Nixon: 

m:c 1 a 2014 

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 (llg/m3) to 12.0 llg/m3. Thousands of scientific studi es have linked exposure 

to these tiny particles- approximately 1/30th 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. 

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 most areas within Missouri do not violate 

the 2012 standard or contribute to a nearby violation of the standard. As a result, consistent with most of 

your area recommendations, the EPA is designating most of the state "unclassifiable/attainment." 

As we have been discussing with your staff, the EPA identified data quality issues earlier this year that 

invalidated tine particle pollution monitoring data for the state of Illinois. Because of these data issues, 

the EPA cannot detennine at this time whether the Illinois portion of the St. Louis, MO-IL area is 

meeting the standard. As a result, even though the monitors in the Missouri portion ofthe St. Louis, 

MO-IL area are showing attainment, the EPA does not have sufficient information to determine whether 

these Missouri counties do or do not contribute to a nearby violation in Illinois. Along with the state of 

Illinois, the EPA is designating the Missouri counties in that area "unclassifiable." The enclosed table 

lists the area and counties in Missouri that the EPA is designating unclassifiable. The EPA will work 

closely with Illinois to ensure that identified problems with air quality monitoring data are corrected. 

The agency intends to reassess levels of fine particle pollution in the St. Louis, MO-IL area once 

sufficient complete air monitoring data are available. 

Internet Address (URL) • hllp://www.epa.gov 

Recycled/Recyclable • Printed with Vegetable Ott Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper 
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. 

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 tine 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: w·w,.v.epa. gm /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.markrmepa.gov or at (202) 564-7178 . . 

Enclosure 
Enclosure- Initial Unclassifiable Area Designations for the 2012 Annual Fine Particle Standard, 

Missouri 

Statefferritory Area Name 2014 EPA Designated 

Unclassifiable Counties 

St. Louis, MO 

St. Louis City, MO 

MO St. Louis, MO-IL St. Charles, MO 

Jefferson, MO 

Franklin, MO