OST4) UNITED STATES ENVIRONMENTAL PROTECTION AGENCY I
REGION.
IX PRO

75 Hawthorne Street San Francisco, CA 94105-3901

OFFICEOFThE FEB
062013 REGIONALADMINISTRATOR The Honorable Brian Sandoval State Capitol Building 101 North Carson Street Carson City, Nevada 89701 Dear Governor Sandoval: Thank youfor yourstaff’s recommendations dated May 3, 2011 onair quality designations for the state of Nevada for the 2010 revision
to the primary National Ambient Air Quality Standard for sulfur dioxide (SO 2 ). Reducing levels of SO 2 pollution

is an important part of the U. S. Environmental Protection Agency’s (EPA) commitment

to a clean, healthy environment. Exposure
to SO2 cancause

a rangeof adverse health effects, including nanowing of the airways which cancause difficulty breathing and increased asthma symptoms. This letter is to notify youof the EPA’s preliminary intentions regarding yourrecommended designations. On June 3, 2010, the EPA strengthened the health-based

or “primary” standard for SO 2 by establishing

a standard for 1-hour averageSO 2 concentrations

at alevel of 75 parts perbillion. The Clean Air Act requires the EPA to complete the initial designations processwithin two yearsof promulgating

anewor revised standard.
If the Administrator has insufficient information

to make these designations, the EPA has the authority
to extend the designation process by upto one year.On July 27, 2012, the EPA announced that it had insufficient information

to complete the designations for the 1-hour SO 2 standard within two yearsand extended the designations deadline
to June 3, 2013. At this time the EPA is proceeding with designating

asnonattainment most areasin locations where existing monitoring data from 2009-20
11 indicate violations of the 1-hour SO 2 standard. The EPA intends to address the designations for all other areasin separate future actions. With input from
a diverse groupof stakeholders, EPA has developed

a comprehensive implementation strategy for these future actions that focuses resourceson identifying and addressing unhealthy levels of SO 2 .The strategy
is available at: www.epa.gov/airguality/sulfurdioxide/implement.html.

The EPA will continue to work closely with youand ourother partners
at the state, tribal and local levels to ensurehealthprotective, commonsense implementation

of the 1-hour SO 2 standard. The EPA’s review of the most recent monitored air quality data from 2009-2011 shows noviolations of the 2010 SO 2 standard
in anyareasin Nevada. Consequently,
the EPA is not yet prepared
to propose designation action in Nevada and is therefore currently deferring action to designate areasin Nevada. The EPA expects to be able to proceed with designation action in Nevada onceadditional data are gathered pursuant
to our comprehensive implementation strategy. In a separate future action oractions PrintedonRecycled Paperthe EPA will notify you of our intended designations for these areas, and seek public comment on these actions, no later than 120 days prior to promulgating any final designations. We look forward to a continued dialogue with you and your staff as we work together
to implement the 2010 primary SO 2 standard. For additional information regarding initial designations
of the SO 2 standard, please visit our website at: www.epa.ov/so2designations. Should you have any questions, please do not hesitate to call me, or have your staff contact Deborah Jordan, Director, Air Division
at 415-947-8715,

or

j ordan.deborah(epa.gov. Sincerely, ,, 4 rJared Blumenfeld cc: Colleen Cripps, Administrator, Nevada Division of Environmental Protection Mike Elges, Deputy Administrator, Nevada Division of Environmental Protection Rob Bamford, Chief, Air Quality Planning Bureau, Nevada Division of Environmental Protection Lewis Wallenmeyer, Director, Clark County Department
of Air Quality and Environmental Management Kevin Dick, Director, Air Quality Management Division, Washoe County Board of Health Gina McCarthy, Assistant Administrator
for Air and Radiation Stephen D. Page, Director, Office of Air Quality Planning and Standards