Acid Rain Program Results
The Acid Rain Program (ARP) has delivered significant reductions of sulfur dioxide (SO2) and nitrogen oxides (NOX) emissions from fossil fuel-fired power plants, extensive environmental and human health benefits, and far lower-than-expected costs. Together with more recent power sector regulations, including the Cross-State Air Pollution Rule (CSAPR), and a rapidly changing energy sector, the ARP has helped deliver annual SO2 reductions of over 93% and annual NOX emissions reductions of over 87%. The Power Plant Emissions Trends page has maps and data highlighting these emissions reductions, and the Progress Reports provide an annual overview of program features and results, from compliance to air quality impacts.
Hover left to right over the maps to see the changes before and after.
These emissions reductions have led to major decreases in acid rain nationwide. Wet sulfate deposition – a common indicator of acid rain – dropped by 68% between 1989-1991 and 2017-2019. Additional data and maps detailing deposition and ambient air pollution are available on the Clean Air Status and Trends Network (CASTNET) website.
Hover left to right over the map to see the changes before and after.
Next, learn more about the details of the Acid Rain Program.
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