ABSTRACT
The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for six criteria pollutants. Particle pollution (also known as particulate matter) is one of these. The Clean Air Act established two types of national air quality standards for particle pollution. Primary standards set limits to protect public health, including the health of sensitive populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against visibility impairment, damage to animals, crops, vegetation, and buildings. Particle pollution contains microscopic solids or liquid droplets that can enter human lungs and cause health problems. Numerous scientific studies have linked particle pollution exposure to a variety of health issues.
