Acid Rain Program 2004 Progress Report
You will need Adobe Acrobat Reader to view some of the files on this page. See EPA's About PDF page to learn more about PDF, and a link to the free Adobe Acrobat Reader.
- 2004 Progress Report (PDF) (30 pp., 2 MB)
- Appendix A (Excel, 100 K) | Appendix A (PDF) (90 pp, 260 KB)
- Appendix B1 (Excel, 20 K) | Appendix B1 (PDF) (22 pp, 58 K)
- Appendix B2 (Excel, 19 K) | Appendix B2 (PDF) (19 pp, 24 K)
In 1990, Congress established the Acid Rain Program under the Clean Air Act. The principal goal of the program is to achieve reductions of 10 million tons of sulfur dioxide (SO2) and 2 million tons of nitrogen oxides (NOx), the primary components of acid rain. 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.
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. In the United States, the electric power industry accounts for nearly 70 percent of total annual SO2 emissions and slightly more than 20 percent of total annual NOx emissions.
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 SO2 and NOx by 10 million tons and by 2 million tons below projected levels, respectively.
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.
The 2004 compliance year marked the 10th year of the program. During that period, the Acid Rain Program has:
- Reduced SO2 emissions by over 5 million tons from 1990 levels, or about 34 percent of total emissions from the power sector. Compared to 1980 levels, SO2 emissions from power plants have dropped by 7 million tons, or more than 40 percent.
- Cut NOx emissions by about 3 million tons from 1990 levels, so that emissions in 2004 were less than half the level anticipated without the program. Other efforts, such as the NOx Budget Trading Program in the eastern United States, also contributed significantly to this reduction.
- Led to significant cuts in acid deposition, including reductions in sulfate deposition of about 36 percent in some regions of the United States and improvements in environmental indicators, such as fewer acidic lakes.
- Provided the most complete and accurate emission data ever developed under a federal air pollution control program and made that data available and accessible by using comprehensive electronic data reporting and Web-based tools for agencies, researchers, affected sources, and the public.
- Served as a leader in delivering e-government, automating administrative processes, reducing paper use, and providing online systems for doing business with EPA.
- Resulted in nearly 100 percent compliance through rigorous emissions monitoring, allowance tracking, and an automatic, easily understood penalty system for noncompliance. Flexibility in compliance strategies reduced implementation costs.
A 2005 study 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.
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.
This report describes progress made by the Acid Rain Program to address this environmental problem. It provides both basic information about the nature of acid deposition and detailed descriptions of how key indicators have changed.