2018 is turning out to be a banner year for nationally applicable developments—both judicial and administrative—with regard to National Ambient Air Quality Standards (“NAAQS” or “Standards”) for ozone. As the year began, EPA was proceeding with implementation of the ozone NAAQS that it set in 1997 and 2008 in accordance with a rule that it had promulgated in 2015 describing requirements for State Implementation Plans (SIPs) and the transition from the 1997 NAAQS to the more stringent 2008 one. 80 Fed. Reg. 12264 (Mar. 6, 2015) (2015 SRR). The Trump administration was reviewing the prior administration’s 2015 decision further tightening the NAAQS to determine whether those more stringent NAAQS should be maintained, modified or reconsidered. To allow the Trump administration to complete that review, the DC Circuit placed in abeyance litigation challenging the 2015 Standards as either too stringent or too lenient. Murray Energy v. EPA, No. 15-1385 (D.C. Cir. Oct. 26, 2015). EPA had designated most of the country attainment/unclassifiable for the 2015 NAAQS, but had not made designations for other areas. 82 Fed. Reg. 54232 (Nov. 16, 2017).

That status continued only until February 16, when the DC Circuit vacated several key aspects of the 2015 SRR. South Coast Air Quality Mgmt. Dist. v. EPA, 882 F.3d 1138 (D.C. Cir. 2018). Among the nine provisions that the court vacated were those that ended a requirement for transportation conformity in maintenance areas for the 1997 NAAQS (i.e., areas that had been redesignated from nonattainment to attainment for that Standard) and areas designated attainment for the 2008 NAAQS that had never been redesignated attainment for the less-stringent 1997 Standard. Other vacated provisions include one that provided a “redesignation substitute” that EPA had developed because the 1997 NAAQS had been revoked, and the Agency no longer intended to consider requests for areas to be redesignated attainment for it. In addition, the court said that EPA could not waive the attainment deadlines for the 1997 NAAQS, adding them to the anti-backsliding measures required in areas that have never been redesignated to attainment for that revoked Standard. Both EPA and the South Coast Air Quality Management District have petitioned for rehearing by the panel of certain aspects of the South Coast decision. At the time of writing, the court had not acted on those petitions. In the meantime, the court’s mandate has not issued, so the decision has yet to take legal effect.

 Assuming that the court does not modify its South Coast decision, both EPA and states will have to address what that decision means for implementation of the 1997 and 2008 ozone NAAQS. The decision does not provide any obvious opportunity for areas that were once designated nonattainment to stop performing transportation conformity, even if they have since been redesignated to attainment. Nor does the decision suggest a ready route other than redesignation to attainment for ending all applicable anti-backsliding requirements for previous NAAQS, even if those NAAQS are clearly less stringent than subsequently promulgated ones.

Obtaining redesignation to attainment for many of the areas directly affected by the decision may not be as burdensome as it might initially seem, however. Apart from Denver and several areas in California, all areas currently designated nonattainment for the 1997 NAAQS and many of those designated nonattainment for the 2008 NAAQS have received Clean Data Determinations from EPA. These determination indicate that the Agency has found that air quality in these areas meets the Standard in question. Although states would be required to prepare maintenance plans for these areas before they could be redesignated to attainment, EPA’s long-standing policy is that measures to achieve attainment (including requirements for reasonable further progress, contingency measures, milestones and an attainment demonstration) are no longer applicable once an area has been found to have clean data and are not needed for redesignation of such an area to attainment. See Memorandum from John S. Seitz, Director, Office of Air Quality Planning and Standards, EPA, to Regional Air Directors (May 10, 1995) (Reasonable Further Progress, Attainment Demonstration, and Related Requirements for Ozone Nonattainment Areas Meeting the Ozone National Ambient Air Quality Standard), This interpretation should substantially reduce the burden on states when preparing a request for redesignation.

At the same time that it is grappling with the implications of the South Coast case for its implementation of the 1997 and 2008 ozone NAAQS, EPA must continue efforts to address the still-more-stringent NAAQS set in 2015. This year has also already featured several developments that affect those efforts. On March 12, 2018, in response to cases filed by several state and environmental groups, the U.S. District Court for the Northern District of California ordered EPA to promulgate designations for the 2015 NAAQS for all remaining areas except San Antonio by April 30, 2018, and to promulgate designations for the San Antonio area no later than July 17, 2018. In re ozone Designation Litigation, No. 17-cv-06900-HSG N.D. Cal. Mar. 12, 2018) (order granting summary judgment). Consistent with this order, Administrator Pruitt signed a final rule on April 30, 2018 that designates fifty-one areas nonattainment and other areas (but not around San Antonio) unclassifiable or attainment/unclassifiable. That rule has not appeared in the Federal Register. In the meantime, EPA has indicated its preliminary intent to designate all San Antonio area counties either attainment/unclassifiable or unclassifiable by its July 17 deadline.

 These nonattainment designations for the 2015 Standard have triggered yet additional activity on ozone NAAQS this year and will continue to do so. Citing these designations, on May 15, 2018, State Petitioners and State Petitioner-Intervenors in the Murray Energy case filed a motion asking the DC Circuit to lift its order placing the case in abeyance. The states express a preference that oral argument in that case, which was fully briefed before being put in abeyance, be scheduled in September 2018. EPA has until June 8, 2018 to respond to the states’ motion.

 As the State Petitioners and State Petitioner-Intervenors explain in their Murray Energy motion, nonattainment designations for the 2015 NAAQS trigger obligations for states to prepare SIPs to bring those areas into attainment. States currently lack clarity about their obligations for these SIPs. Although EPA proposed a rule in 2016 that would have addressed those obligations in some detail, 81 Fed. Reg. 81276 (Nov. 17, 2016), the Agency has yet to finalize that rule. Moreover, finalizing the rule will be complicated by (1) the change in administration since the proposal, and (2) the South Coast decision discussed above. EPA’s most recent regulatory agenda projects a May 2018 date for the final rule, but that projection seems unrealistically optimistic. Nevertheless, EPA will be under pressure to finalize at least some parts of the rule later this year. Administrator Pruitt’s recent direction that implementation regulations and guidance should be provided at the time a NAAQS is revised will only increase that pressure. See Memorandum from E. Scott Pruitt, Administrator, EPA, to Assistant Administrators (May 9, 2018) (Back-to-Basics Process for Reviewing National Ambient Air Quality Standards),

 Finally, as if all of the activities described above were not enough to keep EPA busy on ozone NAAQS issues this year, the Administrator, in the Back-to-Basics memorandum, also instructed the Agency to begin the next review of the ozone NAAQS, with the object of completing that review by October 2020. This schedule reflects a considerable acceleration compared to past NAAQS reviews. To date, EPA has not undertaken any public actions toward reviewing the 2015 NAAQS. If the Agency is to have any chance of completing such a review by the Administrator’s target date, the review must commence immediately.

In short, 2018 has already seen a great deal of judicial and administrative activity at the national level concerning the NAAQS for ozone. The pace of that activity is likely to increase further for the remainder of the year.