Sulfur Dioxide News

Consent Decree issued to address SO2 Designations - On March 2, 2015, the U.S. District Court for the Northern District of California granted the joint motion between the Sierra Club and the U.S. EPA to resolve claims regarding the Agency's failure to promulgate designations for the 2010 revised primary SO2 NAAQS (Case No. 13-cv-03953-SI).

Under the Consent Decree, the EPA would follow a round of designations proposed in the Data Requirements Rule. In addition, they would also be obligated to conduct an earlier round of designations no later than 16 months from the Court's entry of the Consent Decree for areas that have newly monitored violations of the 1-hour SO2 standard or that have coal-fired power plants that in 2012 emitted either more than 16,000 tons of SO2, or emitted more than 2,600 tons of SO2 and had an emission rate of at least 0.45 lbs SO2/MMBtu.

On March 3, 2015, the Judge entered the Consent Decree, beginning the 16 month deadline for the next round of SO2 designations. Thus, the date for this round of designations would be July 2, 2016. The Consent Decree as ordered can be viewed at:

On August 10, 2015, the EPA signed the Data Requirements Rule for the 2010 SO2 NAAQS. More information can be found at: data requirements rule.

On May 13, 2014, the EPA published the proposed "Data Requirements Rule for the 1-Hour Sulfur Dioxide (SO2) Primary National Ambient Air Quality Standard." This rule describes criteria for identifying the sources around which air agencies would need to characterize SO2 air quality.


Mary Peyton Wall, Manager, (803) 898-4064