Six Criteria Pollutants

Sulfur Dioxide (SOx): Human-derived sources

Combustion of fuels that contain sulfur, including coal, oil, gasoline

Sulfur Dioxide (SOx): Effects/Impacts

Respiratory irritant, can exacerbate asthma and other respiratory ailments. SO2 gas can harm stomataes and other plant tissue. Converts to sulfuric acid in atmosphere, which is harmful to aquatic life and some vegetation

Nitrogen Oxides (NOx): Human-derived sources

All combustion in the atmosphere, including fossil fuel combustion, wood, and other biomass burning

Nitrogen Oxides (NOx): Effects/Impacts

Respiratory irritant, increases susceptibility to respiratory infection. An ozone precursor, leads to the formation of photochemical smog. Converts to nitric acid in atmosphere, which is harmful to aquatic life and some vegetation. Also contributes to overfertilizing terrestrial and aquatic systems.

Carbon Monoxide (CO): Human-derived sources

Incomplete combustion of any kind, malfunctioning exhaust systems, and poorly ventilated cooking fires

Carbon Monoxide (CO): Effects/Impacts

Bonds to hemoglobin thereby interfering with oxygen transport in the bloodstream. Causes headaches in humans at low concentrations; can cause death with prolonged exposure at high concentrations.

Particulate Matter: Human-derived sources

Combustion of coal, oil, and diesel, and of biofuels such as manure and wood. Agriculture, road construction, and other activities that mobilize soil, soot, and dust.

Particulate Matter Impacts

Can exacerbate respiratory and cardiovascular disease and reduce lung function. May lead to premature death. Reduces visibility, and contributes to haze and smog.

Lead (Pb): Human-derived sources

Gasoline additive, oil and gasoline, coal, old paint

Lead (Pb): Effects/Impacts

Impairs central nervous system. At low concentrations, can have measurable effects on learning and ability to concentrate.

Ozone (O3): Human-derived sources

A secondary pollutant formed by the combination of sunlight, water, oxygen, VOCs, and NOx.

Ozone (O3): Effects/Impacts

Reduces lung function and exacerbates respiratory symptoms. A degrading agent to plant surfaces. Damages materials such as rubber and plastic.

Volatile Organic Compounds (VOC): Human-derived sources

Evaporation of fuels, solvents, paints; improper combustion of fuels such as gasoline

Volatile Organic Compounds (VOC): Effects/Impacts

A precursor to ozone formation

Mercury (Hg): Human-derived sources

Coal, oil, gold mining

Mercury (Hg): Effects/Impacts

Impairs central nervous system. Bioaccumulates in the food chain.

Carbon Dioxide (CO2): Human-derived sources

Combustion of fossil fuels and clearing of land

Carbon Dioxide (CO2): Effects/Impacts

Affects climate and alters ecosystems by increasing greenhouse gas concentrations