[JURIST] The US Court of Appeals for the District of Columbia Circuit [official website] on Tuesday dismissed petitions by the American Petroleum Institute [advocacy website] that challenged recently enacted Environmental Protection Agency (EPA) [official website] regulations restricting the peak amount of nitrogen dioxide (NO₂) [EPA backgrounder] from tailpipes and smokestacks that can remain in the air for a one-hour period. The three-judge panel ruled [opinion, PDF] that the API, which represents more than 500 oil and gas companies, had failed to prove that the EPA’s 2010 adoption of a more stringent one-hour national ambient air quality standard (NAAQS) [materials] for NO₂ was “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law” as required by the Clean Air Act (CAA) [official website; EPA backgrounder]. According to the API, the EPA was arbitrary and capricious in how it dealt with the record evidence in developing the NAAQS, set at a a one-hour standard of 100 parts per billion, and the NAAQS it adopted is unlawful because it is more stringent than is “requisite to protect the public health” with “an adequate margin of safety” as mandated by the CAA:

The API claims the process by which the EPA adopted the new NAAQS was flawed and the standard must therefore be vacated. More specifically, it faults the EPA for (1) relying upon an unpublished, non-peer-reviewed meta-analysis of clinical studies, (2) discounting a published meta-analysis that called into question the EPA’s conclusions, (3) treating the same epidemiological study differently in reviews of the NAAQS for NO₂ and for ozone, and (4) projecting the benefits to air quality from the new NAAQS based upon faulty assumptions.

The court found that the EPA has a “duty to err on the side of caution” and dismissed the API complaint, concluding that the EPA did not act unreasonably in formulating the NAAQS. There has not been a new NAAQS adopted for NO₂ in at least 35 years, and previously there had been no one-hour rule for NO₂, unlike the current time-based restrictions on carbon monoxide and ozone. NO₂ is a toxic gas [Bloomberg report] that contributes to smog and has been tied to respiratory problems, especially in people with asthma, according to the EPA.

The EPA is vested with the authority [JURIST report] under the CAA to regulate the emission of greenhouse gases, such as carbon dioxide, by automobiles. In Massachusetts v. EPA [Duke Law case backgrounder; JURIST report], 12 states and several environmental groups sued the EPA arguing that the agency had “abdicated its responsibility under the Clean Air Act” to regulate greenhouse gas emissions. The court held that greenhouse gas was within the CAA’s definition of “air pollutant” and thus, the EPA had statutory authority to take control the emission of such gases from new motor vehicles.