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Acid Rain Program 2003 Progress Report

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Congress created the Acid Rain Program in Title IV of the 1990 Clean Air Act Amendments. The Acid Rain Program has the goals of lowering the electric power industry’s annual emissions of:

In 2003, Acid Rain Program emission controls on the electric power industry resulted in:

Figure 1: Trends in SO2 emissions since 1980 for all Title IV affected sources.

S02 Emissions graph

Figure 2: Trends in NOx emissions under the Acid Rain Program.

NOx Emissions graph

As in years past, the electric power industry achieved nearly 100 percent compliance with Acid Rain Program requirements — only 1 unit had emissions exceeding the SO2 allowances that it held and no units were out of compliance with the NOx program. This exceptionally high level of compliance was, in part, achieved as a result of the Acid Rain Program’s continued provision of accurate and complete SO2 and NOx emissions data. This process was augmented by a substantial auditing effort and accountability through rigorous, yet streamlined, reporting systems.

SO2 and 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 health effects and regional haze. Additionally, NOx combines with volatile organic compounds (VOCs) to form ozone (smog), and nitrates that are transported and deposited at environmentally detrimental levels in parts of the country. The United States (U.S.) electric power industry accounts for approximately 67 percent of total annual SO2 emissions and 22 percent of total annual NOx emissions.

Since the Acid Rain Program began in 1995, the lower SO2 and NOx emissions levels from the power sector have contributed to significant air quality and environmental improvements that EPA’s Clean Air Status and Trends Network (CASTNET) and other long-term environmental monitoring networks are reporting.

Over the last decade:

Figure 3
Annual Mean Wet Sulfate Deposition
1989 through 1991

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Annual Mean Wet Sulfate Deposition
2001 through 2003

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Figure 3: Wet sulfate deposition decreased throughout the early 1990s in much of the Ohio River Valley and Northeastern U.S. Other less dramatic reductions were observed across much of New England, portions of the Southern Appalachian Mountains and in the Midwest. Average decreases in wet deposition of sulfate range from 39 percent in the Northeast to 17 percent in the Southeast. Click images to view larger maps.

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