The Honorable Mark Dayton 

Governor of Minnesota 

116 V cterans Service Building 

20 West 12th Street 

St. Paul, Minnesota 55155 

Dear Governor Dayton: 

Thank you for your recommendations dated December 6, 2013 , of air quality designations for the 

2012 revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard 

(NAAQS) throughout Minnesota. I appreciate the information Minnesota shared with the U.S. 

Envirmm1ental Protection Agency as we move forward to improve PM2.s air quality. This letter 

is to notify you ofEPA's intended response to Minnesota's recommendations and to inform you 

of our approach for completing the initial area designations for the 2012 revised primary annual 

PM2.s standard. 

On December 14, 2012, EPA promulgated a revised primary annual PM2.s NAAQS (78 FR 3086, 

.Tanuary 15, 20 13). In that action, EPA revised the primary annual PM2.:i standard, strengthening 

it from 15.0 micrograms per cubic meter (J..Lg/m3) to 12.0 J..Lg/m3; retained the existing 24-hour 

PM2.s standard at 35 flg/m3; retained the existing 24-hour PM10 (coarse particle) standard at 150 

J..Lg/m3; and retained the current suite of secondary PM standards. EPA revised the primary annual 

PM2.s standard based on an integrated assessment of an extensive body of new scientific 

evidence, which substantially strengthens our body of knowledge regarding PM2.s-related health 

effects. The revised primary annual PM2.s standard will provide increased protection for 

children, older adults, persons with pre-existing heart and lung disease, and other at-risk 

populations against an array of PM2.s-related adverse health effects, including premature 

mortality, increased hospital admissions and emergency department visits, and development and 

exacerbation of chronic respiratory disease. 

History shows us that better health and cleaner air go hand-in-hand with economic growth. 

Working closely with the states and tribes, EPA is implementing the standards using a 

commonsense approach that improves air quality and minimizes the burden on state, local, and 

tribal governments. As part of this routine process, EPA is working with the states and tribes to 

identify areas in the country that meet the standards and those that need to take steps to reduce 

PM2.s air pollution. Within one year of promulgating a new or revised air quality standard, the 

Clean Air Act requires the Governor of each state to submit to EPA a list of all areas in the state, 

with a designation recommendation for each area. As a first step in implementing the 20 12 

armual PM2.s standard, Governors were to submit their designation recommendations, including 

appropriate area boundaries, by December 13, 2013. 

Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (100% Post-Consumer) 
cannot determine based on available information whether the area is meeting the NAAQS or 

where EPA has not determined that the area contributes to a nearby violation. At this time, EPA 

is proceeding with intended initial area designations using quality-assured, certified air quality 

monitoring data from 2011 to 2013. 

EPA has reviewed Minnesota's December 6, 20 13, annual PM2.s designation recommendations 

and other relevant technical information, including 2011- 2013 air quality data. These data do 

not indicate any violation of the 2012 annual PM2.s NAAQS in Minnesota or contribution to any 

nearby area. Accordingly, EPA intends to designate the entire state of Minnesota as 

unclassifiable/attainment. 

EPA will make its proposed designation decisions and supporting documentation available to the 

general public for review and comment. We will be announcing a 30-day public comment 

period shortly in the Federal Register. After considering the additional information we receive, 

EPA plans to promulgate final armual PM2.s designations in December of2014. 

EPA is committed to working with the states and tribes to share the responsibility of reducing 

PM2.s air pollution. Current and upcoming federal standards and safeguards - including 

pollution reduction rules for power plants, vehicles, and fuels - will ensure steady progress to 

reduce PM2.5-forming pollution and will protect public health in communities across the country. 

We look forward to a continued dialogue with you and your staff as we work together to 

implement the 2012 annual PM2.s standard. If you any questions, please contact me or your staff 

may contact Ronna Beckmann or Eileen Deamer, the Region 5 Intergovernmental Liaisons, 

at (312) 886-3000. 

Sincerely, Susan Hedman 

Regional Administrator 

cc: John Line Stine 

Commissioner 

Minnesota Pollution Control Agency 

David Thornton 

Assistant Commissioner 

Minnesota Pollution Control Agency