Air Pollution Q&AWhat Is Air Pollution?
Air pollution is the contamination of air by chemicals, soot, dust and other particulates produced by a wide range of human activity - from driving and farming to industrial production and fireplaces. Air pollution can cause problems like burning eyes and nose, itchy irritated throat, and breathing problems. In case of extreme exposure, some chemicals found in polluted air can cause cancer, birth defects, brain and nerve damage, and long-term injury to the lungs and breathing passages in certain circumstances.
Air pollution also can damage the environment and property. Scientists believe trees, lakes, and animals have been harmed by air pollution. Chemical air pollutants also can damage buildings, monuments, statues, and other structures.
Air pollution also can cause haze, which reduces visibility in national parks and elsewhere, and can sometimes interfere with aviation.
What Are the Major Air Pollutants?
Carbon Dioxide (CO2) is a generally harmless, inert gas that occurs naturally in the atmosphere. People expel CO2 when they exhale. CO2is also released when carbon-containing fossil fuels such as oil, natural gas, and coal are burned in air.
Chlorofluorocarbons (CFCs) are chemicals used in great quantities in industry, for refrigeration and air conditioning, and in consumer products. CFCs, when released into the air, rise into the stratosphere (a layer of atmosphere high above the Earth).
Hazardous Air Pollutants (HAPs) are chemicals that can cause health and environmental effects. Hazardous air pollutants can be generated by such sources as chemical plants, dry cleaners, farming equipment, wood fireplaces, and motor vehicles including cars, trucks, buses, planes.
Ozone (O3) is a gas that is a variant of oxygen. Oxygen consists of two oxygen atoms; ozone has three. Ozone in the upper atmosphere, where it occurs naturally in what is known as the ozone layer, shields the Earth from the sun's dangerous ultraviolet rays. However, at ground level, it is a pollutant with potentially toxic effects that can damage human health, the environment, crops, and a wide range of natural and artificial materials. Ground-level ozone can irritate the respiratory tract, cause chest pain, persistent cough, an inability to take a deep breath, and an increased susceptibility to lung infection. Ozone also can damage trees and plants and reduce visibility.
Ground-level ozone comes from the breakdown (oxidation) of volatile organic compounds found in solvents. It is also a product of reactions between chemicals that are produced by burning coal, gasoline, other fuels, and chemicals found in paints and hair sprays. Oxidation occurs readily during hot weather.
Nitrogen Oxide (NOx) contributes to smog and acid rain. Nitrogen oxides react with volatile organic compounds to form smog. In high doses, smog can harm humans by causing breathing difficulty for asthmatics, coughs in children, and general illness of the respiratory system. Acid rain can harm vegetation and run into lakes and rivers, which changes the chemistry of the water and makes it potentially uninhabitable for all but acid-tolerant bacteria.
Particulate Matter is any type of solid in the air in the form of smoke, dust, and vapors, which can remain suspended for extended periods. Aside from reducing visibility and soiling clothing, microscopic particles in the air can be breathed into lung tissue becoming lodged and causing increased respiratory disease and lung damage. Particulates are also the main source of haze, which reduces visibility.
Particulates are produced by many sources, including burning of diesel fuels, fossil fuels, mixing and application of fertilizers and pesticides, road construction, plowing and harvesting, industrial processes such as steel making, mining, agricultural burning, and operation of wood-burning fireplaces and woodstoves.
Sulfur Dioxide (SO2) is an odorless gas at low concentrations, but can have a very strong smell at high concentrations. SO2 is a gas produced by burning coal, most notably in power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulfur dioxide. Like nitrogen oxides, SO2 is a major contributor to smog and acid rain. SO2 is closely related to sulfuric acid, a strong acid. It can harm vegetation and metals and can cause lung problems, including breathing problems and permanent damage to lungs.
Volatile Organic Compounds (VOCs) are organic chemicals. All organic compounds contain carbon, and organic chemicals are the basic chemicals found in all living things and in all products derived from living things. VOCs include gasoline, industrial chemicals such as benzene, solvents such as toluene and xylene, and perchloroethylene (principal dry cleaning solvent). VOCs are released from burning fuel, such as gasoline, wood, coal, natural gas and from solvents, paints, glues, and other products used at home or work. Many VOCs are hazardous air pollutants.
Carbon Monoxide (CO) is an odorless, colorless gas. CO is produced by the incomplete burning of carbon based fuels, including gasoline, oil, and wood. It is also produced from incomplete combustion of natural and synthetic products, such as cigarette smoke.
Source: Environmental Health Center, A Division of the National Safety Council
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