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 of the U.S. Environmental Protection Agency's preliminary decision to 

designate the Northern Arapaho Tribe's area of Indian country as unclassifiable/attainment for the 2012 

revised primary annual fine particle (PM2.s) National Ambient Air Quality Standard (NAAQS) and to 

inform you of our 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 per cubic 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-hour PM10(coarse particle) standard at 150 J.tg/m3; and 

retained the current suite of secondary PM standards. The 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 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, 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 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 (CAA) requires the Governor of 
each state to submit to the EPA a list of all areas in the state, with recommendations for whether each 

area meets the standard. Although tribes are not required to submit recommendations, the EPA 

encourages tribes to participate in the designations process, and provides them with an opportunity to 

submit recommendations if they choose to do so. Participating tribes are requested to follow the same 

schedule as states, if possible. States and tribes were asked to submit their designation 

recommendations, including appropriate area boundaries, by December 13, 2013. 

In a letter dated May 22, 2014, the EPA encouraged you to participate in the designations process, 

request consultation, and submit recommendations if you 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 not the final step in the designation process, and you still have time to provide air 

quality information to the EPA and request consultation. More information regarding this designation is 

included below. 

As required by the CAA, the EPA promulgates designations for all areas across the country. The EPA 

designates an area as "nonattainment" if it is violating the NAAQS or if it is contributing to a violation 

of the 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 which the EPA has 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 EPA either cannot determine based on available information 

whether the area is meeting the NAAQS, or has not determined whether the area contributes to a nearby 

violation. At this time, the EPA is proceeding with intended initial area designations using qualityassured, certified air quality monitoring data from 2011 to 2013. 

After considering relevant technical information, including 2011-2013 air quality data, the EPA intends 

to designate your area of Indian country as unclassifiable/attainment along with the surrounding state 

area. These data do not indicate any violation of the 2012 annual PM2.s NAAQS in Northern Arapaho 

Tribe's area of Indian country or contribution to any nearby area. Consequently the EPA intends to 

designate the Northern Arapaho Tribe's entire are oflndian country as unclassifiable/attainment. If you 

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 if you are interested in consulting with us regarding the 

designations process. When requested, consultation will be conducted in accordance with the EPA 

Policy on Consultation and Coordination 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 comment period shortly 

in the Federal Register. After considering additional information we receive, the EPA plans to 

promulgate final annual PM2.s designations in December of2014. 
The 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 assure steady progress to reduce PM2.s-forming 

pollution and will protect public health in communities across the country. We look forward to working 

together with you and your staff to implement the 2012 annual PM2.s standard. If your tribe is interested 

in consultation or participating in further discussions or meetings with the EPA officials about the 

designations process, please do not hesitate to contact me, or have your staff contact Crystal Ostigaard 

of my staff at (303) 312-6602 or ostigaard.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 of Air Quality Planning and Standards