Terry Tamminen Agency Secretary

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. California Environmental Protection Agency

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# Air Resources Board

Alan C. Lloyd, Ph.D.
Chairman

1001 I Street • P.O. Box 2815 Sacramento, California 95812 • www.arb.ca.gov Arnold Schwarzenegge r Governor

February 11, 2004

Mr. Wayne Nastri Regional Administrator Region 9
U.S. Environmental Protection Agency
75 Hawthorne Street San Francisco, California 94105-3901

Dear Mr. Nastri:

We are transmitting our recommendations fo r area designations under the federal air quality standards for particulate matter 2.5 microns or less in diameter (PM2.5). On behalf of the State of California, the Air Res ources Board (ARB) is responding to your June 3, 2003 letter to the Governor requesting these recommendations by February 15, 2004.

Four PM2.5 Nonattainment Areas. We base our initial recommendations on ambient
PM2.5 concentrations measur ed from 2000 through 2002 by 110 monitors located at 81 stations across California. Pending comp lete data for 2003, ARB’s preliminary
recommendation is that the U.S. Envir onmental Protection Agency (U.S. EPA) designate four areas as nonattainment for the PM2.5 standards:

• South Coast Air Basin,

• San Joaquin Valley Air Basin,

• San Diego County, and

• City of Calexico (on the California-Mexico border in Imperial County).

Eight areas should be designated attainment, where air quality data are sufficient to determine that they meet the federal st andards. Finally, 22 areas should be deemed unclassifiable, where air quality data are in sufficient to make a determination yet.

Updated Monitoring Data. We understand that U.S. EPA intends to promulgate PM2.5 area designations by December 2004, based on monitoring data from 2001 through 2003. Preliminary 2003 information indi cates that Calexico and several of the currently unclassifiable areas may now attain the PM2.5 standards. Before your final action, ARB will transmit PM2.5 monitori ng data for 2003 and any appropriate changes
to our initial recommendations for area designations.Mr. Wayne Nastri February 11, 2004 Page 2

Nonattainment Area Boundaries . The geographic scope of the federal PM2.5 nonattainment areas for the South Coast, San Joaquin Valley, and San Diego County
should be consistent with the air basin bounda ry for each region. These coincide with the existing federal one-hour ozone nonatta inment areas and ARB’s recommended eight-hour ozone nonattain ment areas as well.

ARB staff believes that violation of the annual PM2.5 standard in Ca lexico in 2000-2002 results from emissions in the densely popula ted international Calexico/Mexicali border region. The level of urban activity and PM2.5 pollution in the Calexi co/Mexicali area are distinct and not representative of the rest of Imper ial County. As a result, if Calexico
violates the federal PM2.5 standard after consideration of 2003 data, we recommend
that the U.S. nonattainment area be lim ited to the City of Calexico.

Enclosures. We include the following materials in this package:

• Recommended nonattainment/attainment/unc lassifiable areas (Enclosure 1).

• Information supporting re commendations for nonattainm ent areas (Enclosure 2).

• Legal descriptions for nonattainment area boundaries (Enclosure 3).

• 2000-2002 data for all of Ca lifornia’s PM2.5 monitoring sites (Enclosure 4).

To facilitate public access, we have posted this transmittal and related materials on our
website at: http://www.arb.ca.gov/p lanning/sip/sip.htm

.

If you have any questions, please call Ms. Lynn Terry, Deputy Executive Officer, at (916) 322-2739, or have your staff contact Ms. Cynthia Marvin, Chief, Air Quality and Transportation Planning Br anch, at (916) 322-7236.

Sincerely,

/s/

Catherine Witherspoon
Executive Officer

Enclosures

cc: See next page.Mr. Wayne Nastri February 11, 2004 Page 3

cc: (with Enclosure 1)

Air Pollution Control Officers

Directors of Metropolitan Planning Organizations

Ms. Deborah Jordan, Director Air Division, Region 9
U.S. Environmental Protection Agency
75 Hawthorne Street San Francisco, California 94105

Mr. Brian Smith Deputy Director Planning and Modal Programs California Department of Transportation
1120 N Street Sacramento, California 95812

Ms. Lynn Terry
Air Resources Board

Ms. Cynthia Marvin
Air Resources Board