ir 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 

March 23, 2010 

Mr. Jared Blumenfeld 

Regional Administrator 

U.S. Environmental Protection Agency
 

Region 9
 

75 Hawthorne Street
 

San Francisco, California 94105
 

Dear Mr. Blumenfeld: 

The Air Resources Board (ARB) requests that the U.S. Environmental Protection 

Agency (U.S. EPA) grant the Southern Mountain Counties 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, Southern Mountain Counties were 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 the Southern Mountain Counties under subpart 2 as a 

"Moderate nonattainment area" with an attainment date of June 15, 2010 (74 CFR 

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 final action to classify the Southern Mountain 

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

U.S. EPA guidance specifies that the design vaiue 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, the date of June 15, 2010 is based on ozone levels 

from 2007-2009. Data recorded at the Southern Mountain Counties air quality 

monitoring sites indicates that air quality in the Southern Mountain Counties is 

improving to the point that the fourth highest daily average at all sites is well below the 

standard in 2009. However, the 2009 design value for the Southern Mountain Counties 

still exceeds the standard as illustrated by Table 1 in the enclosure. 

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 

March 23, 2010 

Page 2 

applicable SIP; 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, and for the second year, the area's fourth highest daily 8-hour 

value averaged over the original attainment year and the first extension year, is 0.084 

ppm or less. We believe that the Southern Mountain Counties, as a former Subpart 1 

area, has met both of these criteria and it is appropriate for U.S. EPA to grant the first 

one-year extension. The supporting documentation for our request is described below 

and contained in the enclosure. 

Table 1 demonstrates that the Southern Mountain Counties fourth highest 8-hour ozone 

average for 2009 is below the standard and qualifies the Southern Mountain Counties 

for a one-year extension of their 8-hour ozone attainment date. Table 2 demonstrates 

that the Southern Mountain Counties was on track to attain the 8-hour ozone standard 

by its original attainment date under Subpart 1 of June 15, 2009. However, in 2008, the 

Southern Mountain Counties recorded multiple air quality exceedances at a time when 

numerous wildfires were burning throughout Northern California, and consequently did 

not meet its attainment date. If the 2008 exceptional events requests submitted to 

U.S. EPA on March 12, 2009 are approved, the Southern Mountain Counties will have 

attained the 1997 8-hour ozone standard. 

We believe the Southern Mountain Counties have clearly met the criteria for a one-year 

extension of the attainment date and that emissions are continuing to decline. 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, Deputy Executive Officer, at 

(916) 322-2739, or have your staff contact Ms. Karen Magliano, Chief, Air Quality Data 

Branch at (916) 322-7137. 

Sincerely, 

I 

'~j /", "'" •
 L/L,.L?v ~/ k

/ \-d
 

James N. Goldsten~ ( c: 

Executive Officer 

Enclosure 

cc: Ms. Debbie Jordan, Director 

U.S. Environmental Protection Agency
 

Air Division - Region 9
 

75 Hawthorne Street
 

San Francisco, California 94105
 

Continued next page. 
Mr. Jared Blumenfeld 

March 23, 2010 

Page 3 

Charles Mosher 

Air Pollution Control Officer 

Mariposa County 

P.O. Box 2039 (5101 Jones St:) 

Mariposa, California 95338 

Vicki Helmar 

Air Pollution Control Officer 

Tuolumne County 

2 South Green Street 

Sonora, California 95370 

Lynn Terry 

Deputy Executive Officer 

Executive Office 

Karen Magliano, Chief 

.Air Quality Data Branch 
Enclosure 

Table 1
 

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

Design Value for Southern Mountain Counties
 

(parts per million) 

Monitoring Site Fourth-Highest 8-hour Ozone Concentration Design Value 

2006 2007 2008 2009 2009 

Yosemite Natl 

Park-Turtleback 0.084­ 0.087 0.094 0.079 0.086 

Jerseydale 0.08 0.083 0.089 0.077 0.083 

Sonora 0.079 0.084 0.098 0.077 0.086 

Table 2
 

Southern Mountain Counties 8-hour Ozone Design Values from 2001 to 2009
 

(parts per million) 

Design Value 2001 2002 2003 2004 2005 2006 2007 2008 2009 

Southern Mtn. 

Counties 0.092 0.091 0.091 0.09 0.088 0.086 0.085 0.087 0.086 

0.095 \ Design Values 

0.09 JJ 

0.085 ~.-------------...::::::::;..;....:::::~----

o.osL --,--- ..,----,---,­

2001 2002 2003 2004 2005 2006 2007 2008 2009 I