Ten states and several industry organizations, including the American Petroleum Institute (API) and the Independent Petroleum Association of America (IPAA), have filed petitions in federal appellate court challenging the U.S. Environmental Protection Agency’s (EPA) proposed changes to the National Ambient Air Quality Standards (NAAQS).

Last October, the EPA strengthened the NAAQS for ground-level ozone, from 75 parts per billion (ppb) to 70 ppb (see Daily GPI, Oct. 1, 2015). It also strengthened the secondary ozone standard to 70 ppb and extended the ozone monitoring season for 32 states and the District of Columbia. Under the Clean Air Act (CAA), the EPA is required to review the standards every five years; it was last set to 75 ppb in 2008.

But in a legal brief filed last Friday in the U.S. Court of Appeals for the District of Columbia, 10 states — Arizona, Arkansas, Kentucky, Louisiana, New Mexico, North Dakota, Oklahoma, Texas, Utah and Wisconsin — argue that the EPA’s approach to background ozone levels caused by uncontrollable sources violates the CAA.

Specifically, they argue that the EPA “violated the CAA by failing to address adequately the peak effect of uncontrollable emissions on peak days,” and by “impermissibly adopting non-textual limitation on its own authority.” The states also said EPA’s “promised enforcement relief measures are impractical and misuse portions of the CAA intended for exceptional rather than routine events.”

The states also argued that the EPA’s methods would lead to a NAAQS review process that would lack an “intelligible principle,” and that the agency’s reliance on a single clinical study — also known as the Schelegle study, which was conducted in 2009 — to justify a new NAAQS is “arbitrary and capricious.”

“EPA’s hastily-crafted ozone NAAQS imposes an unachievable standard, divorced from the scientific realities of background ozone,” the states said. “The agency’s only response is to promise a partial accommodation that the statute limits in both applicability and degree of relief. This model of rulemaking does not accord with the CAA, which demands that NAAQS be achievable.”

API, IPAA and other industrial groups — including the National Association of Manufacturers and the American Fuel & Petrochemical Manufacturers — filed a separate, similar brief last Friday.

“This court should vacate the revised NAAQS and remand them to EPA for consideration of their achievability in light of background ozone concentrations and establishment of NAAQS at a level that is achievable given background concentrations; consideration of the adverse economic, social, and energy impacts of the standards; and a reasoned explanation for any change in EPA’s conclusions from the scientific effects evidence,” the industrial groups said.

Several environmental groups also filed briefs last Friday challenging the EPA, but for different reasons. The groups — the Sierra Club, Physicians for Social Responsibility, the National Parks Conservation Association, the Appalachian Mountain Club, and West Harlem Environmental Action, Inc. — argue that the EPA acted unlawfully when it adopted “an ozone health standard that allows multiple days each year where ozone air pollution exceeds levels that EPA itself found cause adverse health effects,” among other reasons.

Under the CAA, states must meet the new 70 ppb limit between 2020 and 2037, based on ozone levels in the area.

The case is Murray Energy Corp. v. EPA [No. 15-1385].