The Honorable Mary Fallin 

Governor of Oklahoma 

2300 Lincoln Boulevard, Suite 212 

Oklahoma City, Oklahoma 73105 

Dear Governor Fallin: 

Thank you for your recommendations dated August 17, 2015, on air quality designations for the state of 

Oklahoma for the 20 10 revision to the primary National Ambient Air Quality Standard (NAAQS) for 

sulfur dioxide (S02). Reducing levels of S~ pollution is an important part of the U.S. Environmental 

Protection Agency's commitment to a clean, healthy environment. Exposure to S02 can cause a range of 

adverse health effects, including narrowing of the airways which can cause difficulty breathing and 

increased asthma symptoms. This letter is to notify you of the EPA's preliminary intentions regarding 

your recommended designations. 

On June 3, 2010, the EPA strengthened the health-based or "primary" standard for S02 by establishing a 

standard for 1-hour average S02 concentrations at a level of 7 5 parts per billion. Within one year after a 

new or revised standard is established, the Clean Air Act 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. Through an interactive process, the EPA considers the recommendations and then promulgates 

designations for all areas across the country. On July 25, 2013, the EPA designated 29 areas in 16 states 

as nonattainment, but did not at that time designate other areas. Pursuant to a March 2, 2015, courtordered schedule, I the EPA must complete the remaining so2 designations by three specific deadlines: 

July 2, 2016, December 31, 2017, and December 31,2020. 

This current round of designations, to be completed by July 2, 2016, addresses two groups of areas: ( 1) 

areas that have newly monitored violations of the 2010 S02 NAAQS based on the most recent three 

calendar years of certified monitored ambient air quality data, and (2) areas that contain any stationary 

source that had not been announced as of March 2, 2015, for retirement and that according to the EPA's 

Air Markets Database emitted in 2012 either (i) more than 16,000 tons of S02 or (ii) more than 2,600 

tons of S02 with an annual average emission rate of at least 0.45 pounds of S02/mmBTU. 

After carefully considering Oklahoma's recommendations and other available technical information, the 

EPA ·intends to designate as nonattainment or unclassifiable/attainment the following areas, including 

the following counties or portions of counties: 

1 Sierra Club v. McCarthy, No. 3-13-cv-3953 (SI) (N.D. Cal. Mar. 2, 2015). 

This paper is printed with vegetable-oil-based inks and is 100-percent postconsumer recycled material, 

chlorine-free-processed and recyclable 
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Intended Unclassifiable/ Attainment 

Area 

Noble County, Oklahoma 

Choctaw County, Oklahoma 

Intended Unclassifiable/ Attainment 

Area Counties 

Noble County 

Choctaw County 

The enclosed Technical Support Document provides a detailed analysis that supports our intended 

designation decisions. If your state has additional information that the EPA should consider prior to 

finalizing these designations, please submit it to us by Aprill9, 2016. We also will be publishing a 

notice in the Federal Register announcing a 30-day period for the public to provide input on the EPA's 

intended designation decisions. We will promulgate the designations for these areas by July 2, 2016. We 

will designate all other previously undesignated areas in the state on a schedule consistent with the 

prescribed timing of the court order, i.e., by December 31, 2017, or December 31, 2020. 

We look forward to a continued dialogue with you and your staff as we work together to complete the 

area designations and implement the 2010 primary S02 standard. For additional information regarding 

designations under the S02 standard, please visit our website at www.epa.gov/so2designations. Should 

you have any questions, please do not hesitate to call me, or have your staff contact Mr. Guy Donaldson 

of my staff at (214) 665-7242, or via email at Donaldson.guy@epa.gov. 

Ron Curry, 

Regional dmini~tor Enclosure 

cc: Mr. Michael Teague 

Oklahoma Secretary of Energy and Environment 

Mr. Scott Thompson 

Executive Director, Oklahoma Department of Environmental Quality