This chapter summarizes the nature, history, health effects, regulations, trends, and control of environmental air pollution. Air pollution is a combination of both anthropogenic and natural origins. During the height of the industrial revolution, the health effects of air pollution in cities became apparent. The first federal legislation involving air pollution was the Air Pollution Control Act of 1955, which provided funds for federal research on air pollution. It was followed by the Clean Air Act of 1963, which established a program within the US Public Health Service for research on air pollution monitoring and control techniques. Later, the Air Quality Act of 1967 expanded the federal government's role involving air pollution by enacting enforcement procedures concerning interstate transport of pollutants. The Clean Air Act of 1970 brought about a number of significant changes and has had two amendments. The trends in the level and the health effects of various chemical pollutants have been presented.