The American Lung Association has released its 2011 State of the Air report. The 12th annual report measures air quality across the United States and lists America’s most polluted cities. This year’s report, for the first time, enables readers to see how their cities rank and how the air has improved—or not—over the years.

The American Lung Association analyzes data from state air quality monitors to compile the report. The report assigns grades for two different types of air pollution—ozone (smog) and particle pollution (soot).

The top five most polluted metropolitan areas in terms of ozone pollution are found in California: Los Angeles-Long Beach-Riverside, Bakersfield-Delano, Visalia-Porterville, Fresno-Madera, Sacramento–Arden-Arcade–Yuba City. Honolulu, Hawaii; Fargo-Wahpeton, ND-Minn; Rochester, Minn; Santa Fe-Espanola, NM; Bismark, ND, regions ranked as the top five cleanest US cities for ozone air pollution.

Four of the top five most polluted metropolitan areas by year round particle pollution are also found in California: Bakersfield-Delano, Los Angeles-Long Beach-Riverside, Visalia-Porterville, Hanford-Corcoran. The Phoenix-Mesa-Glendale, Ariz, area rounds out the top five. Cheyenne, Wyo; Santa Fe-Espanola, NM; Tucson, Ariz; Honolulu, Hawaii,;and Great Falls, Mont, areas ranked as the top five cleanest US cities for year-round particle pollution.

Source: American Lung Association