The EPA yesterday issued a final rule for sulfur dioxide (SO2) limits under the Clean Air Act. The new rule establishes a new one-hour standard at 75 parts per billion (ppb). In addition, the EPA is revoking the current 24-hour and annual SO2 primary standards because, according to the EPA, those standards do “not provide additional health benefits.” The two existing standards were 140 ppb evaluated over 24-hours, and 30 ppb evaluated over an entire year.

The new rule also creates new monitoring requirements, such as placing monitors in more populated areas. Specifically, the regulations require monitors to be placed in Core Based Statistical Areas (CBSAs) based on population weighted emissions index for the area.  Those requirements take place January 1, 2013.

To learn more about the new SO2 standards, click here.