UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 8 

1595 WYNKOOP STREET 

DENVER, CO 80202-1129 

Phone 800-227-8917 

http://www.epa.gov/region08 

8P-AR 'JUN 14 2011. 

The Honorable Matthew H. Mead 

Governor of Wyoming 

State Capitol 

Cheyenne, Wyoming 82002 

Dear Governor Mead: 

Thank you for your recommendations on air quality designations for the revised National 

Ambient Air Quality Standards for lead throughout Wyoming. This letter is to notify you of the 

U.S. Environmental Protection Agency's (EPA's) preliminary decision to designate all of 

Wyoming as attainmentlunclassifiable, and to inform you of our approach for completing the 

designations for the revised lead standards. Reducing levels of lead pollution is an important part 

of the EPA's commitment to a clean, healthy environment. Lead exposure can cause a range of 

adverse health effects, most notably in children. Exposures to low levels of lead early in life have 

been linked to effects on IQ, learning, memory, and behavior. 

On October 15, 2008, the EPA substantially strengthened the health-based or "primary" National 

Ambient Air Quality Standard by lowerin~ it from 1.5 micrograms per cubic meter (llg/m3) - a 

level set in 1978 - to a level of 0.15 Ilg/m . This stronger standard provides increased protection 

against adverse health effects associated with exposure to lead in at-risk groups, including 

children. To provide increased protection against lead-related environmental and other welfare 

effects, the EPA revised the secondary National Ambient Air Quality Standard to be identical in 

all respects to the revised primary standard. The EPA also determined that the pre-existing 

ambient lead monitoring network was inadequate for determining whether many areas are 

meeting the revised lead standard and established new criteria for siting ambient lead monitors 

and new data collection requirements. Monitors meeting the new network siting requirements 

were to begin operation January 1,2010. 

Within two years of promulgating new or revised National Ambient Air Quality Standards, the 

Clean Air Act requires the EPA to complete the initial process of identifying or designating areas 

that meet or do not meet an air quality standard. If the Administrator has insufficient information 

to make these designations, the EPA has the authority to extend the designation process by up to 

one year. In light of the new monitoring network, the EPA is completing the lead designations in 

two rounds. In the first round, published on November 16,2010, the EPA designated as 

"nonattainment" 16 areas as violating the 2008 Lead National Ambient Air Quality Standards 

based on data from the pre-201O monitoring network. For all other areas, the EPA extended the 
deadline for designations by up to one year so that data from the newly deployed monitors can be 

considered in making appropriate designation decisions. States were given an opportunity to 

update their recommendation letters for those remaining areas for our consideration in the second 

round of designations by December 15, 2010. The EPA intends to complete the second round of 

lead designations by no later than October 14, 2011. 

Consistent with the Clean Air Act, and after carefully considering Wyoming's October 8,2009 

recommendation letter, and all the associated technical information for the 2008 Lead National 

Ambient Air Quality Standards, including the most recent air quality data from 2008-2010, the 

EPA is proposing to adopt Wyoming's recommended designations. 

If your state has additional information that the EPA should consider with respect to our 

proposed modification to your designation recommendation, please submit it to us by 

August 15,2011. The EPA's preliminary designation decisions and supporting documentation 

will be made available to the general public for review. We will be accepting comments through 

August 15,2011. We will review any information we receive from the state of Wyoming and the 

general public by this date, and we plan to promulgate the second round of final designations by 

October 14,2011. 

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

implement the 2008 Lead National Ambient Air Quality Standards. Should you have any 

questions, please do not hesitate to call me, or have your staff contact Carl Daly ofmy staff at 

(303) 312-6416. 

Sincerely, 

cc:	 John V. Corra, Environmental Director 

Wyoming Department of Environmental Quality 

Gina McCarthy, Assistant Administrator for Air and Radiation 

Steven D. Page, Director, Office of Air Quality Planning and Standards