Terry Tamminen 

Agency Secretary

 

The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. 

For a list of simple ways you can reduce demand and cut your energy costs, see our Website: http://www.arb.ca.gov. 

California Environmental Protection Agency

Printed on Recycled Paper

Air Resources Board Alan C. Lloyd, Ph.D. 

Chairman 

1001 I Street • P.O. Box 2815 

Sacramento, California 95812 • www.arb.ca.gov 

Arnold Schwarzenegger

 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 for 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 Resources 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 measured from 2000 through 2002 by 110 monitors located at 81 

stations across California. Pending complete data for 2003, ARB’s preliminary 

recommendation is that the U.S. Environmental 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 standards. Finally, 22 areas should be deemed 

unclassifiable, where air quality data are insufficient 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 indicates 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 monitoring 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 boundary for each region. These coincide with 

the existing federal one-hour ozone nonattainment areas and ARB’s recommended 

eight-hour ozone nonattainment areas as well. 

ARB staff believes that violation of the annual PM2.5 standard in Calexico in 2000-2002 

results from emissions in the densely populated international Calexico/Mexicali border 

region. The level of urban activity and PM2.5 pollution in the Calexico/Mexicali area are 

distinct and not representative of the rest of Imperial 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 limited to the City of Calexico. 

Enclosures. We include the following materials in this package: 

• Recommended nonattainment/attainment/unclassifiable areas (Enclosure 1). 

• Information supporting recommendations for nonattainment areas (Enclosure 2). 

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

• 2000-2002 data for all of California’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/planning/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 Branch, 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