UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION IX 

The Honorable JaniceK. Brewer 

1700 West Washington Street 

Phoenix, Arizona 85007 

Dear Governor Brewer: 

75 Hawthorne Street 

San Francisco, CA 94105-3901 

AUG 1 9 7014 

OFFICE OF THE 

REGIONAL ADMINISTRATOR 

Thank you for your recommendation, dated December 10, 2013, of air quality designations for the 2012 

annual fine pariicle National Ambient Air Quality Standard (2012 armual PM2.s NAAQS) throughout 

Arizona. This letter is to notify you of the U.S. Environmental Protection Agency's (EPA) preliminary 

response to Arizona's recommendation and to inform you of our approach for completing the initial area 

designations for the 2012 annual PM2.s NAAQS. 

The EPA agrees with your December 10,2013 recommendation. We have considered the annual PM2.s 

designation recommendation submitted by Arizona and have reviewed the relevant technical 

information, including 2011-2013 air quality data. These data do not indicate any violation ofthe 2012 

ammal PM2.s NAAQS in Arizona or contribution to any nearby area. Accordingly, the EPA intends to 

designate the entire state of Arizona as unclassifiable/attainment. 

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 the additional information we receive, the EPA plans to 

promulgate final designations for the 2012 annual PM2.s NAAQS in December of2014. 

As background, 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 ammal PM2.s standard, 

strengthening it from 15.0 micrograms per cubic meter ()lg/m3

) to 12.0 )lg/m3; retained the existing 24-

hour PM2.s standard at 35 )lglm3

; retained the existing 24-hour PM10 (coarse particle) standard at 150 

)lglm3

; 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 armual 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 an·ay of PM2 s-related 

adverse health effects, including premature mortality, increased hospital admissions and emergency 

department visits, and development and exacerbation of chronic respiratory disease. 

The EPA designates an area as "nonattainment" if it is violating the 2012 annual PM2.s 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, and that the EPA has reason to believe are likely 

attaimnent and are not contributing to nearby violations. Additionally, the EPA intends to designate as 

Printed on Recycled Paper 
"unclassifiable" those areas where the EPA cannot determine based on available information whether 

the area is meeting the NAAQS or where EPA has not determined that 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. · 

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 ensure steady progress to reduce PM2.s-forming 

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

continued dialogue with you and your staff as we work together to implement the 2012 annual PM2.s 

NAAQS. Should you have any questions, please contact me, or have your staff contact Deborah Jordan 

of my staff at 415-947-8715, or jordan.deborah@epa.gov. 

Sincerely, 

cc: Hemy R. Darwin, Director, Arizona Department of Environmental Quality 

(via email) Eric Massey, Director, Air Quality Division, Arizona Department of 

Environmental Quality