August 12, 1999

Ms. Felicia Marcus
Regional Administrator
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105

Dear Ms. Marcus:

In response to the U.S. Environmental Protection Agency’s (U.S. EPA’s) June 25, 1999 guidance regarding area designations for the new eight-hour ozone National Ambient Air Quality Standard, I am transmitting the attached list of California air
quality monitors that violate the standard. The list is based on the fourth highest eight-hour ozone value recorded from 1996 through 1998.

All related ozone monitoring data have been automatically submitted to U.S. EPA’s Aerometric Information Retrieval System (AIRS). The data submitted to AIRS include the most recent ozone concentration data from the National Air Monitoring Stations and the State and Local Air Monitoring Stations networks for the 1996-1998 period. We have also submitted those data from the Special Purpose Monitoring network
that we believe are representative of population exposure.

We have worked closely with local air pollution control districts and your office
to develop recommendations on area designations and boundaries for the
eight-hour ozone standard. In May 1999, we held a public workshop on proposed boundary recommendations. We expect to present an updated version of our area designation and boundary recommendations, based on 1997-1999 data, to our
Board in early 2000. We will submit these recommendations to U.S. EPA in early 2000, before the Agency finalizes the area designations in July 2000.

As we have discussed with your staff, we are not including data from either of the
two special purpose monitors on the Sutter and Tuscan Buttes in the Sacramento Valley. These elevated sites were installed for the sole purpose of studying ozone
and ozone precursor transport aloft and should not be used for area designations.
For the Sutter Buttes site, monitors in nearby communities at lower elevations show attainment. For the Tuscan Buttes, the monitoring site is not representative of population exposure even in foothill communities at similar elevation. U.S. EPA staff has cited a court decision on the use of special purpose monitoring data, and the resulting 1997 policy memorandum, as allowing no flexibility on the use of these data for area designations. We disagree. As presented in the 1997 memorandum, the scope of U.S. EPA’s policy is much broader than the court decision itself. Our legal staff has reviewed the court decision and believes it does not limit U.S. EPA’s discretion to exclude special purpose data in this situation. U.S. EPA can and should exclude the data from the Sutter and Tuscan Buttes sites in making designations for the eight-hour ozone standard because pollutant levels at these isolated, elevated sites are not representative of ozone exposure to the population.

If you have any questions or would like to discuss the attached information, please call me at (916) 445-4383 or Ms. Lynn Terry, Deputy Executive Officer, at (916) 322-2739.




Michael P. Kenny
Executive Officer


cc:   (with attachment)
Alan C. Lloyd, Ph.D., Chairman
All Air Pollution Control Officers
Stew Wilson, California Air Pollution Control Officers Association

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Area Designations for Federal 8-hour Ozone Standard

California Environmental Protection Agency

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