EOSrqr,s UNITED STATES ENVIRONMENTAL PROTECTION AGENCY w Q WASHINGTON, D.C. 20460



## JAN 2 6 1011

THEADMINISTRATOR The Honorable Janice K . Brewer Governor ofArizona 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 ofstate 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), EPAis 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 EPAas we take this step to informcitizens about their air quality and begin the process of protecting public health by reducing levels offine 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 1/301h 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 roomvisits for respiratory and cardiovascular disease. On October 17, 2006, EPAstrengthened the primary and secondary 24-hour PM2 .5 NAAQS from65 pg/m3to 35 Fig/m3. EPAprovided 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 EPAon 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 ofair 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, EPAnotified 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, EPAdeferred the area designation of Pinal County, Maricopa County (the other county comprising the Phoenix-Mesa-Scottsdale coreInternet Address (URL) e http //www .epa gov Recycled/Recyclable e Printed with Vegetable Oil Based Inks on 1001 Postconsumer, Process Chlorine Free Recycled Paperbased 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, EPAsent 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 ofPinal 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 whichwas smaller than the boundary EPAoriginally proposed. EPAreviewed your July 19, 2010letter 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 EPAto complete the process ofdesignating areas as "nonattainment," "attainment," or "unclassifiable" within two years ofestablishing a new or revised NAAQS

. For the designated Pinal County nonattainment area, Arizona must develop a State Implementation Plan (SIP) that provides for attainment ofthe NAAQS as expeditiously as practicable, in accordance with the requirements ofthe CAAand applicable EPAregulations. Pursuant to CAAsection 172(b), EPA is announcing that this plan must be submitted no later than three years fromthe effective date ofthis designation, or by March 2014. The partial Pinal County nonattainment area must attain the 200624-hour PM2 .5 NAAQS as expeditiously as practicable, but no later than five years fromthe effective date of nonattainment designation. Staffin your EPA regional office is available to answer questions that you or your staffmay have. You can also find additional technical information regarding the designations process by visiting http://www

.epa.gov/pmdesi nag- tions. Thankyou for your continued work to improve air quality. We look forward to working with staffof the Arizona Department of Environmental Quality onthese matters. Ifyou have further questions, please contact me or your staff maycall Sarah Hospodor-Pallone, Deputy Associate Administrator for Intergovernmental Relations, at 202-564-7178. Sincerely,

Lisa P. Jackson