What are America's Most Polluted Cities?

Remember the fog that lingered over Beijing during the 2008 Summer Olympics? It wasn't fog. It was dirty air. Yes, China faces a world-class air quality problem. But before you get too smug about its smog, consider this: 154.5 million Americans, just over half the nation's population, live in areas where air pollution levels are often dangerous to breathe. That's according to the American Lung Association's (ALA) just-released report 2011 State of the Air. The cities ranked worst in air...Full Story