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Acid Rain Program Maintains Air Pollution Cuts, EPA Reports

Release Date: 10/26/2005
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Contact: Eryn Witcher, 202-564-4355 /

(Washington, D.C.-October 26, 2005) In its 10 years the Acid Rain Program has significantly reduced acid deposition in the United States by cutting sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions from power plants, according to the program's annual report. The newly released Acid Rain Program 2004 Progress Report describes the environmental advances and public health, technology, and market-based improvements accomplished by the program. Widely acknowledged as one of the most successful environmental programs in U.S. history, the program serves as a model for a new generation of air pollution control programs, such as the Clean Air Interstate Rule, which will further reduce air pollution over the next decade.

"Skeptics of innovative market-based solutions need only look at the phenomenal results achieved by the Acid Rain Program," said EPA Administrator Stephen L. Johnson. "By harnessing the power of the markets, President Bush's Clear Skies legislation will create permanent, substantial reductions in soot, smog and mercury pollution, and help ensure that energy costs remain stable and affordable."

In 2004, electric power generation sources reduced their annual SO2 emissions by about 34 percent - a decrease of over 5 million tons when compared to 1990 levels. Compared to 1980 levels, SO2 emissions from power plants have dropped by 7 million tons, or more than 40 percent. NOx emissions were down by about 3 million tons since 1990 and had decreased to nearly half the level anticipated without the Acid Rain Program. Other NOx regulations that also affect power plants, such as the NOx Budget Trading Program in the eastern United States, also contributed to this reduction.

The key environmental driver for the Acid Rain Program is a mandatory 8.95 million ton cap on SO2 emissions. The Program allows sources to buy and sell "allowances" (statutory authorizations to emit SO2). By reducing emissions early, sources can save (or bank) allowances and use them to cover excess emissions in years when the energy demand is higher. Thus, annual fluctuations in SO2 emissions are expected, but the total amount of emissions over the course of the program is fixed and will not increase. In addition, a source's emissions may not exceed National Ambient Air Quality Standards at any time.

Overall compliance with the Acid Rain Program has been consistently high -- nearly 100 percent. In 2004, only four units out of the 3,391 electricity-generating units did not hold enough allowances to cover their emissions. These sources were assessed an automatic penalty of $2,963 per ton for each of the 465 tons of SO2 emitted in excess of allowances, totaling a fine of $1.4 million. In addition, 465 allowances were taken from sources' accounts to ensure that there would be no net increase in emissions.

These emission reductions have led to significant cuts in acid deposition. There have been reductions in sulfate deposition by about 36 percent in some regions of the United States and improvements in environmental indicators such as fewer acidic lakes. In 2004, sulfur dioxide and sulfate concentration levels in atmospheric deposition (key indicators of acid rain) continued to be approximately 30 percent less than pre-Acid Rain Program levels. Levels were cut by even greater amounts, approximately 50 percent, in certain areas. The emission reductions to date have resulted in reduced formation of fine particles, improved air quality, and ecosystem protection.

A new analysis in the Journal of Environmental Management estimates the value of the program's human health and environmental benefits in the year 2010 to be $122 billion annually. Most of these benefits result from the prevention of health-related impacts, such as premature deaths and illnesses and workdays missed due to illness, but they also include improved visibility in parks and other recreational and ecosystem improvements.

The Acid Rain Program has provided the most complete and accurate emissions data ever developed under a federal air pollution control program, and it made that data available and accessible for agencies, researchers, affected sources, and the public by using comprehensive electronic data reporting and Web-based tools. The program is recognized as a leader in delivering e-government, automating administrative processes, reducing paper use, and providing online systems for doing business with EPA. The program has resulted in nearly 100 percent compliance through rigorous emissions monitoring and allowance tracking, and an automatic, easily-understood penalty system for noncompliance.

The progress report details all of this information and includes emission data, SO2 allowance information for electric power plants, and monitored acid deposition levels across the United States. The report is available online at: