Scientists say that a lot of work still remains to be done

Jan 20, 2012 08:17 GMT  ·  By

Scientists with the United States Geological Survey (USGS) say in their latest report to Congress that the incidence of acid rain events throughout the country has been in sharp decline over the past few years. The document, while optimistic, highlights the need for even more action.

The most important efforts to curb the dangerous phenomenon were applied to acid-sensitive lakes and streams, but also to fossil fuel-powered electrical plants. This led to an increase in air quality and visibility, improvements in human health, as well as higher water quality.

All these effects contributed to diminishing the amount of acid rain that used to fall to the ground. The dangerous mixture was responsible for effects ranging from harming people's skins and the faces of statues to destroying forests and negatively-affecting ecosystems.

The report was developed under the guises of the National Acid Precipitation Assessment Program (NPAAP), and is to be presented to Congress soon. The Acid Rain Program was first established under the 1990 Clean Air Act Amendments.

Data compiled by the US Environmental Protection Agency (EPA) also reveals that SO2 and NOx emissions – primarily from power plants that rely on oil, natural gas and coal for electricity production – have been decreasing, mostly due to new laws and regulations.

Despite the good news, many sensitive forests and aquatic ecosystems are not out of the woods yet, since they were brought to the brink when the phenomenon was in full swing. Therefore, scientists highlight the need for continued efforts in all these areas.

“The SO2 [portion of the] program includes the use of a creative emissions cap-and-trade program that combines the best of American science, government, and market-driven innovation,” Dr. John P. Holdren explains.

The official holds an appointment as the director of the US Office of Science and Technology Policy, and is also an assistant to the President for science and technology. He explains that the human health benefits of rarer acid rain events are now valued at $170 to $430 billion per year.

“The principal message of this report is that the Acid Rain Program has worked. The emissions that form acid rain have declined and some U.S. areas are beginning to recover,” adds Doug Burns

“However, some sensitive ecosystems are still receiving levels of acid rain that exceed what is needed for full and widespread recovery. We have every reason to believe that recovery will continue with further decreases in emissions which is why further emission reductions would be beneficial,” he says.

Burns was the lead author on the new report, the director of the NAPAP, and a hydrologist at the USGS.