1. Department of Economics, California State University, Fullerton, CA 92634.
2. Environmental Science and Engineering Program, Department of Environmental Health Sciences, School of Public Health, University of California, Los Angeles, CA 90024.
3. Department of Community and Environmental Medicine, Air Pollution Health Effects Laboratory, University of California, Irvine, CA 92715.
4. Sonoma Technology, Incorporated, Santa Rosa, CA 95403.
5. Integrated Environmental Services, Irvine, CA 92715.