The U.S. Court of Appeals for the District of Columbia Circuit has upheld the U.S. Environmental Protection Agency’s (EPA’s) national ambient air quality standard (NAAQS) for nitrogen dioxide (NO 2). Am. Petroleum Inst. v. EPA, No. 10-1079 (D.C. Cir. 7/17/12). The February 2010 rule set the one-hour maximum NAAQS at 100 parts per billion. 75 Fed. Reg. 6474 (2/9/10).  

Petitioners challenged the rule, arguing that EPA’s process for adopting the standard was flawed and resulted in a standard more stringent than necessary to protect public health. They also argued that EPA discounted a study disputing the agency’s conclusion, relied on non-peer-reviewed studies, treated the same study differently in reviews of nitrogen oxide and ozone, and made faulty assumptions in projecting air quality benefits. Petitioners claimed that EPA’s adoption of the rule was arbitrary and capricious under the Administrative Procedure Act (APA) and violated the Clean Air Act (CAA) because the agency violated its own requirements that it rely on published, peer-reviewed studies when reviewing NAAQS.  

The unanimous three-judge panel said the EPA rule was neither arbitrary nor capricious, did not violate the CAA and that EPA’s procedure complied with the APA. On the claim that EPA violated its own requirements by not relying on peer-reviewed studies, the court said petitioners were simply incorrect and that peer review is left to “the discretion of agency management.”