D.C. is credited with being one of the greenest cities, one of the healthiest cities and one of the wealthiest cities. But it\'s also one of the most polluted cities.

WASHINGTON — D.C. is credited with being one of the greenest cities, one of the healthiest cities and one of the wealthiest cities. But a report issued this week shows it’s also one of the most polluted cities.

The 2014 State of the Air report, released by the American Lung Association, ranks the D.C. area eighth out of 277 metropolitan areas for high-ozone days. The Los Angeles area ranked first.

The U.S. Environmental Protection Agency tells WTOP ozone levels in the country decreased 14 percent between 1990 and 2012. Even so, D.C. just moved up on the most ozone-polluted cities list. In 2013, it ranked ninth; in 2012 it was 13th.

Ground-level ozone, also known as smog, is formed by a chemical reaction that happens when air pollutants, such as those found in vehicle exhaust or factory emissions, react with sunlight.

Leyla McCurdy, senior director of health and environment at the National Environmental Education Foundation, says high ozone levels affect our health, and especially our lungs. This is because ozone is not very water-soluble and thus acts as an irritant to lung tissue when it is inhaled, the EPA says.

“Especially for people who have asthma, high ozone days are extremely unhealthy,” McCurdy says.

Of the 9,331,587 people in the defined area of Washington, Baltimore and Arlington, 213,933 children and 651,339 adults have asthma, the ALA says in its report .

Asthma is not the only health effect of ozone. The EPA says high ozone levels are associated with respiratory inflammation, increased hospital admissions and increased daily mortality. Ozone also threatens the health of those with cardiovascular disease, chronic obstructive pulmonary disease and diabetes, the ALA says.

Jim Dougherty, a member of the board of directors for the Sierra Club, says several things can be done to improve the quality of air in the D.C. area. For starters, he says, officials should take a closer look at big sources of pollution, such as coal-burning power plants.

Re-thinking transportation should be another priority, he says.

“This is largely about cars and trucks … The city has made great strides in the last 12 years on promoting pedestrian options and bike paths. And you’ve seen a lot more people in bikes. What we really need to do is get people out of their cars, eliminate free parking and get onto buses and Metro.”

He says the government needs to set stricter rules on emissions as well. The Obama Administration is expected to release rules on carbon dioxide emissions for power plants in 30 days, and Dougherty says the strength of that package will have a lot to do with having clean air.

Dougherty says, “Isn’t it a sad commentary that in the year 2014, 44 years after passing the Clean Air Act, that we still don’t have air in the city that’s safe to breathe?”

The EPA released the following statement to WTOP when asked about the impact of ozone on a city and ways it can be prevented or controlled:

“EPA shares ALA’s concerns about air quality, and the agency is committed to reducing air pollution to protect public health. The Clean Air Act has helped us make remarkable progress in protecting the air we breathe, but we have more to do. The agency continues to work to reduce harmful pollution and protect the health of families across the United States. For example, in March 2014, EPA finalized cleaner fuel and car standards that will yield between $6.7 billion to $19 billion in benefits annually, through reducing health effects such as premature deaths, heart attacks, asthma attacks and hospital and emergency room visits.”

The 10 Most Polluted Cities By Ozone:

Los Angeles-Long Beach, Calif. Visalia-Porterville-Hanford, Calif. Bakersfield, Calif. Fresno-Madera, Calif. Sacramento-Roseville, Calif. Houston-The Woodlands, Texas Modesto-Merced, Calif Washington-Baltimore-Arlington, D.C., Md., Va. Dallas-Fort Worth, Texas Las Vegas-Henderson, Nev., Ariz.

The 10 Most Polluted Cities By Year Round Particle Pollution:

Fresno-Madera, Calif. Visalia-Porterville-Hanford, Calif. Bakersfield, Calif. Los Angeles-Long Beach, Calif. Modesto-Merced, Calif. Pittsburgh-New Castle-Weirton, Pa. Ohio, W.Va. El Centro, Calif. El Paso-Las Cruces, Texas, N.M. St. Louis-St. Charles-Farmington, Mo., Ill. Phoenix-Mesa-Scottsdale, Ariz.

The 10 Most Polluted Cities By Short-Term Particle Pollution:

Fresno-Madera, Calif. Visalia-Porterville-Hanford, Calif. Bakersfield, Calif. Los Angeles-Long Beach, Calif. Modesto-Merced, Calif. Pittsburgh-New Castle-Weirton, Pa. Ohio, W.Va. Fairbanks, Alaska Salt Lake City-Provo-Orem, Utah El Paso-Las Cruces, Texas, N.M. San Jose-San Francisco-Oakland, Calif.

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