Clean Air Act
Clean Wisconsin v. Envtl. Prot. Agency, 964 F.3d 1145 (D.C. Cir.), judgment entered, 812 F. App’x 4 (D.C. Cir. 2020).
The U.S. Court of Appeals for the District of Columbia Circuit ordered the U.S. Environmental Protection Agency (EPA) to reconsider its scientific and technical record before determining that more than a dozen counties and partial counties in five states had met the 2015 National Ambient Air Quality Pollution Standard (NAAQS) for ground-level ozone. In October 2015, EPA revised the primary and secondary NAAQS for ozone to a level of 0.070 parts per million, which triggered its obligation under Clean Air Act section 107(d)(1) to redesignate all areas in the country as nonattainment, attainment, or unclassifiable with respect to the new standards. In 2018, the petitioner environmental groups filed suit in the D.C. Circuit, alleging that EPA’s 2015 ozone NAAQS nonattainment boundary designations were arbitrary and capricious with respect to certain counties and requested that the court vacate and remand the challenged designations. After determining that at least one of the petitioners had standing to challenge each designation, the court explained that the designations were arbitrary and capricious because, among other things, EPA had treated similarly situated areas differently, drew conflicting conclusions from the same data, failed to base its decisions on data in the record, and failed to explain its decisions.