Glossary of Terms
Air Pollution
The contamination of the atmosphere by waste gases, fuel exhaust, particulate matter such as smoke, and the like.
Air Quality Monitoring
Periodic or continuous surveillance or testing to measure polluntants in the air.
Ambient Air
That portion of the atmosphere, external to buildings, to which the general public has access.
Attainment Area
A region or area that meets the National Ambient Air Quality Standards (NAAQS) set by EPA.
Carbon Dioxide (CO2)
A colorless, odorless gas that consists of one atom of carbon and two atoms of oxygen. It is the product of a chemical reaction between carbon-based materials and oxygen
Carbon Monoxide (CO)
A colorless, odorless, poisonous gas, produced by incomplete burning of carbon-based fuels, including gasoline, oil and wood. For instance, cigarette smoke contains carbon monoxide. When carbon monoxide gets into the body, the carbon monoxide combines with chemicals in the blood and prevents the blood from bringing oxygen to cells, tissues and organs.
Chlorofluorocarbons (CFCs)
Any of various gaseous compounds of carbon, hydrogen, chlorine, and fluorine. These chemicals and some related chemicals have been used in great quantities in industry, for refrigeration and air conditioning, and in consumer products. When CFCs and their relatives are released into the air, they rise into the stratosphere. In the stratosphere, CFCs take part in chemical reactions which result in reduction of the stratospheric ozone layer (good ozone), the layer which protects the Earth’s surface from harmful effects of radiation from the sun
Clean Air Act
The legislation, originally enacted in 1963, revised in 1970 and 1977, and amended in 1990, which is the basis for the national air pollution control program.
Climate
The characteristic meteorological conditions, such as temperature, precipitation, and wind, that prevail in a particular area or region over a period of time.
Climatology
The science of how the Earth’s temperature and weather patterns are created and changed.
Combustion
Burning, or rapid oxidation, accompanied by a release of energy in the form of heat and light. A basic cause of air pollution.
Concentration
The amount of a substance contained in a specific quantity of another solution or a mixture.
Contaminant
Any physical, chemical, biological, or radiological substance or matter that has an adverse affect on air, water, or soil.
Convection
A meteorological term meaning a rapid upward movement of air that occurs through the strong heating of the Earth’s surface and supportive atmosphere instability. Winds and currents are mainly driven by convection in the atmosphere and in the oceans
Criteria (air) Pollutant
One of a group of air pollutants regulated by EPA on the basis of criteria (information on health and/or environmental effects of pollution). Criteria air pollutants are widely distributed all over the country.
Emissions
Pollution discharged into the atmosphere from a source such as smokestacks, vents, and other areas of commercial or industrial facilities; from residential activities; and from motor vehicle, locomotive, and aircraft exhaust.
Emission Standard
A numerical quantity that defines the allowable rate at which a contaminant may be discharged.
Extrapolation
A scientific method of applying or transferring experimental observations from a model to the real world. Extrapolation is frequently necessary because effects in the real world are usually too slow or too minute to measure.
Hydrocarbons
Chemical compounds that consist entirely of carbon and hydrogen. Hydrocarbons are a major contributor to ozone.
Hypothesis
A supposition, hunch or guess about what or why something happens. More specifically, a proposition put forth as a basis for reasoning; a supposition formulated from proved data and presented as a temporary explanation of an occurrence, as in the sciences, often to establish as basis for further research.
Lead
A heavy metal that may be hazardous to health if breathed or swallowed (for example, by a child eating soil or paint contaminated with lead). Lead occurs in the atmosphere as particulate matter originating from natural and artificial pollution sources.
Mitigation
The reduction of impacts caused by pollution. Mitigation can include preventing the pollution, cleaning up the pollution, or reducing the pollution. Mitigation can be accomplished through engineering solutions (such as air pollution “scrubbers” on power plants) or process solutions (such as recycling).
Mobile Source Emissions
The release of pollutants into the air from motor vehicles
Monitoring
Periodic or continuous surveillance or testing to collect specific types of data. Air is monitored to measure air pollution. See Air Quality Monitoring.
National Ambient Air Quality Standards (NAAQS)
Levels of pollutants that cannot be exceeded. These levels are prescribed by law or regulation for outside air.
Nitrogen Dioxide (NO2)
The result of nitric oxide combing with oxygen in the atmosphere. It is a major component of ozone.
Nitrogen Oxides (NOx)
Gases formed in great part from atmospheric nitrogen and oxygen when combustion takes place under conditions of high temperature and pressure. Nitrogen oxides include nitric oxide (NO) and nitrogen dioxide (NO2).
Nonattainment Area
A region or area that fails to meet the National Ambient Air Quality Standards (NAAQS) set by EPA.
Ozone (O3)
A principal component of smog. Ozone can be either good or bad for living things, depending upon where it is. Ground-level ozone or “bad” ozone is harmful and can cause adverse health effects, and is known to harm trees and plants. However, an ozone layer (“good” ozone) that exists naturally in the stratosphere keeps out most of the dangerous ultraviolet rays from the sun that can cause skin cancer
Particulate Matter
Very small particles, such as dust of fiber. The major source of atmospheric particulates includes combustion of coal, gasoline, and fuel oil; cement production; lime kiln operation; incineration; and agricultural burning.
Photochemical Reaction
A chemical reaction in the atmosphere that is triggered by sunlight. Ozone is a pollutant created from a photochemical reaction.
Point Source
A discrete stationary source of pollution, such as a smoke stack.
Policy
Any plan or course of action adopted by a government, business organization, or the like, designed to influence and determine decisions and actions. For example, Clean Air regulations constitute policy issued by the EPA to control air pollution.
Pollutant
Any substance introduced into the environment that adversely affects the usefulness of a resource. Air pollutants are unwanted chemicals or other materials found in the air, such as gases, vapors, dust, smoke, or soot.
Pollution
An adverse impact upon the natural environment. For example, air pollution can come from the stacks of power plants when they burn oil or coal to produce electricity or from the operation of automobiles
Prediction
A projection in advance of an event based on observation, experience, or scientific reason.
Respiration
The physical and chemical processes by which an organism supplies its cells and tissues with the oxygen needed for metabolism and relieves them of the carbon dioxide formed in energy producing reactions.
Scientific Method
An iterative process in which a hypothesis is tested through experiments and compared to observation.
Smog
A mixture of pollutants, principally ground-level ozone (“bad” ozone), produced by chemical reactions in the air. Smog can harm health, damage the environment, and cause poor visibility.
Stratospheric Ozone (Good Ozone)
Ozone located in the portion of the atmosphere that is a few miles above the Earth’s surface. Ozone at this altitude filters out harmful sun rays, including those that may cause health and environmental damage.
Sulfur Dioxide (SO2)
A colorless, irritating gas formed by the burning of sulfur-containing material. Sulfur dioxide can react with other atmospheric chemicals to form sulfuric acid.
Thermal Inversion
A layer of warm air settling over a layer of cool air that lies near the ground. This condition prevents air pollution from rising and dissipating.
Tropospheric Ozone (Bad Ozone)
Ground-level ozone (“bad” ozone), produced by chemical reactions in the air. Ozone can harm health, damage the environment, and cause poor visibility.
Volatile Organic Compounds (VOCs)
Organic compounds, such as gasoline, industrial chemicals, and solvents that participate in atmospheric photochemical reactions.
Weather
Meteorological term meaning the condition of the atmosphere at a particular time or area with respect to temperature, moisture, cloud cover, and wind velocity.