America's 25 Most Ozone-Polluted Metropolitan Areas, 2007
Updated February 21, 2017 | Factmonster Staff 
Ozone acts as a powerful respiratory irritant at the levels frequently found in most of the nation's urban areas during summer months. Symptoms include shortness of breath, chest pain when inhaling deeply, wheezing, and coughing. A study of a sample of longtime residents of Los Angeles, which has the highest and most frequent ozone problem in the nation, found that the group had a higher-than-expected loss of lung function over time.
| Rank | City |
|---|---|
| 1. | Los Angeles-Long Beach-Riverside, Calif. |
| 2. | Bakersfield, Calif. |
| 3. | Visalia-Porterville, Calif. |
| 4. | Fresno-Madera, Calif. |
| 5. | Houston-Baytown-Huntsville, Tex. |
| 6. | Merced, Calif. |
| 7. | Dallas-Fort Worth, Tex. |
| 8. | Sacramento--Arden-Arcade--Truckee, Calif.-Nev. |
| 9. | Baton Rouge-Pierre Part, La. |
| 10. | New York-Newark-Bridgeport, N.Y- N.J.-Conn.-Pa. |
| 11. | Washington-Baltimore-Northern Virginia, DC-Md.-Va.-W.Va. |
| 12. | Philadelphia-Camden-Vineland, Pa.-N.J.-Del.-Md. |
| 13. | Hanford-Corcoran, Calif. |
| 13. | Modesto, Calif. |
| 15. | Phoenix-Mesa-Scottsdale, Ariz. |
| 16. | Charlotte-Gastonia-Salisbury, N.C.-S.C. |
| 17. | Las Vegas-Paradise-Pahrump, Nev. |
| 17. | Milwaukee-Racine-Waukesha, Wis. |
| 19. | St. Louis-St. Charles-Farmington, Mo.-Ill. |
| 20. | El Centro, Calif. |
| 20. | Kansas City-Overland Park-Kansas City, Mo.-Kans. |
| 20. | Beaumont-Port Arthur, Tex. |
| 20. | Chicago-Naperville-Michigan City, Ill.-Ind.-Wis. |
| 24. | Grand Rapids-Muskegon-Holland, Mich. |
| 25. | Atlanta-Sandy Springs-Gainesville, GA-Ala. |
| 25. | Cleveland-Akron-Elyria, Ohio |
Source: State of the Air: 2007, American Lung Association.
