In 2011, the Environmental Protection Agency (“EPA”) determined that the Cincinnati-Hamilton metropolitan area in Ohio had attained national air quality standards (NAAQS) for particulate matter (PM2.5), in part based on regional cap-and trade programs. EPA redesignated the area to “attainment” status. The Sierra Club appealed the redesignation because Ohio, Indiana, and Kentucky, the three States that administer the Clean Air Act programs, had never implemented “reasonably available control measures,” (RACT/RACM) in the nonattainment area. On July 14, 2015, the U.S. Court of Appeals for the Sixth Circuit, after first finding that the Sierra Club had standing to appeal, vacated EPA’s 2011 redesignation of Ohio and Indiana’s portion of the Cincinnati-Hamilton PM2.5 nonattainment area, based on the absence of RACT/RACM from those states’ approved nonattainment SIPs for the area. (Sierra Club v. EPA, 78 F.3d 299 (6th Cir. 2015).) 

In vacating the designation, the court stated that, “[i]f an area is designated as nonattainment, the State or States containing that area must revise their SIPs to meet additional requirements located in Part D of Subchapter 1, Chapter 85 of Title 42. See, e.g., id. §7502. One such requirement, which we will refer to as “RACM” or “RACT,” is that the state SIP “provide for the implementation of all reasonably available control measures [“RACM”] as expeditiously as practicable (including such reductions in emissions from existing sources in the area as may be obtained through the adoption, at a minimum, of reasonably available control technology [“RACT”]) and shall provide for attainment of the national primary ambient air quality standards.” The court summarized its conclusion saying “a State seeking redesignation ‘shall provide for the implementation’ of RACM/RACT, even if those measures are not strictly necessary to demonstrate attainment with the PM2.5 NAAQS.”

The State of Ohio appealed the 6^th Circuit decision, filing for a Writ of Certiorari in the U.S. Supreme Court. On March 28, 2016, the U.S. Supreme Court denied Ohio’s petition to review the Sixth Circuit’s decision (U.S., No. 15-684, cert. denied 3/28/16.) In its petition to the Supreme Court, Ohio sought a ruling on whether the Clean Air Act language on the use of RACT/RACM in nonattainment areas requires states to impose those measures even if they are not necessary to meet the NAAQS. The Sixth Circuit had ruled that the CAA, at §107(d)(3)(E)(ii), “unambiguously requires” nonattainment SIPs to include RACT/RACM as a prerequisite to the redesignation process. The Sixth Circuit had vacated EPA’s redesignation of parts of the Cincinnati-Hamilton nonattainment area in Ohio and Indiana, which had demonstrated attainment through the use of regional cap-and-trade programs that reduced emissions, but had never implemented RACT/RACM.

The Supreme Court’s denial of certiorari leaves the decision in place in the Sixth Circuit jurisdiction only.