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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

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Q WASHINGTON, D .C . 20460 

JAN 2 6 1011 

THE ADMINISTRATOR 

The Honorable Janice K. Brewer 

Governor of Arizona 

1700 West Washington Street 

Phoenix, Arizona 85007 

Dear Governor Brewer: 

Based on 2006-2008 air quality data, the U.S . Environmental Protection Agency (EPA) 

has determined that a portion of state lands in Pinal County, Arizona does not meet the 2006 24-

hour fine particle (PM2.5) national ambient air quality standards (NAAQS). As directed by the 

Clean Air Act (CAA), EPA is designating this area as "nonattainment ." Eight counties 

surrounding Pinal County are being designated as "unclassifiable/attainment." I appreciate the 

information that Arizona has shared with EPA as we take this step to inform citizens about their 

air quality and begin the process of protecting public health by reducing levels of fine particles in 

the air. 

Fine particle pollution represents one of the most significant barriers to clean air facing 

our nation today. Health studies link these tiny particles - about 1/3 01h the diameter of a human 

hair - with serious human health problems including premature death in people with heart and 

lung disease; nonfatal heart attacks; and increased hospital admissions and doctor and emergency 

room visits for respiratory and cardiovascular disease. 

On October 17, 2006, EPA strengthened the primary and secondary 24-hour PM2.5 

NAAQS from 65 pg/m3 to 35 Fig/m3 . EPA provided guidance to states and tribes for 

recommending nonattainment area boundaries for the 24-hour PM2.5 standard in June of 2007 . 

Arizona provided its initial designation recommendations to EPA on December 19, 2007. This 

recommendation was based on 2004-2006 ambient monitoring data. For that period, Pinal 

County had no monitoring site with complete data indicating a violation of the standard . While 

EPA initially agreed with these recommendations, the delay in finalizing the 24-hour PM2.5 

NAAQS designations resulted in the availability of air quality monitoring data through the end of 

2008. Through our review of these data, EPA determined that the "Cowtown" monitor in Pinal 

County was violating the 24-hour PM2.5 NAAQS based on 2006-2008 data. 

In October of 2009, EPA notified your office of the violating monitor. Due to this new 

violation, and due to the need for additional time to collect data and evaluate the area to 

determine an appropriate nonattainment area boundary, EPA deferred the area designation of 

Pinal County, Maricopa County (the other county comprising the Phoenix-Mesa-Scottsdale coreInternet Address (URL) e http //www.epa gov 

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based statistical area (CBSA)), and the seven nearby counties (Cochise, Gila, Graham, La Paz, 

Pima, Yavapai, and Yuma Counties) surrounding the Phoenix-Mesa- Scottsdale CBSA, for the 

24-hour PM2.5 standards. 

In April and May of 2010, EPA sent letters to Arizona notifying the state of EPA's 

intentions with respect to potential modification of the initial designation recommendations for 

Pinal County. In a letter dated July 19, 2010, you responded to EPA's notification of the need 

for a modification to the state's initial designation to designate a portion of Pinal County 

"nonattainment" for the 24-hour PM2.5 NAAQS. In this letter, you disagreed with EPA's 

modification, but also provided a revised recommendation with a suggested boundary for the 

nonattainment area in Pinal County which was smaller than the boundary EPA originally 

proposed. EPA reviewed your July 19, 2010 letter and associated documentation and is now 

making a revised boundary determination that includes the sources of PM2.5 and PM2.5 precursor 

emissions that contribute to air quality violations at the "Cowtown" monitor. The final partial 

Pinal County, Arizona nonattainment area remains larger than the area you recommended in your 

July 19, 2010 letter but excludes the Table Top Wilderness Area. 

The Clean Air Act requires EPA to complete the process of designating areas as 

"nonattainment," "attainment," or "unclassifiable" within two years of establishing a new or 

revised NAAQS. For the designated Pinal County nonattainment area, Arizona must develop a 

State Implementation Plan (SIP) that provides for attainment of the NAAQS as expeditiously as 

practicable, in accordance with the requirements of the CAA and applicable EPA regulations. 

Pursuant to CAA section 172(b), EPA is announcing that this plan must be submitted no later 

than three years from the effective date of this designation, or by March 2014. The partial Pinal 

County nonattainment area must attain the 2006 24-hour PM2.5 NAAQS as expeditiously as 

practicable, but no later than five years from the effective date of nonattainment designation. 

Staff in your EPA regional office is available to answer questions that you or your staff may 

have . You can also find additional technical information regarding the designations process by 

visiting http://www.epa.gov/pmdesi nag- tions. 

Thank you for your continued work to improve air quality. We look forward to working 

with staff of the Arizona Department of Environmental Quality on these matters. If you have 

further questions, please contact me or your staff may call Sarah Hospodor-Pallone, Deputy 

Associate Administrator for Intergovernmental Relations, at 202-564-7178. 

Sincerely, 

Lisa P. Jackson