On March 18, the Utility Air Regulatory Group, the PM NAAQS Coalition, and the U.S. Chamber of Commerce sued the Environmental Protection Agency (EPA) in the U.S. Court of Appeals for the District of Columbia Circuit over fine particulate matter air quality standards. On the same day, the U.S. Chamber of Commerce, the Utility Air Regulatory Group (UARG), and seven other organizations petitioned the EPA to reconsider the new standard of 12 micrograms per cubic meter rule.