Nation's Air Improving, Even in L.A.

Air Quality in Most Polluted Cities Is Best in Over a Decade, Report Finds

Medically Reviewed by Laura J. Martin, MD on April 24, 2012
From the WebMD Archives

April 25, 2012 -- People who live in the nation's most polluted cities are breathing cleaner air than they have in over a decade, according to new data released today by the American Lung Association (ALA).

The group's annual "State of the Air" report highlights successes in lowering pollution levels across the nation while mentioning the ALA's struggles to maintain federal laws aimed at protecting the air Americans breathe.

"We have seen continued progress in cleaning up air pollution across the nation, but more than 127 million people still live in places that have unhealthy air," says ALA National Policy Advisor Janice Nolen.

Air Cleaner in L.A., Other Cities

The ALA ranks cities on three separate lists: most bouts of short-term particle pollution, most year-round particle pollution, and ozone pollution.

Southern and Central Californians in key counties continue to be exposed to highest levels of particle pollution and smog (ozone), but Nolen says air quality has improved dramatically in many areas of the state.

Los Angeles remained the city with the worst ozone levels, but in 2010 L.A. reported its fewest unhealthy ozone days since the first annual report was issued 13 years ago.

And the city is no longer tops in the nation for highest year-round and short-term particle pollution levels. That dubious honor now belongs to Bakersfield, Calif., with Los Angeles ranking third and fourth in those two categories, respectively.

"I would have expected Los Angeles to continue to top all these lists, but the city has been moving down in recent years," Nolen says.

The ALA report credits the federal Clean Air Act for cleaning up coal-fired power plants and reducing emissions from diesel-engine vehicles and SUVs.

Despite the improvements, ALA President Charles D. Connor called existing air quality standards "woefully outdated" in a statement, noting that millions of Americans are still exposed to unhealthy air every day.

Santa Fe Has Best Air

The report identified the 25 cities with the highest and lowest levels of smog and particle pollution, or soot, which is a dangerous mix of microscopic ash, diesel exhaust, chemicals, metals, and aerosols. (Full lists can be found below.)

Particle pollution is considered the most dangerous common air pollutant in the U.S.

Among the report's major findings:

  • Eighteen of the nation's smoggiest cities, including Los Angeles, experienced ozone reductions.
  • Seventeen of the 25 most polluted cities, including L.A., Pittsburgh, and Cincinnati, had their lowest particle pollution levels in the history of the annual report.
  • For the first time in over a decade, Birmingham, Ala., Detroit, and York, Pa., were no longer among the 25 most polluted cities.
  • Santa Fe, N.M., topped the list of the nation's cleanest cities, followed by Cheyenne, Wyo., and Prescott and Tucson, Ariz.

4 in 10 Americans Live With Dangerous Air

Despite the improvements, nearly 50 million Americans live in counties with unhealthy spikes in particle pollution levels:

  • Roughly 4 in 10 people in the U.S. are exposed to unhealthy levels of smog or particle pollution year-round or at various times during the year.
  • Nearly 2.5 million children and 7.4 million adults with asthma live in parts of the United States with very high ozone levels, and more than 3 million adults and close to 1 million children with asthma live in areas with high levels of short-term particle pollution.
  • More than 11 million adults with heart disease and 3 million with diabetes live in areas with high levels of short-term particle pollution.

The Rest of the Best -- and Worst

Cleanest Cities in the U.S. - Lowest Year-Round Particle Pollution

  1. Santa Fe, N.M.
  2. Cheyenne, Wyo.
  3. Prescott, Ariz.
  4. Tucson, Ariz.
  5. Albuquerque, N.M.
  6. Redding, Calif.
  7. Colorado Springs, Colo.
  8. Flagstaff, Ariz.
  9. Anchorage, Alaska
  10. Boise City, Idaho

10 Areas With the Most Year-Round Particle Pollution

  1. Bakersfield-Delano, Calif.
  2. Hanford-Corcoran, Calif.
  3. Los Angeles-Long Beach-Riverside, Calif.
  4. Visalia-Porterville, Calif.
  5. Fresno-Madera, Calif.
  6. Pittsburgh-New Castle, Pa.
  7. Phoenix-Mesa-Glendale, Ariz.
  8. Cincinnati-Middletown-Wilmington, Ohio-Ky.-Ind.
  9. Louisville-Jefferson County-Elizabethtown-Scottsburg, Ky.-Ind.
  10. Philadelphia-Camden-Vineland, Pa.-N.J.-Del.-Md.

10 Most Ozone-Polluted Areas

  1. Los Angeles-Long Beach-Riverside, Calif.
  2. Visalia-Porterville, Calif.
  3. Bakersfield-Delano, Calif.
  4. Fresno-Madera, Calif.
  5. Hanford-Corcoran, Calif.
  6. Sacramento-Arden-Arcade-Yuba City, Calif.-Nev.
  7. San Diego-Carlsbad-San Marcos, Calif.
  8. Houston-Baytown-Huntsville, Texas.
  9. San Luis Obispo-Paso Robles, Calif.
  10. Merced, Calif.

To see where your community ranks on the list, check out

Show Sources


American Lung Association: "State of the Air 2012 Report."

Janice Nolen, National Policy Adviser and "State of the Air" project director, American Lung Association.

Charles D. Connor, president and CEO, American Lung Association.

News release, American Lung Association.

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