During oral arguments before the U.S. Court of Appeals for the District of Columbia Circuit September 12, the Sierra Club asked the court to vacate the Environmental Protection Agency’s determination that it had satisfied Clean Air Act requirements to reduce emissions of certain air toxics. The Sierra Club contends that despite publishing a determination to that end, the agency has not actually satisfied the requirements to set standards to reduce polychlorinated biphenyls, polycyclic organic matter, and hexachlorobenzene.