The D.C. Circuit denied petitions challenging EPA's one-hour primary NAAQS for nitrogen dioxide (NOx). The new one-hour primary NAAQS requires that “the three-year average of the annual 98th percentile of the daily maximum one-hour average concentration be less than or equal to 100 parts per billi...

The D.C. Circuit dismissed petitions challenging EPA's primary NAAQS for sulfur dioxide (SO2). The petitioners—several states, state regulatory agencies, corporations, and industrial associations—argued that EPA failed to follow the APA's notice-and-comment rulemaking procedures because it did n...

A California appellate court upheld a local air district rule that requires manufacturers of consumer paint thinner and solvent products to limit the use of ozone-forming volatile organic compounds (VOCs) in their products. The district issued to rule to satisfy its federal CAA commitments. A pa...

The California Supreme Court upheld an air district's technology-forcing rules that limit certain pollution-causing substances in paints and coatings. A paint association argued that the air district failed to show that technology necessary to meet the emissions limits set by the 2002 amendments...

The D.C. Circuit upheld four EPA rulemakings governing greenhouse gases. EPA issued the rules following the U.S. Supreme Court's decision in Massachusetts v. EPA, 549 U.S. 497 (2007), in which the Court clarified that greenhouse gases meet the definition of an air pollutant under the CAA. Petit...