This glossary was provided by the Georgia Department of Natural Resources, Air Protection Branch, and edited for use in this web site.

Acid rain -- Air pollution produced when acid chemicals are incorporated into rain, snow, fog or mist. The "acid" in acid rain comes from sulfur oxides and nitrogen oxides, products of burning coal and other fuels and from certain industrial processes. The sulfur oxides and nitrogen oxides are related to two strong acids: sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, winds blow them far from their source. If the acid chemicals in the air are blown into areas where the weather is wet, the acids can fall to Earth in the rain, snow, fog, or mist. In areas where the weather is dry, the acid chemicals may become incorporated into dusts or smokes. Acid rain can damage the environment, human health, and property.

Alternative fuels -- Fuels that can replace ordinary gasoline. Alternative fuels may have particularly desirable energy efficiency and pollution reduction features. Alternative fuels include compressed natural gas, alcohols, liquefied petroleum gas (LPG), and electricity. The 1990 Clean Air Act encourages development and sale of alternative fuels.

Attainment area -- A geographic area in which levels of a criteria air pollutant meet the health-based primary standard (national ambient air quality standard, or NAAQS) for the pollutant. An area may have on acceptable level for one criteria air pollutant, but may have unacceptable levels for others. Thus, an area could be both attainment and non-attainment at the same time. Attainment areas are defined using federal pollutant limits set by EPA.

BACT -- Best available control technology. It is an emission limitation that considers the cost of energy, environment, and economics in developing a degree of emission reduction that is achievable through application of good production processes, control systems, and techniques. In no event can BACT allow emissions of a pollutant in excess of a NSPS or a NESHAPS. BACT is determined on a case-by-case basis, is applied to each pollutant regulated under the Clean Air Act (federal) and is used mostly in PSD permit work.

Carbon monoxide (CO) -- A colorless, odorless, poisonous gas, produced by incomplete burning of carbon-based fuels. including gasoline, oil, and wood. Carbon monoxide is also produced from incomplete combustion of many natural and synthetic products. 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. The body's parts need oxygen for energy, so high-level exposures to carbon monoxide can cause serious health effects. Massive exposures to CO can cause death. Symptoms of exposure to carbon monoxide can include vision problems, reduced alertness, and general reduction in mental and physical functions. Carbon monoxide exposures are especially harmful to people with heart, lung, and circulatory system diseases.

CFCs (chlorofluorocarbons) -- These chemicals and some related chemicals have been used in great quantities in industry, for refrigeration and air conditioning, and in consumer products. CFCs and their relatives, when released into the air, rise into the stratosphere, a layer of the atmosphere high above the Earth. In the stratosphere, CFCs and their relatives take part in chemical reactions which result in reduction of the stratospheric ozone layer, which protects the Earth's surface from harmful effects of radiation from the sun. The 1990 Clean Air Act includes provisions for reducing releases (emissions) and eliminating production and use of these ozone-destroying chemicals.

Clean Air Act (CAA) -- The original Clean Air Act was passed in 1963, but our national air pollution control program is actually based on the 1970 version of the law. The 1990 Clean Air Act Amendments are the most far-reaching revisions of the 1970 law. In this glossary, we refer to the 1990 amendments as the 1990 Clean Air Act.

Clean fuels -- Low-pollution fuels that can replace ordinary gasoline. These are alternative fuels, including gasohol (gasoline-alcohol mixtures), natural gas, and LPG (liquefied petroleum gas).

Combustion -- Burning. Many important pollutants, such as sulfur dioxide, nitrogen oxides, and particulates (PM-10) are combustion products, often products of the burning of fuels such as coal, oil, gas, and wood.

Compliance Advisory Panel (CAP) -- A seven member panel appointed by the governor state legislature and the Air permitting agency. The panel is composed of 4 small business owners, one permitting representative, and two people to represent the public at large. The CAP provides oversight to the Small Business Assistance Program (SBAP).

Continuous emission monitoring systems (CEMS) -- Machines which measure, on a continuous basis, pollutants released by a source. The 1990 Clean Air Act requires continuous emission monitoring systems for certain large sources.

Control technology; control measures -- Equipment, processes, or actions used to reduce air pollution. The extent of pollution reduction varies among technologies and measures. In general, control technologies and measures that do the best job of reducing pollution will be required in the areas with the worst pollution. For example, the best available control technology/best available control measures (BACT, BACM) will be required in serious non-attainment areas for particulates, a criteria air pollutant. A similar high level of pollution reduction will be achieved with maximum achievable control technology (MACT) which will be required for sources releasing hazardous air pollutants.

Criteria air pollutants -- A group of very common 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. A National Ambient Air Quality Standard exists for each criteria pollutant (particulate matter, sulfur dioxide, nitrogen dioxide, ozone, carbon dioxide, and lead).

Emission -- Release of pollutants into the air from a source. We say sources emit pollutants. Continuous emission monitoring systems (CEMS) are machines, which some large sources are required to install, to make continuous measurements of pollutant release.

Enforcement -- The legal methods used to make polluters obey the Clean Air Act. Enforcement methods include citations of polluters for violations of the law (citations are much like traffic tickets), fines, and even jail terms. EPA and the state and local governments are responsible for enforcement of the Clean Air Act, but if they don't enforce the law, members of the public can sue EPA or the states to get action.

Hazardous air pollutants (HAPs) -- Toxic chemicals that cause serious health and environmental effects. Health effects include cancer, birth defects, nervous system problems, and death due to massive accidental releases such as occurred at the pesticide plant in Bhopal, India. Hazardous air pollutants are released by sources such as chemical plants, dry cleaners, printing plants, and motor vehicles (cars, trucks, buses, etc.)

Inspection and maintenance program (I/M program) -- Auto inspection programs are required for some polluted areas. These periodic inspections, usually done once a year or once every two years, check whether a car is being maintained to keep pollution down and whether emission control systems are working properly. Vehicles which do not pass inspection must be repaired. Under the 1990 Clean Air Act, some especially polluted areas will have to have enhanced inspection and maintenance programs, using special machines that can check for such things as how much pollution a car produces during actual driving conditions.

Interstate air pollution -- In many areas, two or more states share the same air. We say these states are in the same air basin defined by geography and wind patterns. Often, air pollution moves out of the state in which it is produced into another state. Some pollutants, such as the power plant combustion products that cause acid rain, may travel over several states before affecting health, the environment, and property. The 1990 Clean Air Act includes many provisions, such as interstate compacts, to help states work together to protect the air they share. Reducing interstate air pollution is very important since many Americans live and work in areas where more than one state is part of a single metropolitan area.

LAER -- Lowest achievable emission rate. Considered to be the lowest rate of emissions from a source category which is contained in the State Implementation Plan, or which is achieve in practice by such category of sources. This term is most often associated with a nonattainment area.

Major source -- Under the PSD regulations it is a facility, belonging to one or more of 28 source categories, having the potential to emit 100 tons per year of a pollutant regulated under the federal Clean Air Act (CAA). For categories other than the 28 sources, the potential emission level can not exceed 250 tons per year.

A major source for the purpose of Title V in the CAA is a stationary source that has the potential to emit 100 tons per year a pollutant regulated under the CAA and/or a source that has the potential to emit 10 tons per year for a single hazardous air pollutant or 25 tons per year of a combination of all hazardous air pollutants.

Material safety data sheets (MSDSs) -- Product safety information sheets prepared by manufacturers and marketers of products containing toxic chemicals. These sheets can be obtained by requesting them from the manufacturer or marketer. Some stores, such as hardware stores, may have material safety data sheets on hand for products they sell.

Mobile sources -- Motor vehicles and other moving objects that release pollution; mobile sources include cars, trucks, buses, planes, trains, motorcycles and gasoline-powered lawn mowers. Mobile sources are divided into two groups: road vehicles, which includes cars, trucks, and buses, and non-road vehicles, which includes trains, planes, and lawn mowers.

Monitoring (monitor) -- Measurement of air pollution is referred to as monitoring. EPA, state, and local agencies measure the types and amounts of pollutants in community air. The 1990 Clean Air Act requires states to monitor community air in polluted areas to determine if the areas are being cleaned up according to schedules set by law.

NAAQS -- National ambient air quality standards. Ambient standards developed by EPA that must be attained and maintained to protect public health. "Secondary" NAAQS are necessary to protect the public welfare. NAAQS exist for particular matter, sulfur dioxide, nitrogen dioxide, ozone, carbon dioxide, and lead.

Nitrogen oxides (NOx) -- A criteria air pollutant. Nitrogen oxides are produced from burning fuels, including gasoline and coal. Nitrogen oxides are smog formers, which react with volatile organic compounds to form smog. Nitrogen oxides are also major components of acid rain.

Non-attainment area -- A geographic area in which a criteria air pollutant level is higher than allowed by the federal standards. A single geographic area may have an acceptable level for one criteria air pollutant, but have unacceptable levels of one or more other criteria air pollutants. Thus, an area can be both an attainment and non-attainment area at the same time. Sixty percent of Americans are estimated to live in non-attainment areas.

NSR -- New source review. NSR typically means any new source locating in a, e.g., ozone nonattainment area that will emit volatile organic compounds (VOCs) and/or oxide of nitrogen (NO) in certain amounts. These sources must: undergo a new source review that provides for offsetting emissions for any increases in the emissions of these two pollutants; use the lowest achievable emissions technology to control emissions; apply for a construction permit; and meet other state requirements before the new emission from the source can be permitted. Existing sources, located in the ozone nonattainment area, that emit these two pollutants and plan to change their operational methods that will cause an increase in the emissions of these two pollutants must apply for a modification permit and under go a review similar to a new source.

NSPS -- New source performance standards. These are federal EPA emission standards for certain air pollutants that are emitted from new, modified, or reconstructed stationary emission sources which reflect the use of best available control technology

NESHAPS -- National emission standards for hazardous air pollutants.

Offset -- A method used in the 1990 Clean Air Act to give companies, which own or operate large (major) sources in non-attainment areas, flexibility in meeting overall pollution reduction requirements when changing production processes. If the owner or operator of the source wishes to increase releases of a criteria air pollutant, an offset (reduction of a somewhat greater amount of the same pollutant) must be obtained either at the same plant or by purchasing offsets from another company.

Ozone -- A gas which is a variety of oxygen. The oxygen gas found in the air consists of two oxygen atoms stuck together; this is molecular oxygen. Ozone consists of three oxygen atoms stuck together into an ozone molecule. Ozone occurs in nature; it produces the sharp smell you notice near a lightning strike. High concentrations of ozone gas are found in a layer of the atmosphere -- the stratosphere -high above the Earth. Stratospheric ozone shields the Earth against harmful rays from the sun, particularly ultraviolet B. Smog's main component is ozone; this ground-level ozone is a product of reactions among chemicals produced by burning coal, gasoline and other fuels, and chemicals found in products such as solvents, paints, and hair sprays.

Particulates: particulate matter (PM-10) -- Particulate matter is a criteria air pollutant and is a finely divided particle with an aerodynamic diameter of 10 micrometers or less. Particulate matter includes dust, soot and other tiny bits of solid materials that are released into and move around in the air. Particulates are produced by many sources, including burning of diesel fuels by trucks and buses, incineration of garbage, mixing and application of fertilizers and pesticides, road construction, industrial processes such as steel making, mining operations, agricultural burning (field and slash burning), and operation of fireplaces and wood stoves. Particulate pollution can cause eye, nose, and throat irritation and other health problems.

Permit -- A document that resembles a license that is required by the Clean Air Act for big (major) sources of air pollution, such as power plants, chemical factories and, in some cases, smaller polluters. Usually permits are issued by states, but if EPA has disapproved part or all of a state permit program, EPA will issue the permits in that state. The 1990 Clean Air Act includes requirements for permit applications, including provisions for members of the public to participate in state and EPA reviews of permit applications. Permits contain information on all the regulated pollutants at a source. Permits include information on which pollutants are presently released, how much pollution the source is allowed to release, and the control measures necessary to meet pollutant release requirements. Permits are required both for the operation of plants (operating permits) and for the construction of new plants. The 1990 Clean Air Act introduced a nationwide permit system for air pollution control.

Permit fees -- Fees paid by businesses required to have a permit. Permit fees are like the fees drivers pay to register their cars. Money from permit fees helps pay for state air pollution control activities.

Pollutants (pollution) -- Unwanted chemicals or other materials found in the air. Pollutants can harm health, the environment and property. Many air pollutants occur as gases or vapors, but some are very tiny solid particles: dust, smoke, or soot.

Primary standard -- A pollution limit based on health effects. Primary standards are set for criteria air pollutants.

PSD -- Prevention of significant deterioration. This term refers to regulations that requires a major new source or an existing source making majoring modifications to be permitted by the state before construction is started if they are located in an attainment area.

RACT -- Reasonably available control technology. It is usually an emission limit set by a state air program and is the basis for emission rates used in their SIP. It usually applies to sources in attainment areas and in most cases is less stringent than the NSPS level of control.

Reformulated gasoline -- Specially refined gasoline with low levels of smog-forming volatile organic compounds (VOCs) and low levels of hazardous air pollutants. The 1990 Clean Air Act requires sale of reformulated gasoline in the nine smoggiest areas. Some reformulated gasolines were sold in several smoggy areas before passage of the 1990 Clean Air Act.

SBA -- Small Business Administration

SBAP -- Small Business Assistance Program

SBDC -- Small Business Development Center

Secondary standard -- A pollution limit based on environmental effects such as damage to property, plants, or visibility. Secondary standards are set for criteria air pollutants.

State Implementation Plan (SIP) -- A detailed description of the programs a state will use to carry out its responsibilities under the Clean Air Act. This includes such things as rules and regulations, plans to control ozone, and ambient air standards used by a state to reduce air pollution. The Clean Air Act requires that EPA approve each state implementation plan.

Smog -- A mixture of pollutants, principally ground-level ozone, produced by chemical reactions in the air involving smog-forming chemicals. A major portion of smog-formers comes from burning petroleum-based fuels such as gasoline. Other smog-formers, volatile organic compounds, are found in products such as paints and solvents. Smog can harm health, damage the environment and cause poor visibility. Major smog occurrences are often linked to heavy motor vehicle traffic, sunshine, high temperatures and calm winds, or temperature inversion (weather condition in which warm air is trapped close to the ground instead of rising).

Source -- Any place or object from which pollutants are released. A source can be a power plant, factory, dry cleaning business, gas station, or a farm. Cars, trucks, and other motor vehicles are sources. Consumer products and machines used in industry can also be sources.

Stationary source -- A place or object from which pollutants are released which stays in place. Stationary sources include power plants, gas stations, incinerators, and houses.

Sulfur dioxide -- A criteria air pollutant. Sulfur dioxide 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. Sulfur dioxide is closely related to sulfuric acid, a strong acid. Sulfur dioxide plays an important role in the production of acid rain.

Synthetic minor permit -- A permit with practically, enforceable conditions issued to a facility. These conditions limit the amount of regulated pollutant emissions so the permitted amount of actual emissions from the facility is below potential major source emission levels. These major source thresholds are usually 100 tons per year under Title V, 50 tons per year VOC/NO in the nonattainment area for ozone; 100/250 tons per year for P.D; 10 tons per year for a single hazardous air pollutant; 25 tons per year for a combination of all hazardous air pollutants; and 50 tons per year for a new source review.

Title V permit -- Is a federal operating permit program adopted and implemented by the state. The basic program elements typically specify that major sources will submit an operating application to the specified state environmental regulatory agency according to a schedule. EPA and the affected states will review the permit issuance. The pubic also has an opportunity to comment on the permit, which is renewable every five years. Minor changes to the permit can be made without opening the permit for public participation.

Ultraviolet B (UVB) -- A type of sunlight. The ozone in the stratosphere filters out ultraviolet B rays and keeps them from reaching the Earth. Ultraviolet B exposure has been associated with skin cancer, eye cataracts, and damage to the environment. Thinning of the ozone layer in the stratosphere results in increased amounts of ultraviolet B reaching the Earth.

Vapor recovery nozzles -- Special gas pump nozzles that reduce the release of gasoline vapor into the air gas is pumped into car tanks. There are several types of vapor recovery nozzles. Therefore, nozzles may not look the same at all gas stations. The 1990 Clean Air Act requires the installation of vapor recovery nozzles at gas stations in smoggy areas.

Volatile organic compounds (VOCs) -- Organic chemicals all contain the element carbon (C). Organic chemicals are the basic chemicals found in living things and in products derived from living things, such as coal, petroleum, and refined petroleum products. Many of the organic chemicals we use do not occur in nature, but were synthesized by chemists in laboratories. Volatile chemicals readily produce vapors at room temperature and normal atmospheric pressure. Vapors escape easily from volatile liquid chemicals. Volatile organic chemicals include gasoline, industrial chemicals such as benzene, solvents such as toluene and xylene, and tetrachloroethylene (perchloroethylene, the principal dry cleaning solvent). Many volatile organic chemicals, such as benzene, are also hazardous air pollutants.

Last Updated October 26, 2007