Criteria pollutant that has been reduced the MOST by actions taken after the Clean Air Act was passed. Removing this from gasoline had the biggest impact.

Sizes of this air pollutant of 2.5 micrometers or smaller, is more dangerous, leading to severe respiratory problems and heart disease.

Sources of this air pollutant include construction sites, forest fires, fields and smoke stacks.

These devices are used to remove Sulfur dioxide from smoke stacks.

These devices are used to help reduce particulate matter from smoke stacks.

Secondary pollutant created after nitrogen oxides are emitted into the atmosphere and interact with sunlight and other chemicals. Only secondary criteria air pollutant.

Air pollutant that comes from the combustion of primarily coal in factories and power plants. Major contributor to acid precipitation.

Air pollutant that is emitted from the combustion of fossil fuels mostly from automobiles and other transportation. Precursor to tropospheric ozone formation.

Catalytic converters are used to reduce these specific gases from the exhaust of vehicles.