On July 20, 2012, the U.S. Court of Appeals for the District of Columbia dismissed in part and denied in part petitions to review the new one-hour SO2 National Ambient Air Quality Standard (NAAQS) of 75 parts per billion (ppb). Several states and state regulatory agencies, together with corporations and industrial associations petitioned for review of the new hourly standard on the ground that EPA: (1) failed to follow notice and comment rulemaking procedures because it did not include in its proposed rule any suggestion that it was considering changing its method of determining attainment of the SO2 standard from a monitoring approach to a hybrid approach using computer modeling in combination with air monitoring, and (2) arbitrarily set the maximum SO2 concentration a level lower than statutorily authorized.

The three judge panel (Sentelle, Kavanaugh, and Ginsburg) held that the challenge to the rulemaking procedure was not within the Court’s jurisdiction because the challenged statements regarding the use of modeling over monitoring did not constitute final action. The language addressing the hybrid modeling/monitoring approach is within the preamble, which is not a final action by definition. The Court noted that the petitioners are free to challenge any final action that EPA takes that imposes such an obligation. The Court further held that EPA did not act arbitrarily in setting the level of SO2 emissions because EPA properly relied on the available evidence. While the Court could not determine that the studies review by EPA necessitated a 75 ppb standard, the Court was unable to say that such a standard is unsupported by the record.