"The nation's 25 most smoggy cities improved air quality over the last year, but half the nation's residents still live with unhealthy levels of air pollution, according to an American Lung Association report released on Wednesday.

Weighing the pluses and minuses in U.S. air quality over the past year, the "State of the Air 2011" report concluded that the U.S. Clean Air Act, the federal law aimed at limiting pollution in the nation's skies, is working.

"The progress the nation has made cleaning up coal-fired power plants, diesel emissions and other pollution sources has drastically cut dangerous pollution from the air we breathe," Lung Association President Charles Connor said in a statement."

Barbara Goldberg reports for Reuters April 28, 2011. [2]

ALA Report [3]

"Half of All Americans Breathe Polluted Air" (ENS) [4]