The legal precedents that form the basis of US air quality control regulations currently in effect began with the:

The Clean Air Act Amendments of 1970 are key in establishing the foundation for modern air quality control regulations in the United States. This legislation marked a significant expansion of the federal government's role in regulating air pollution and introduced important provisions that would shape air quality management.

The amendments established the National Ambient Air Quality Standards (NAAQS), which set maximum allowable concentrations for harmful pollutants, thereby providing a framework for states to develop their own implementation plans to meet these standards. Furthermore, the 1970 amendments empowered the Environmental Protection Agency (EPA) to enforce these standards and required states to monitor air quality and report on their progress.

By significantly strengthening and expanding the existing air quality laws, the Clean Air Act Amendments of 1970 laid the groundwork for subsequent air quality regulations, making it easier to hold industries accountable for emissions and ensuring a broader public health focus. This pivotal moment in environmental law set the tone for ongoing developments in air quality regulations, affirming its importance in the evolution of U.S. environmental policy.