1. Los Angeles Almanac: http://www.losangelesalmanac.com/topics/Population/index.htm#Historical Demographics. (Accessed July 2001).
2. Houston, Texas supplanted Los Angeles as the smog capital of US in October 1999. Source: US News & World Report: Houston, you have a problem and it’s smog (10/25/99).
3. Website of California Air resources Board: http://www.arb.ca.gov/homepage.htm. (Accessed July 2001).
4. Information obtained from South Coast Air Quality Management District website: http://www.aqmd.gov/. (Accessed July 2001).
5. Website of California Air resources Board: http://www.arb.ca.gov/homepage.htm. (Accessed July 2001).