EPA has set national air
quality standards for six common pollutants (also referred to as
"criteria" pollutants), most of which have a primary and secondary
standard. Primary standards are designed to protect public health,
including the health of "sensitive" populations such as asthmatics,
children, and the elderly. Secondary standards are designed to protect
public welfare, including protection against decreased visibility and
damage to animals, crops, vegetation, and buildings.
Carbon Monoxide
Carbon monoxide (CO) is a colorless, odorless, and tasteless gas which
is highly poisonous. The most common source of carbon monoxide exposure
is motor vehicle exhaust. Exposure can also come from using
gasoline-powered tools and engines indoors.
Exposure to low levels of
carbon monoxide can cause fatigue, chest pain, shortness of breath,
memory loss, skin lesions, sweating, and flu-like symptoms. In the long
term, exposure to low levels can cause heart disease and damage to the
nervous system.
Learn more about CO
Sulfur Dioxide
Sulfur dioxide (SO2) is a colorless gas with a pungent and
suffocating odor, similar to a just-struck match. Sulfur dioxide is
formed when fuel containing sulfur, such as coal and oil, is burned.
Breathing sulfur dioxide can irritate the nose, throat, and lungs, and
cause coughing and shortness of breath. Short-term exposure to sulfur
dioxide can cause stomach pain, menstrual disorders, watery eyes,
inhibition of thyroid function, loss of smell, headache, nausea,
vomiting, fever, convulsions, and dizziness.
Learn more about SO2
Particulate Matter
Particulate Matter (PM) is the term for tiny particles found in the air.
These particles can include dust, dirt, soot, smoke, and liquid
droplets. Some particulate matter is large and dark enough to be seen,
such as soot and smoke. Other particulate matter is so fine that it can
be detected only with a microscope that examines air. Particulate
matter is in emissions from cars, trucks, buses, factories, construction
sites, tilled fields, unpaved roads, stone crushing, and burning wood.
The fine particles of
particulate matter can be inhaled deeply into the lungs, where they
remain embedded for long periods of time, or can be absorbed into the
bloodstream. Prolonged exposure can cause increased respiratory disease,
decreased lung function, chronic bronchitis, and even premature death
due to respiratory problems.
Learn more about PM
Ozone
Ozone (O3) is a gas that occurs both at the earth's ground
level, and in the earth's upper atmosphere. The ozone in the atmosphere
occurs naturally and protects life on earth from the sun's harmful
ultraviolet rays. The ozone that occurs on the ground level is formed
when sunlight reacts with pollution from motor vehicles, power plants,
industrial boilers, refineries, chemical plants, and other industrial
sources. Ground-level ozone is the main ingredient of smog, a kind of
air pollution found in many U.S. cities.
You are most likely to be
exposed to ozone in the summer, when the sun and hot temperatures react
with pollution to form ozone. Repeated exposure to ozone may cause
permanent damage to the lungs, aggravate chronic lung diseases such as
emphysema and bronchitis, and reduce the immune system's ability to
fight off infections in the respiratory system.
Learn more about O3
Nitrogen Oxides
Nitrogen Oxides (NOx) are a group of gases that are composed
of nitrogen and oxygen. Nitrogen oxides are released into the air from
motor vehicle exhaust, or the burning of coal, oil, and natural gas,
especially from electric power plants. They are also released during
industrial processes such as welding, electroplating, engraving, and
dynamite blasting. Nitrogen oxides, when combined with organic
compounds, form ground-level ozone, or smog.
Nitrogen oxides are
common pollutants found in most of the air in the United States.
Exposure to nitrogen oxides can cause rapid burning and swelling of
tissues in the throat and upper respiratory tract, difficult breathing,
throat spasms, and fluid build-up in the lungs. It can interfere with
the blood's ability to carry oxygen through the body, causing headache,
fatigue, dizziness, and a blue color to the skin and lips.
Learn more about NOx
Lead
Lead (Pb) is a heavy, soft, bluish-gray metal that occurs naturally in
the rocks and soil of the earth's crust. It is also produced from
burning fossil fuels, mining, and manufacturing. Because of health
concerns, lead and lead compounds were banned from house paint in 1978.
Lead can affect almost
every organ and system in your body. It can be equally harmful if
breathed or swallowed. The part of the body most sensitive to lead
exposure is the central nervous system, especially in children, who are
more vulnerable to lead poisoning than adults. Lead exposure can lead
to irritated eyes on contact, and cause high blood pressure, headache,
irritability, reduced memory, disturbed sleep, and mood and personality
changes.
Learn more about Pb
