America's Most Polluted Cities

This Wired Article lists the 10 most polluted cities and mentions that off-road vehicles, trucks, buses and diesel powered vehicles are major contributors to our air pollution problems. By 2010 these vehicles must meet new emission guidelines that should reduce their emissions by 95% (if guidelines aren't rolled back). China and Mexico continue to be big pollution sources as they do our industrial dirty work. California takes 6 of the top 7 spots in the list.
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