In 2006, annual SO2 emissions from acid rain program electric power generation sources fell sharply, with reductions of 830,000 tons from 2005 levels and an overall reduction of 40 percent from 1990 levels. NOx emissions were down by over 3 million tons since 1990 and had decreased to nearly half the level anticipated without the Acid Rain Program. These reductions have led to a significant decrease in acid deposition, resulting in improved water quality in U.S. lakes and streams. Reduced formation of fine particles, improved air quality and human health related benefits are all results from the reduction of these emissions.
Since 1995, the market-based cap and trade program has significantly reduced acid deposition in the United States by decreasing sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions. The program's rigorous emissions monitoring and allowance tracking has resulted in nearly 100 percent compliance with the program.
The Acid Rain and Related Programs Progress Report includes emissions, allowance market and compliance data, status and trends in acid deposition, air quality and ecological effects, and information on implementation of the Clean Air Interstate Rule, which will further reduce SO2 and NOx emissions by about 70 percent and 60 percent respectively from 2003 levels.