U.S. Air Quality Improving

The EPA monitors six principal air pollutants for which there are national standards.  The amount of pollution from these air pollutants has dropped significantly in recent decades.  Not that one hears much about this in the mainstream media.  These pollutants include SO2 (sulfur dioxide), NOx (nitrogen oxides), particulate matter, CO (carbon monoxide), ozone, and lead.  Volatile organic compounds (VOCs) are also closely watched.

From 1970 to 2004, emissions of these pollutants declined greatly, especially lead, which dropped by 99%.  Back on 22 September 2004, the EPA announced that emissions of air pollutants had been cut in half since the Clean Air Act was passed in 1970.  Particulate matter was down 81%, VOCs were down 54%, CO was down 53%, SO2 was down 49%, and NOx was down 24%, despite the economy growing 176% during that period.

The declines continue.  SO2 emissions from US power plants fell another 24% for the first half of 2009 compared to the first half of 2008.  NOx emissions were down 5% in May and 11% in June compared to a year earlier.  The EPAs models predict a 70% emissions reduction for cars and trucks over the next 20 years according to the October 2009 issue of Environment & Climate News.