Ozone PM2.5 Carbon Monoxide Nitrogen Dioxide Sulfur Dioxide Lead
The six pollutants listed below are considered "criteria" pollutants
and have National Ambient Air Quality
Standards (NAAQS) set by the EPA Office of Air Quality Planning and
||A colorless gas that is a major constituent of smog. Ozone is found both at high altitude and ground level. High altitude ozone is beneficial because it shields the earth from the sun's ultraviolet radiation. Ground level ozone is harmful because it reacts with the mucus membranes of the respiratory
system and causes inflammation.
||Forms in the air from other pollutants: volatile organic
compounds (VOCs) and nitrogen oxides (NO and NO2) in the presence of ultraviolet (UV) radiation. Ozone does not come directly
from any source. The VOCs that form ozone come from
vehicle and industrial exhaust as well as evaporation of gasoline,
solvents and paints, and many other sources.
||Irritates the lungs and breathing passages, causing
coughing and pain in the chest and throat. Increases susceptibility
to respiratory infections and reduces the ability to exercise. Effects
are more severe in children, the elderly and people with asthma and other respiratory ailments.
Long-term exposure may lead to scarring of lung tissue and reduced lung efficiency.
||Solid matter or liquid droplets with an aerodynamic diameter
of 2.5 microns or less.
||Diesel cars, trucks and buses; power plants;
and many other sources.
|| Aggravates existing heart and lung diseases, changes
the body's defenses against inhaled materials and damages lung
tissue. Lung impairment can persist for 2-3 weeks after
exposure to high levels of particulate matter. Chemicals in and on
particulates can also be toxic. Very fine particulates can be inhaled
deeply into the lungs. When PM2.5 reaches unhealthy
levels, people with respiratory or heart disease, the elderly and
children are most at risk. Particulate matter also damages paint, soils clothing and furniture,
and reduces visibility.
||An odorless, colorless gas resulting from incomplete
combustion of fossil fuel burning.
||Product of the incomplete burning of carbon in fuels from automobiles,
buses, trucks, small engines, boilers and
some industrial processes. High concentrations can be found in confined
spaces such as parking garages, poorly ventilated tunnels, or traffic
intersections, especially during peak hours.
|| Weakens the heart's contractions and lowers the amount
of oxygen carried by the blood. Reduces one's ability to exercise
and is dangerous for people with chronic heart disease. Causes
nausea, dizziness, headaches, visual impairment, and under high
||A yellowish brown, highly reactive gas that is the primary
ingredient in formation of ground-level ozone.
||Formed from high temperature combustion such as in power plants and
|| Irritates the nose and throat, especially in people
with asthma. Appears to increase susceptibility to respiratory infections.
Also combines with volatile organic compounds (VOCs) to form
When nitrogen dioxide reaches unhealthy levels, children and people
with respiratory disease are most at risk.
||A colorless gas, odorless at low concentrations but
pungent at very high concentrations.
||Sulfur dioxide is generated primarily by the
burning of fuels that contain sulfur. The contributors to
the release of sulfur dioxide in Connecticut are oil and coal fired power plants, industrial sources, residential heating and motor vehicles.
|| Aggravates existing lung diseases, especially bronchitis.
Constricts the breathing passages, especially in people with asthma and people doing moderate to heavy exercise. Causes wheezing, shortness
of breath, and coughing. High levels of particulates appear to worsen
the effect of sulfur dioxide, and long-term exposures to both pollutants
leads to higher rates of respiratory illness. When sulfur dioxide
reaches unhealthy levels, people with asthma are most at risk. It is also the main contributor to acid rain and
||Lead is a dull gray, odorless, tasteless heavy metal.
of lead in the atmosphere is primarily accounted for by man-made processes
such as the extraction and processing of metallic ores, the incineration
of solid waste and fuel combustion. The most important sources of lead in
humans and other animals come from ingestion of foods and beverages,
inhalation of airborne lead and the eating of non-food substances such as lead-containing paint chips.
|| Clinical lead poisoning is accompanied by symptoms of intestinal cramps, peripheral nerve paralyses, anemia, and severe fatigue.
High levels of exposure results in permanent neurological, renal, or cardiovascular damage or death.
May cause damage to the brain and other parts of the body's
nervous system. Children are most susceptible to the effects of lead.
Lead can also harm wildlife.