Criteria Air Pollutants & Their Health Effects





Most At Risk


Human Health and Welfare Effects



PM 10, PM 2.5

Particulate Matter
Airborne solid or liquid particles, smaller than 10 microns in diameter or smaller than 2.5 microns


Power plant boilers, steel mills, chemical plants, unpaved roads and parking lots, wood-burning stoves and fireplaces. Automobiles and other.
People with lung disease and/or cardiovascular disease.
 Can trigger asthma attacks and cause wheezing, coughing and respiratory irritation in individuals with sensitive airways.   May carry toxic materials deep into the respiratory system.
 Pollution control equipment and reduction of fossil fuel combustion.  Reductions in Federal particulate emissions standards.

SO 2

Sulfur Dioxode               A colorless nonflammable gas.
Power plant boilers, sulfuric acid plants, petroleum refineries, smelters, paper mills, and fuel combustion in diesel engines
Children or adults who are active outdoors.
Respiratory irritant. Bronchoconstriction or a narrowing of the airways, causing wheezing, chest tightness and shortness of breath. Long-term exposure can cause respiratory illness.
Use of low sulfur fuel, energy conservation (reduces power plant emissions), and pollution control equipment.


Carbon Monoxide           An odorless and colorless gas.


 Incomplete combustion of carbon-based fuels in motor vehicle and industrial boilers.
Those with cardiovascular disease, pregnant women, and young children.
Reduces the amount of oxygen reaching the body’s organs and tissues. Cardiovascular patients may experience chest pain or other symptoms.   CO affects mental alertness and vision, causes dizziness, and can lead to unconsciousness or death.
Transportation planning, vehicle maintenance and tune-ups, more efficient engines, use of alternative fuels, and energy conservation.

O 3

Ozone         (Smog) A colorless or bluish gas.


Formed from emissions of volatile organic compounds (VOC) and nitrogen oxides in the presence of sunlight. Fuel combustion in motor vehicles, gasoline storage and transport, solvents, paints and landfills.
Children, elderly, adults active outdoors, and people with respiratory diseases.
Inflammation and irritation of the respiratory tract.   Breathing difficulty, coughing and throat irritation.   Can affect lung function and worsen asthma attacks.
Use of low-emissions solvents and paints, evaporative controls, vehicle maintenance and tune-ups, pollution control equipment.

NO 2

Nitrogen Dioxode               A reddish-brown gas.
Fuel combustion in motor vehicles and industrial sources.
Children and those with respiratory diseases.
Respiratory irritant. Coughing, wheezing and shortness of breath may occur. Can also increase the risk of respiratory illness in children.
Exhaust gas recirculation in cars, reduction of combustion temperatures in industrial sources, energy conservation, use of alternative fuels,  and pollution control equipment.


A toxic heavy metal.
Smelters, lead-acid battery manufacturing, electric arc furnaces, incineration of garbage containing lead products, and use of leaded gasoline.
Infants and children are sensitive to low levels of lead.
Toxic and damaging to the nervous system, brain, heart, and other organs.
Phase-out of leaded gasoline, and use of pollution control equipment in industrial plants.