Top 10 most polluted cities
Most ozone-polluted U.S. cities
1 Los Angeles-Long Beach-Riverside, CA
2 Visalia-Porterville-Hanford, CA
3 Bakersfield, CA
4 Fresno-Madera, CA
5 Sacramento-Roseville, CA
6 Houston-The Woodlands, TX
7 Modesto-Merced, CA
8 Dallas-Fort Worth, TX
9 Washington-Baltimore-Arlington, DC-MD-VA
10 Las Vegas-Henderson, NV
*Based on a three-year average of the number of days measurements exceeded federal health standards for ozone.Most polluted U.S. cities by short-term particle pollution
1 Fresno-Madera, CA
2 Visalia-Porterville-Hanford, CA
3 Bakersfield, CA
4 Los Angeles-Long Beach-Riverside, CA
5 Modesto-Merced, CA
6 Pittsburgh-New Castle-Weirton, PA, OH, WV
7 Fairbanks, AK
8 Salt Lake City-Provo-Orem, UT
9 El Paso-Las Cruces, TX-NM
10 San Jose-San Francisco-Oakland, CA
* Based on a three-year average of the number of days measurements exceeded federal health standards for fine particle pollution.Source: American Lung Association
