D.C. Circuit Vacates Parts of EPA Ozone Regulations

The D.C. Circuit last week struck down parts of an Environmental Protection Agency (EPA) rule concerning implementation of its 2008 ozone standards, creating new regulatory limbo for the entities required to comply with the rule.

Ruling in a set of cases consolidated under South Coast Air Quality Management District v. EPA (No. 15-1115), the federal court vacated nine aspects of the EPA's March 2015-promulgated rule governing state implementation of National Ambient Air Quality Standards (NAAQS) for ozone set in 2008.

Significantly, the court unanimously ruled that the EPA unlawfully waived statutory attainment deadlines associated with the EPA's 1997 ozone NAAQS, which the agency revoked in the 2015 rule. Among other aspects, the court also vacated the agency's removal of New Source Review and conformity controls for "orphan nonattainment areas," which are states not required to adopt requirements under the revoked 1997 standards.

An Evolving Rule with Backsliding Issues

The EPA is required by the Clean Air Act (CAA) to set NAAQS for air pollutants to protect public health. The law also requires the EPA to establish air quality control regions and designate them as "attainment" for areas that comply with the NAAQS, and "nonattainment" for areas that don't.

Under the CAA, states bear primary responsibility for assuring air quality, requiring them to submit state implementation plans (SIPs) that specify how they will achieve and maintain compliance with the NAAQS. SIPs for ozone nonattainment areas, specifically, must also provide for implementation of "reasonably available control measures."

Significantly, the CAA also requires the EPA to complete a thorough review of each NAAQS every five years, and if the agency relaxes a NAAQS, the law holds that the EPA must promulgate "anti-backsliding measures" for all areas that have not attained that standard as of the date of the relaxation. Those measures, specifically, must provide for controls that are more stringent than controls that could be applied to nonattainment areas before the relaxation.

Since the EPA promulgated the first ozone NAAQS in 1979-which was based on a one-hour average concentration of 0.12 parts per million (ppm)-the rule has been modified extensively. In 1997, the Clinton administration determined that the one-hour NAAQS was inadequate to protect public health, and the EPA issued a new NAAQS based on an 8-hour average of 0.08 ppm. But though the EPA replaced the one-hour NAAQS with the 8-hour NAAQS, it continued to require that areas attain air quality standards that met the one-hour standard.

In 2004, the Bush administration then moved to revoke the one-hour standard-a move that held up in the D.C. Circuit, though the court required the EPA to introduce and implement "adequate" anti-backsliding provisions. However, in March 2008, the Bush administration determined that the 1997 NAAQS was inadequate to protect public health, and promulgated a new, more stringent NAAQS of 0.075 ppm of ozone averaged over eight hours.

And seven years later, in March 2015, the Obama administration finalized a rule that revised existing rules and guidance to aid implementation of the 2008 ozone NAAQS. That rule-"Implementation of the 2008 National Ambient Air Quality Standards (NAAQS) for Ozone: State Implementation Plan (SIP) Requirements"-was the focus of the D.C. Circuit's decision on Friday. It essentially revoked the 1997 NAAQS, though it added anti-backsliding requirements for areas still in nonattainment of the 1997 rule.

More Questions Remain

The EPA then moved to finalize an even stricter NAAQS for ozone in October 2015, limiting it to 0.070 ppm. While the rule is mired in litigation, the Trump administration has indicated it is working to reconsider the rule or some part of it. In November, the agency concluded that 2,646 counties, out of more than 3,100 counties in the U.S. are in attainment of the 2015 ozone NAAQS.

The EPA, meanwhile, has yet to finalize a rule proposed in December 2016 that sets out requirements for implementing the 2015 ozone NAAQS, but options set out in the proposed rule echo those vacated by the D.C. Circuit on Friday for implementation of the 2008 NAAQS.

The rule, for example, proposes to revoke the 2008 ozone NAAQS and "where applicable," provide anti-backsliding requirements to help smooth the transition between the two standards for nonattainment areas.

An EPA spokesperson told POWER on February 22 that the agency is still reviewing the federal court's decision. The EPA also intends to provide "timely" implementation rules to states for 2015 NAAQS compliance. A final implementation rule could be issued around the time nonattainment designations are effective in spring 2018.

-Sonal Patel is a POWER associate editor (@sonalcpatel, @POWERmagazine)

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