America's 25 Most Ozone-Polluted Metropolitan Areas, 2014
Updated February 21, 2017 | Factmonster Staff 
Each year the American Lung Association issues their "State of the Air" report. They track year-round and short-term particle pollution as well as the ozone pollution listed here. Though ozone pollution isn't the obvious, sooty kind of pollution, it can still be harmful to your health. Studies have shown that ozone pollution can worsen conditions such as bronchitis, asthma, emphysema, and cardiovascular disease.
| Rank: City |
|---|
| #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 |
| #8: Washington-Baltimore-Arlington, DC-MD-VA-WV |
| #10: Las Vegas-Henderson, NV-AZ |
| #11: Phoenix-Mesa-Scottsdale, AZ |
| #12: New York-Newark, NY-NJ-CT-PA |
| #13: St. Louis-St. Charles-Farmington, MO-IL |
| #14: Tulsa-Muskogee-Bartlesville, OK |
| #14: Cincinnati-Wilmington-Maysville, OH-KY-IN |
| #16: Philadelphia-Reading-Camden, PA-NJ-DE-MD |
| #17: El Centro, CA |
| #18: Louisville-Jefferson County-Madison, KY-IN |
| #19: Oklahoma City-Shawnee, OK |
| #20: Chicago-Naperville, IL-IN-WI |
| #21: Pittsburgh-New Castle-Weirton, PA-OH-WV |
| #22: Fort Collins, CO |
| #23: Birmingham-Hoover-Talladega, AL |
| #24: Sheboygan, WI |
| #25: Cleveland-Akron-Canton, OH |
Source: State of the Air: 2014, American Lung Association.
