After a careful review of the best available science, the U.S. Environmental Protection Agency (EPA) is proposing secondary air quality standards to protect the environment from nitrogen oxides (NOx) and sulfur oxides (SOx). Today’s proposal builds on EPA efforts already underway to reduce NOx and SOx emissions.
EPA has made significant progress in developing a multi-pollutant standard that would protect vulnerable ecosystems, including streams and lakes. To ensure any updated standard is effective, EPA is planning to conduct a field pilot program to collect and analyze additional data and information.
In the meantime, EPA is proposing to set an additional secondary standard for each pollutant. The new standards would be identical to the public health standards that the agency strengthened last year. These standards reduce the amount of NOx and SOx in the air and the harmful effects that the pollutants have on sensitive lakes and streams. EPA is also proposing to retain the existing secondary standards for each pollutant.
EPA is already taking a number of steps to reduce NOx and SOx emissions, including the recently announced Cross-State Air Pollution Rule. This new rule will cut millions of tons of these pollutants from power plants each year.
Nitrogen oxides are emitted from an array of sources, including vehicles, power plants, off-road equipment, and agricultural sources. Sulfur oxides are emitted from fossil fuel combustion by power plants, large industries, and mobile sources, and from some industrial processes.
EPA will accept comments for 60 days after the proposed rule is published in the Federal Register and will issue a final rule by March 2012.
More information on the proposal is available on the EPA website.