Empowered by the Clean Air Act of 1970, the U.S. Environmental Protection Agency (EPA) quickly established air quality standards to protect public health and the environment. Focusing on six “criteria” air pollutants—sulfur dioxide, nitrogen dioxide, particulate matter, carbon monoxide, ozone, and lead—the resultant National Ambient Air Quality Standards became the centerpiece of air pollution regulations and required that all U.S. states, cities, and towns maintain levels of these pollutants beneath the mandated ceilings or face substantial “nonattainment” fines and penalties. Similar standards were soon adopted by a number of other countries. The impact of the Clean Air Act and the ...(100 of 175 words) Access the full article Help support true facts by becoming a member. Subscribe today!