National ambient air quality standards (NAAQS), §109

The D.C. Circuit vacated three provisions of EPA's 2018 rule implementing NAAQS for ozone. Environmental groups challenged four provisions of the rule: the interprecursor trading program, a…

The Fifth Circuit denied petitions to review EPA's 2018 redesignation of Bexar County, Texas, from attainment to nonattainment and designation of three neighboring counties as attainment/…

The Third Circuit granted a petition to review EPA's approval of Pennsylvania's proposed NAAQS for ozone. An environmental group argued the standards wrongly claimed to reduce pollution…

The D.C. Circuit granted in part and denied in part petitions to review EPA's attainment designations for its 2015 ozone NAAQS. Environmental groups, municipal governments, and the state of…

A district court granted in part an environmental group's motion for summary judgment to compel EPA to act on its 2016 Plan for the 2008 eight-hour ozone NAAQS adopted by the San Joaquin…

A district court ordered EPA to issue federal implementation plans fully resolving interstate transport obligations under the CAA's "good neighbor" provision for the 2008 ozone…

The D.C. Circuit held that EPA unlawfully revoked the 1997 ozone NAAQS when it implemented the 2008 standard. In 2008, EPA set the ozone NAAQS at 75 parts per billion (ppb). In 2015, when…

The D.C. Circuit upheld EPA's compliance deadlines for states to meet the NAAQS for fine particulate matter (PM2.5). The court previously had ruled that the framework EPA had been applying to…

A district court ordered EPA to impose a "good neighbor” federal implementation plan (FIP) for Texas with respect to the 1997 fine particulate matter (PM2.5) NAAQS. In 2015, the D.C. Circuit…

A district court dismissed environmental groups' CAA citizen suit against EPA for failing to respond to their 2011 petition concerning ammonia gas pollution. In 2011, the groups petitioned…