Air Resources Board
 

Mary D. Nichols, Chairman 

1001 I Street· P.O. Box 2815 

Linda S. Adams Sacramento, California 95812' www.arb.ca.gov Arnold Schwarzenegger 

Secretary for Governor 

Environmental Protection 

May 24,2010 

Mr. Jared Blumenfeld
 

Regional Administrator
 

United States Environmental Protection Agency
 

Region 9
 

75 Hawthorne Street
 

San Francisco, California 94105
 

Dear Mr. Blumenfeld: 

The Air Resources Board (ARB) requests that the United States Environmental 

Protection Agency (U.S. EPA) grant the Western Nevada County 8-hour ozone 

nonattainment area a one-year extension of the 1997 8-hour ozone national ambient air 

quality standard (standard) attainment date. 

On April 15, 2004, Western Nevada County was designated nonattainment for the
 

federal 8-hour ozone standard and classified as a basic area. On January 16, 2009,
 

U.S. EPA proposed to reclassify Western Nevada County under subpart 2 as a 

moderate nonattainment area with an attainment date of June 15, 2010 (74 FR 2936). 

U.S. EPA has yet to finalize this ruling and has therefore not officially set an attainment 

date for this area. However, ARB believes that U.S. EPA could propose to grant a 

one-year extension now, pending taking final action to classify Western Nevada County 

as a moderate area with an attainment date of June 15, 2010. 

U.S. EPA guidance specifies that the design value for this standard is the three-year 

average of the fourth-highest daily maximum 8-hour average ozone concentrations 

measured at each monitoring station. Since three full years of air quality data are 

needed to demonstrate attainment, attainment by June 15, 2010, is based on ozone 

levels from 2007-2009. Data recorded at Western Nevada County air quality monitoring 

sites indicates that air quality in Western Nevada County still exceeds the standard but 

qualifies for the extension as illustrated by Table 1 in the enclosure. This request is 

based upon the area's 2009 fourth highest daily 8-hour ozone concentration. 

The 8-hour ozone implementation rule gives U.S. EPA the discretion to grant up to two 

one-year extensions of the attainment date upon application by a state if: 1) the state 

has complied with all requirements and commitments pertaining to the area in the 

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California Environmental Protection Agency 

Printed on Recycled Paper 
Mr. Jared Blumenfeld 

May 24,2010 

Page 2 

applicable State Implementation Plan; and 2) air quality data show that for the first 

one-year extension, the area's fourth highest daily 8-hour average in the attainment 

year is 0.084 parts per million (ppm) or less. To qualify for a second one-year 

extension, the area's fourth highest daily 8-hour value averaged over the original 

attainment year and the first extension year must be 0.084 ppm or less. 

On February 8, 2008, ARB submitted a Reasonably Available Control Technology State 

Implementation Plan (RACT SIP) for Western Nevada County for Control Technology 

Guidelines (CTGs) up through 2005. On August 18, 2008, ARB submitted a RACT SIP 

for Western Nevada County for CTGs for 2006 and 2007. We believe with these RACT 

submissions that Western Nevada County has met, or surpassed, the first requirement 

to qualify for a one-year extension. Table 1, in the enclosure, demonstrates that 

Western Nevada County's fourth highest 8-hour ozone average for 2009 is below the 

standard, satisfying the second requirement to qualify for a one-year extension. 

We believe that Western Nevada County has met both of the criteria for the first 

one-year extension of their 8-hour ozone attainment date and it is appropriate for 

U.S. EPA to grant such. We look forward to U.S. EPA approval of this request for an
 

extension of the attainment date. If you have any questions, please call Ms. Lynn Terry,
 

Deput Executive Officer, at (916) 322-2739, or have your staff contact Ms. Karen
 

Ma no, Chief, Air Quality Data Branch at (916) 322-7137.
 / 

Enclosure 

cc: See next page. 
Mr. Jared Blumenfeld 

May 24,2010 

Page 3 

cc:	 Ms. Deborah Jordan, Director 

United States Environmental Protection Agency 

Air Division-Region 9 

75 Hawthorne Street 

San Francisco, California 94105 

Ms. Gretchen Bennitt 

Air Pollution Control Officer 

Northern Sierra Air Quality Management District 

P.O. Box 2509 

200 Litton Drive, Suite 320 

Grass Valley, California 95945-2509 

Ms. Lynn Terry
 

Deputy Executive Officer
 

Ms. Karen Magliano, Chief 

Air Quality Data Branch 

Planning and Technical Support Division 
Table 1
 

Fourth Highest 8-hour Ozone Daily Maximums for 2006 to 2009
 

and 2009 Design Value for Western Nevada County
 

(parts per million) 

Fourth-Highest 8-hour Ozone 

Monitoring Site Concentration Design Value 

2006 2007 2008 2009 2009 

Grass Valley-Litton 

Building 0.096 0.088 0.091 0.083 0.087 

White Cloud 

Mountain 0.089 0.082 0.091 0.077 0.083