Ref: 8P-AR UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595 Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08



### AUG 1

### 9 2014

The Honorable Darrell O'Neal Sr., Chairman Northern Arapaho Tribe P.O. Box 396 Ft. Washakie, Wyoming 82514

Dear Chairman O'Neal:

This letter is to notify you ofthe U.S. Environmental ProtectionAgency's preliminary decision to designate the Northern Arapaho Tribe's area ofIndian country as unclassifiable/attainment for the 2012 revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard (NAAQS) and to inform you ofour approach for completing the designations. Although your involvement is not required,

we would like to invite you to participate in the designations process and to offer you consultation.

On December 14, 2012, the EPA promulgated a revised primary annual PM2.s NAAQS (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 (J.tg/m3) to 12.0 J.tg/m3; retained the existing 24-hour PM2.s standard at 35 J.tg/m3; retained the existing 24-hourPM10(coarse particle) standard at 150 J.tg/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 our body 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-risk populations 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 implementingthe standards using a commonsense approach that improves air quality and minimizesthe burden on state, local, and tribal governments. As part of this routine process, the EPA is working with the states and tribes to identify areas inthe country that
meet the 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 AirAct (CAA) requires the Governor ofeach state to submitto the EPA a list ofall areas inthe state, withrecommendations for whether each

area meets the standard. Althoughtribes are not required to submitrecommendations, the EPA encourages tribes to participate inthe designations process, and provides them with an opportunity to submitrecommendations ifthey choose to do so. Participatingtribes are requested to follow the same schedule as states, ifpossible. States andtribes were asked to submittheir designation recommendations, including appropriate areaboundaries, by December 13, 2013.

In a letter dated May 22, 2014, the EPA encouragedyou to participate in the designations process, request consultation, and submitrecommendations ifyou chose to do so. We did not receive a recommendation letter or consultation request from you. However, because the EPA is required to designate all areas ofthe country, we intend to promulgate an appropriate designation for your area of Indian country. This is notthe final step in the designation process, and you still have time to provide air quality information to the EPA and request consultation. More informationregarding this designation is included below.

As required by the CAA, the EPApromulgates designations for all areas across the country. The EPA designates an area as "nonattainment" if

### itis violating the NAAQS or ifit is contributing to 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 contributing to nearby violations. Additionally, the EPA intends to designate as "unclassifiable"those areas where the EPAeither cannot determine based on available information whether the area is meeting the NAAQS, orhas not determined whetherthe area contributesto a nearby violation. At this time, the EPAis proceeding with intended initial area designations using qualityassured, certified air quality monitoring datafrom 2011 to 2013.

After considering relevanttechnical information, including 2011-2013 air quality data, the EPA intends
to designate your areaofIndian country as unclassifiable/attainment along withthe surrounding state

area. These data do not indicate any violation ofthe 2012 annual PM2.s NAAQS inNorthern Arapaho Tribe's area ofIndian country or contributionto any nearby area. Consequentlythe EPA intends to designate the Northern Arapaho Tribe's entire are oflndiancountry as unclassifiable/attainment. Ifyou have additional information that the EPA should consider, we ask that you submit it to us by October 29, 2014.

Please notify us by September 29, 2014 ifyou are interested inconsulting withus regarding the designations process. Whenrequested, consultation will be conducted in accordance with the EPA Policy on Consultation andCoordination with Indian Tribes (www.epa.gov/tribal/consultationlconsultpolicy.htm).

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-day public commentperiod shortly in the Federal Register. After considering additional information we receive, the EPAplans 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- includingpollution reduction rules for powerplants, vehicles, and fuels- will assure steady progress to reduce PM2.s-forming pollution and will protectpublic health in communities across the country. We look forward to working together with you and your staffto implementthe 2012 annual PM2.s standard. Ifyourtribe is interested in consultation orparticipating in further discussions or meetings with the EPA officials about the designations process, please do not hesitate to contact me, orhave your staffcontact Crystal Ostigaard ofmy staffat (303) 312-6602 orostigaard.crystal@epa.gov.

cc: Ryan Ortiz, Environmental Director Jolene Catron, Air Coordinator Regional Administrator

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