Clean Air Act (1970)
The Clean Air Act Extension of 1970 (84 Stat. 1676, Public Law 91-604) is a United States federal law that requires the United States Environmental Protection Agency (EPA) to develop and enforce regulations to protect the general public from exposure to air pollution that are known to be hazardous to human health. This law is an amendment to the Clean Air Act (CAA) originally passed in 1963. It is sometimes called the Muskie Act because of the central role Maine Senator Edmund Muskie played in drafting the content of the bill. 
In accordance with Sections 111 and 112 of the CAA, the EPA established New Source Performance Standards (NSPS) and National Emissions Standards for Hazardous Air Pollutants (NESHAP) to protect the public.
The Clean Air Act was made federal law in 1970 and is significant in that it was the first major environmental law in the United States to include a provision for citizen suits.
Enforcement by states
In the creation of the act the federal government charges the Environmental Protection Agency with enforcing the CAA in 49 states (California is exempt). However, the EPA has allowed the individual states to elect responsibility for compliance with and regulation of the CAA within their own borders in exchange for funding. The election is not mandatory and in some cases states have chosen to not accept responsibility for enforcement of the act and force the EPA to assume those duties. In order to take over compliance with the CAA the states must write and submit a State Implementation Plan (SIP) to the EPA for approval. The SIP must meet the minimum criteria established by the EPA. The SIP becomes the state's legal guide for local enforcement of the CAA. For example, in the case of Rhode Island, the Rhode Island General Law Title 23 Chapter 23 Section 2 (RIGL 23-23-2) states that it is a state policy requirement to comply with the Federal CAA through the SIP. The state SIP delegates permitting and enforcement responsibility to the state Department of Environmental Management (RI-DEM).
- "Muskie Act". Toyota Motor Corp.