The Clean Air Act of 1970 targeted the “short and long-term effects of air pollutants on public health and welfare." This revision of the federal air pollution law defined welfare to include "weather" and "climate" among other things. Those definitions have remained through subsequent revisions of the law, and they formed one of the key arguments in subsequent legal controversy over the authority of the EPA to regulate greenhouse gases. The legal question of whether the law gave the EPA the authority to regulate greenhouse gases was settled in Massachusetts v. EPA (2007), but legal questions remained about how the agency was allowed to regulate greenhouse gases.
U.S. Code, Title 42, CHAPTER 85, SUBCHAPTER III, Sec. 7602