ambient air standard, the maximum tolerable concentration of any outdoor air pollutant as set by the Environmental Protection Agency (EPA) to protect public health and the environment. The EPA considers lead, the nitrogen oxides, particulate matter, sulfur dioxide, carbon monoxide, and ozone “criteria” pollutants. Research and medical evidence show a strong correlation between many diseases and toxic chemicals, but little is known about the precise effects and movement of airborne pollutants.
