Ozone Pollution

The State of the Air 2012 finds continued progress in cutting ozone pollution in 2008-2010, compared to the 2011 report. Thanks to reductions in emissions from coal-fired power plants and the transition to cleaner cars, the air has gotten much cleaner across the nation. However, millions still breathe too much ozone pollution.

More than 4 in 10 people in the United States (41%) live in areas with unhealthful levels of ozone. Counties that were graded F for ozone levels have a combined population of almost 116.7 million. These people live in the 195 counties where the monitored air quality places them at risk for premature death, coughing, wheezing, asthma attacks, decreased lung function, respiratory infection, lung inflammation and worsened lung diseases. The actual number who breathe unhealthy levels of ozone is likely much larger, since this number does not include people who live in adjacent counties in metropolitan areas where no monitors exist.

  • Twenty-two of the 25 cities with the most ozone pollution improved their air quality over the past year’s report. More than half of the country’s most smog-polluted cities experienced their best year yet—but people living there are still forced to breathe air that reaches dangerous levels. Three cities with the most ozone pollution had worse air quality compared with last year’s report.
  • Of the 25 metropolitan areas most polluted by ozone, eighteen reported their fewest unhealthy ozone days since the State of the Air reports began1: Los Angeles, CA; Visalia, CA; Bakersfield, CA; Sacramento, CA; San Diego, CA; Houston, TX; Dallas-Fort Worth, TX; Washington-Baltimore, DC-MD-VA; El Centro, CA; New York, NY; Charlotte, NC; Phoenix, AZ; Pittsburgh, PA; Birmingham, AL; Cincinnati, OH; Baton Rouge, LA; Philadelphia, PA; and Atlanta, GA. Los Angeles, CA remained the city with the worst ozone pollution problem, but reported its fewest unhealthy ozone days since the State of the Air reports began.

What is ozone?

Ozone is a molecule of three oxygen atoms. Ozone attacks lung tissue by reacting chemically with it. To learn more, go to Health Risks.

» 25 Most Ozone-Polluted Cities
» 25 Cleanest Cities for Ozone

  1. Full names for all these metropolitan areas can be found in the tables showing the most polluted and cleanest cities. The full metropolitan areas often include multiple counties, incorporated cities and counties in adjacent states.

FACT: Cutting air pollution through the Clean Air Act will prevent at least 230,000 deaths and save $2 trillion annually by 2020.

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