The American Lung Association just released its 2007 State of the Air report, which tracks levels of particle pollution and ozone in the air nationwide. Air pollution doesn't just contribute to global warming; it also can have a serious effect on a person's health, in both the short- and long-term. According to the report, 46 percent of Americans live in counties with unhealthy levels of ozone or particle pollution.

Ten Most Polluted Cities (Short-Term Particle Pollution)
1. Los Angeles-Long Beach-Riverside, CA
2. Pittsburgh-New Castle, PA
3. Fresno-Madera, CA
4. Bakersfield, CA
5. Logan, UT-ID
6. Birmingham-Hoover-Cullman, AL
7. Salt Lake City-Ogden-Clearfield, UT
8. Detroit-Warren-Flint, MI
9. Eugene-Springfield, OR
10. Cleveland-Akron-Elyria, OH

Look up the status of your city, county, or state, or find more information about the health effects of air pollution in the full report at the links below.

State of the Air: 2007 [customizable]
Cleanest and Most-Polluted Cities and Counties
Health Effects of Ozone and Particle Pollution

NASA photo of pollution in the atmosphere over Northern New York.