UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8

Ref: 8P-AR

The Honorable John W. Hickenlooper Governor ofColorado 136 State Capitol Denver, Colorado 80203-1792

Dear Governor Hickenlooper: 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://'l!fflW.epa.gov/region08



### A.UG 19 

### 2014

Thank you for your recommendations dated January 27, 2014 ofairquality designations for the 2012 revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard (NAAQS) throughout Colorado. I appreciate the information Colorado 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's preliminaryresponse to Colorado'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.sNAAQS (78 FR 3086, January 15, 2013). In that action, the EPA revised the primary annual PM2.s standard, strengthening it from 15.0 micrograms percubic meter (Jlg/m3) to 12.0 Jlg/m3; retainedthe existing 24-hourPM2.s standard at 35 Jlglm3; retainedthe existing 24-hour PM10 (coarse particle) standard at 150 Jlg/m3; and retained the current suite ofsecondary PM standards. The EPA revised the primary annual PM2.s standard based on an integrated assessment of1:1n extensive body ofnew scientific evidence, which substantially strengthens ourbody ofknowledge 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-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 better health 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 part of this routine process, the EPA is working withthe states and tribes to identify areas in the countrythat
meetthe standards and those that need to take steps to reduce PM2.s airpollution. Within one year of promulgating a neworrevised air quality standard, the Clean Air Act (CAA) requires the governor of each state to submitto the EPA a list ofall 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.As required bythe 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 or ifit 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 not have monitors, but for whichthe 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 meetingthe NAAQS or where EPAhas not determined thatthe area contributes to a nearby violation. Atthis 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 Colorado on January 27, 2014, and have reviewed the relevanttechnical information, including 2011-2013 air quality data. These data do not indicate any violation ofthe 2012 annual PM2.s NAAQS in Colorado or contributionto any nearby area. Accordingly, the EPA intends to designate the entire state ofColorado

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 inDecember of2014.

The EPA is committed to 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 steadyprogress to reduce PM2.s-forming pollution and will protectpublic health in communities across the country. We look forward to a continued dialogue with you and your staffas we worktogetherto implementthe 2012 annual PM2.s standard. Should you have any questions, please do nothesitate to contact me, orhave your staffcontact Crystal Ostigaard ofmy staffat (303) 312-6602 or ostigaard.crystal@epa.gov.

Shaun L. Regional Administrator

cc: Larry Wolk, M.D., MSPH, Executive Director and ChiefMedical Officer MarthaRudolph, Director, CDPHE Will Allison, Director, APCD

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