According to EPA, "Acid rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from fossil fuel combustion. The result is a mild solution of sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles.
Information about acid rain, EPA’s Acid Rain Program, and information about relevant laws and regulations is available on EPA’s Web sites.
- EPA’s Acid Rain Home Page
- EPA’s Learn the Issues – Acid Rain – includes information for students, and information about the effects of acid rain on the environment
- EPA’s Clean Air Markets – Acid Rain Program
- Laws and Regulations – Acid Rain