The Honorable Michael R. Pence 

Governor of Indiana 

100 North Senate A venue 

Indianapolis, Indiana 46204 

Dear Governor Pence: 

Thank you for your recommendation(s) dated December 12, 2013, and addendum dated May 12, 

2014, of air quality designations for the 2012 revised primary annual fine particle (PM2.s) 

National Ambient Air Quality Standard (NAAQS) throughout Indiana. I appreciate the 

information Indiana shared with the U.S. Environmental Protection Agency as we move forward 

to improve PM2.s air quality. This letter is to notifY you of EPA's preliminary response to 

Indiana's recommendation and to inform you of our approach for completing the initial area 

designations for the 2012 revised primary annual PM2s standard. 

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

January 15, 2013). In that action, EPA revised the primary annual PM2.s standard, strengthening 

it from 15.0 micrograms per cubic meter ()lg/m3) to 12.0 11g/m3; retained the existing 24-hour 

PM2.s standard at 35 11g/m3; retained the existing 24-hour PM to (coarse particle) standard at 150 

11g/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 ofPM2.s-related adverse health effects, including prematme 

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 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 promulgation of 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 2012 annual 

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

appropriate area boundaries, by December 13, 2013. 

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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 initial area designations using quality-assured, certified air quality monitoring 

data from 2011 to 2013. 

EPA has reviewed Indiana's December 12, 2013 and May 12, 2014 designation 

recommendations and other relevant technical information, including 2011-2013 air quality data, 

and EPA intends to modify Indiana's recommended area designations for the Louisville, KY -IN 

and the Chicago, IL-IN areas. The intended Louisville, KY-IN nonattainment area reflects 

violation of the 2012 annual PM2.s NAAQS in Clark County, Indiana. The 2011-2013 data do 

not indicate any violation of the 2012 annual PM2s NAAQS in Northwest Indiana. However, a 

recent EPA-conducted technical systems audit of Illinois' monitoring program revealed data 

quality issues in the Chicago area and elsewhere in Illinois which affect the designations for 

Lake and Porter Counties in Indiana. Because many if not all of the recent PM2.s monitoring data 

in Illinois must be considered invalid, EPA cannot determine whether the counties in the Illinois 

portion of the Chicago area (and elsewhere in Illinois) are meeting or not meeting the NAAQS or 

whether cmmties nearby to those Illinois counties, including two counties in Northwest Indiana, 

contribute to a nearby violation. Accordingly, EPA intends to modify Indiana's recommended 

area designation and designate Lake and Pmier counties as unclassitlable. Technical Support 

Documents, which provide additional detail regarding our preliminary decisions, are enclosed 

and are also available on EPA's website at 

EPA intends to designate all other 

areas of the state as unclassifiable/attainment. EPA will continue to work with state officials 

regarding the appropriate boundaries for the areas in Indiana. lf Indiana has additional 

infonnation for EPA to consider, please submit it to us by October 29,2014. 

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

general public for review and comment. We will be am1ouncing a 30-day public comment 

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

EPA plans to promulgate final annual PM2.s designations in December of 2014. 

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 

PM2s-forming pollution and will protect public health in communities across the country. We 
< 

Susan Hedman 

Regional Administrator Enclosures 

cc: Tom Easterly 

Commissioner, Indiana Department of Environmental Management 

Keith Baugues 

Assistant Commissioner, Office of Air Quality 

Indiana Department of Environn1ental Management