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Acid Rain Program 2006 Progress Report

Published November 2007

Other progress reports

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The Appendicies are Excel spreadsheets. Open them with your installed version of Excel or download a free copy of the Microsoft Excel viewer

Summary of the report results:

The Acid Rain Program was created to implement Title IV of the 1990 Clean Air Act Amendments. The purpose of Title IV is to reduce the adverse effects of acid deposition through reductions in annual emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) by 10 million tons and by 2 million tons below projected levels, respectively.

Sulfur dioxide (SO2) and nitrogen oxides (NOx) are the key pollutants in the formation of acid rain. These pollutants also contribute to the formation of fine particles (sulfates and nitrates) that are associated with significant human health effects and regional haze. Additionally, NOx combines with volatile organic compounds (VOCs) to form ground-level ozone (smog) and nitrates that are transported and deposited at environmentally detrimental levels in parts of the country. These pollutants, in their various forms, lead to the acidification of lakes and streams rendering some of them incapable of supporting aquatic life. In addition, they impair visibility in our national parks, create respiratory and other health problems in people, weaken forests, and degrade monuments and buildings.

In the United States, the electric power industry accounts for approximately 70 percent of total annual SO2 emissions and slightly more than 20 percent of total annual NOxemissions.

Since the start of the Acid Rain Program in 1995, the lower SO2 and NOx emission levels from the power sector have contributed to significant air quality and environmental and human health improvements.

Since its inception, the Acid Rain Program has:

A 2005 study (PDF) (15pp., 532 K) estimates that in 2010, the Acid Rain Program's annual benefits will be approximately $122 billion (2000$), at an annual cost of about $3 billion - a 40-to-1 benefit-to-cost ratio.

The Acid Rain and Related Programs 2006 Progress Report expands on previous year's compliance reports to include special sections on issues related to status and trends in air quality, acid deposition and ecological effects, understanding the suite of Clean Air Rules, emerging issues related to sulfate concentrations, mercury monitoring and anticipated ecological effects of Clean Air rules implementation. Building on the Acid Rain Program model, EPA promulgated the Clean Air Interstate Rule (CAIR) in March 2005, to address transport of fine particles and ozone in the eastern United States, the Clean Air Mercury Rule (CAMR) to reduce nationwide mercury emissions from power plants, and the Clean Air Visibility Rule (CAVR) to improve visibility in national parks and wilderness areas.

SO2 Emissions from Acid Rain Program Sources
Bar chart showing SO2 emissions declining from about 17.3 million tons in 1980 to 9.5 million tons in 2006

Please see the report for more detailed information or higher resolution images



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