UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8

Ref: 8P-AR

The Honorable Matthew H. Mead Governor ofWyoming State Capitol Cheyenne, Wyoming 82002

Dear Governor Mead: 1595 Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08



## AUG 1

## 9 2014

Thank you for your recommendations dated December 13, 2013 ofair quality designations for the 2012 revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard (NAAQS) throughout Wyoming. I appreciate the information Wyoming shared withthe U.S. Environmental Protection Agency as we move forward to improve PM2.s air quality. This letter is to notify you ofthe EPA'spreliminaryresponse to Wyoming's recommendations and to inform you ofour approach for completing the initial area designations for the 2012 revised primary annual PM2.s standard.

On December 14, 2012, the EPA promulgated a revised primary annual PM2.s NAAQS (78 FR 3086, January 15, 2013). In that action, the EPArevised the primary annual PM2.s standard, strengthening it from 15.0 micrograms per cubic meter (!lg/m3) to 12.0 !lg/m3; retained the existing 24-hourPM2.s standard at 35 !lglm3; retained the existing 24-hourPM10 (coarse particle) standard at 150 !lg/m3; and retained the current suite ofsecondary PM standards. The EPA revised the primary annual PM2.s standard based on an integrated assessment ofan extensive body ofnew scientific evidence, which substantially strengthens ourbody ofknowledgeregardingPM2.s-related health effects. The revised primary annual PM2.s standard willprovide increasedprotection for children, older adults, persons with pre-existing heart and lung disease, and other at-riskpopulations against an array ofPM2.s-related adverse health effects, including premature mortality, increased hospital admissions and emergency department visits, and development and exacerbation ofchronic respiratory disease.

History shows us that betterhealth and cleaner air go hand-in-hand with economic growth. Working closely with the states and tribes, the EPA is implementing the standards using a commonsense approach that improves air quality and minimizes the burden on state, local, and tribal governments. As partof this routine process, the EPA is working withthe states and tribes to identify areas in the country that
meet the standards and those that need to take steps to reduce PM2.s airpollution. Within one year of promulgating a new or revised air quality standard, the Clean AirAct (CAA) requires the governor of each state to submitto the EPA a list ofall areas in the state, with a designationrecommendation for each area. As a first step in implementing the 2012 annual PM2.s standard, governors were to submit their designation recommendations, including appropriate areaboundaries, by December 13, 2013.As required by the CAA, the EPA thenpromulgates designations for all areas across the country. The EPA designates an area as "nonattainment" ifit is violating the 2012 annual PM2.s NAAQS orifit is contributingto a violation ofthe NAAQS in a nearby area. Consistent with designations for previous PM2.s standards, the EPA intends to use a designation category of"unclassifiable/attainment" for areas that are monitoring attainment or do nothave monitors, butfor which the EPAhas reason to believe are likely attainment and are not contributingto nearby violations. Additionally, the EPA intends to designate as "unclassifiable"those areas where the EPA cannot determine based on available information whetherthe area is meeting the NAAQS orwhere EPA has not determined that the area contributes to a nearby violation. At this time, the EPA is proceeding with intended initial area designations using quality-assured, certified air quality monitoring data from 2011 to 2013.

We have consideredthe annual PM2.s designation recommendations submittedby Wyoming on December 13, 2013, and have reviewed the relevant technical information, including 2011-2013 air quality data. These data do not indicate any violation ofthe 2012 annual PM2.s NAAQS inWyoming or contributionto any nearby area. Accordingly, the EPA intends to designate the entire state ofWyoming

as unclassifiable/attainment.

The EPA will make its preliminary designation decisions and supporting documentation available to the general public for review and comment. We will be announcing a 30-daypublic commentperiod shortly in the FederalRegister. After consideringthe additional information we receive, the EPA plans to promulgate final annual PM2.s designations in December of2014.

The EPA is committedto working with the states and tribes to share the responsibility ofreducing PM2.s air pollution. Current and upcoming federal standards and safeguards- including pollutionreduction rules for powerplants, vehicles, and fuels

- will ensure steady progress to reduce PM2.s-forming pollution and will protect public health in communities across the country. We look forward to a continued dialogue withyou and your staffas we worktogether to implementthe 2012 annual PM2.s standard. Should you have any questions, please do not hesitate to contact me, orhave your staffcontact Crystal Ostigaard ofmy staffat (303) 312-6602 orostigaard.crystal@epa.gov.

Shaun L. Regional Administrator

cc: Todd Parfitt, Director, WDEQ Steven A. Dietrich, Administrator, AQD

Janet G. McCabe, Acting Assistant Administrator for Air and Radiation Stephen D. Page, Director, Office ofAir Quality Planning and Standards