*****Disclaimer: This is not legal advice and is for educational purposes only. This does not create an attorney-client privilege.
The Clean Air Act (CAA) is a federal law that was passed in 1970 as comprehensive legislation regulating airborne emissions, from both stationary and mobile sources. The only US federal legislation pertaining to air quality that predates it is Air Pollution Control Act of 1955; the act provided federal funding for research on air pollution. However the CAA is the first federal law that actually aims to control it. One of the major functions of the act is to give the Environmental Protection Agency (EPA) the authority to regulate the emissions of hazardous air pollutants by setting the Ambient Air Quality Standards (NAAQS).
These NAAQS are set for each state, taking into consideration their climate, industries and other conditions. These standards were designed and set by 1975, and were a major advancement for public health. The EPA also began to act as the axiom for coordinating the many and varied state implementation plans. The EPA assists these states in designing a plan to help them reach the EPA-set standards, while tailoring the plans to work with the industries and economy of the given state.
Though the act aimed to improve air quality, it approached it in such a way to preserve industry while putting the pressure on them to clean up their practices. The act also allowed for enforcement proceedings in regions subject to interstate transfer of air pollutants and called for the federal government to conduct more extensive monitoring studies of ambient air than ever before.
Many states failed to meet the deadline of 1975 to meet their standards. In 1977 and 1990 the act was amended to assign new goals for the date of fulfillment. As the act has been amended, it has become more comprehensive. Originally the CAA was a risk-based program that was only developed for a few standards. The major pollutants covered under the original NAAQS include carbon monoxide, sulfur dioxide, nitrogen dioxide, particulate matter (PM 2.5 and PM 10), hydrocarbons and photochemical oxidants.
The current amendments to the CAA require that the emission standards be set such that they require the maximum degree of reduction to toxic or hazardous airborne emissions. These standards are known as MACT, for the maximum achievable control technology. Even with these standards, the EPA is required to review them in order to evaluate whether any residual risk exists for the given source category and revise the standards accordingly. The plan is thus designed to evolve and be fine tuned as more research and public health data guides it.
The CAA is a testament to how effective programs guided by science and research are at improving the conditions of the environment and public health. The act is responsible for a number of successes. It phased out chlorofluorocarbons and other chemicals responsible for the hole in the ozone. It reduced the man pollutants responsible for acid rain, which are sulfur and nitrogen dioxides, by 71% and 46% and depleted ground level ozone by 25%, and reduced lead air pollution from leaded gas by 92%, all between 1980 to now. It has also reduced mercury emissions by 45% since 1990. Many people act resistant to environmental regulations, saying the curtail business; but the reality is the savings in public health costs are much greater.