On Monday, November 16, 2009, the U.S. Environmental Protection Agency (“EPA”) proposed more stringent air quality standards for sulfur dioxide (SO2) in an effort to provide additional protection to public health. The proposal focuses on short-term exposures to peak SO2 levels, and would establish a new national one-hour standard at between 50 and 100 ppb.
The current primary air quality standards for SO2 are annual and 24-hour standards that do not account for short term peaks, and are set at 30 ppb and 140 ppb, respectively. Because EPA believes that a new 24-hour standard between 50 and 100 ppb would be as protective of public health as the current primary standards, the proposed rule would revoke the current annual and 24-hour SO2 health standards. It would also increase SO2 monitoring and reporting requirements, particularly in areas with high SO2 levels and urban areas.
If adopted, the move will be the first time since 1971 that EPA has strengthened the SO2 air quality standard for the purpose of protecting public health. Some industry observers are concerned that the proposed one-hour standard could be set at a level so strict that it will become the primary driver for Clean Air Act compliance requirements for SO2 reductions for electric generating units.
Public comment on the proposal will be received for sixty days after publication in the Federal Register. A public hearing is scheduled for January 5, 2010 in Atlanta, Georgia, and final standards are expected to be issued by June 2010.