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DFE World: Design & the Global Environment
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Air Pollution

 

National Ambient Air Quality Standards

Since 1970, the Clean Air Act has provided the primary framework for protecting people and the environment from the harmful effects of air pollution by reducing the emission of "hazardous air pollutants (HAPs)." Stationary sources emit about one-half of the anthropogenic HAPs.

 

 

Health Effects

People who are exposed to HAPs at sufficient concentrations for sufficient durations may develop and increased risk of contracting forms of cancer or experiencing other serious health effects. Depending on which air pollutants an individual is exposed to, these health effects can include damage to the immune system, as well as neurological, reproductive, developmental, and respiratory problems.

 

The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health.  These standards are “harm-based” standards, meaning economic implications are not considered. Secondary standards set limits to protect public welfare.

 

The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air Quality Standards for six principal pollutants, which are called "criteria" pollutants considered harmful to public health and the environment. They are listed below. Units of measure for the standards are parts per million (ppm) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (g/m3).