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AirQ Glossary of Terms

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Abatement – the reduction in degree or intensity, or elimination, of pollution

Acid Deposition – a term for the conversion of sulfur oxide and nitrogen oxide emissions into acidic compounds which precipitate in rain, snow, fog, or dry particles

Acute – occurring over a short period of time; used to describe brief exposures and effects which appear promptly after exposure

Adverse Health Effects – health effects from exposure to air contaminants that may range from relatively mild temporary conditions, such as minor eye or throat irritation, shortness of breath, or headaches, to permanent and serious conditions such as birth defects, cancer, or damage to lungs, nerves, liver, heart, or other organs

Aerosol – particle of solid or liquid matter that can remain suspended in the air because of its small size (generally under one micron)

Afterburner – an air pollution abatement device that removes undesirable organic gases through incineration

Air – so–called "pure" air is a mixture of gases containing about 78 percent nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon, and other inert gases; and varying amounts of water vapor

Air Basins – areas defined by geographical or administrative boundaries; used for air pollution control programs

Air Monitoring – sampling for and measuring of pollutants present in the atmosphere

Air Pollution – the presence of polluting gases and suspended particles in the atmosphere in excess of air quality standards

Air Quality Criteria – the varying amounts of pollution and lengths of exposure at which specific adverse effects to health and comfort take place

Air Quality Index (AQI) – color–coded tool that shows air pollution levels.

Air Quality Management District (AQMD) – local agency charged with controlling air pollution and attaining air quality standards

Air Quality Plan (AQP) – a plan developed to attain and maintain an air quality standard

Air Quality Standard (AQS) – the prescribed level of a pollutant in the outside air that should not be exceeded during a specific time period to protect public health. Established by both federal and state governments

Airshed – a term denoting a geographical area of which, because of topography, meteorology, and climate, shares the same air (see Air Basins)

Ambient Air – outside air; any portion of the atmosphere not confined by walls and a roof

Aromatic – a hydrocarbon that consists of one or more benzenoid rings (i. e., benzene)

Asthma – a medical condition characterized by abnormal restriction of breathing, especially in response to allergens or air contaminants

Attainment – a designation used when an area meets an air quality standard

Attrition Fire – A fire whose fuel is comprised of dead or prunned tree or bush branches, limbs and cuttings.



Baghouse – an air pollution abatement device that traps particulates (dust) by forcing gas streams through large permeable bags usually made of glass fibers

Best Available Control Technology (BACT) – an emission limitation based on using the most up–to–date methods, systems, techniques, and production processes available to achieve the greatest feasible emission reductions. These are the most stringent requirements for new or modified sources and are determined on a case–by–case basis as part of New Source Review

Best Available Retrofit Control Technology (BARCT) – an emission limitation based on the maximum degree of reduction achievable for existing sources taking into account environmental, energy, and economic impact

Bi–fuel – a vehicle that has the ability to operate on gasoline or diesel as their primary fuel.

Biodiesel – Biodiesel is a cleaner–burning diesel replacement fuel made from natural, renewable sources such as new and used vegetable oils and animal fats. Like petroleum diesel, biodiesel operates in compression–ignition engines. Blends of up to 20% biodiesel (mixed with petroleum diesel fuels) can be used in nearly all diesel equipment and are compatible with most storage and distribution equipment. These low level blends (20% and less) don't require any engine modifications and can provide the same payload capacity as diesel. Using biodiesel in a conventional diesel engine substantially reduces emissions

British Thermal Unit (BTU) – a unit of heat used to describe the capacity of boilers and furnaces. One BTU equals the amount of heat required to raise the temperature of one pound of water one degree Farenheit at sea level


Carbon Dioxide (CO2) – a colorless, odorless, non–poisonous gas that results from fossil fuel combustion and is a normal constituent of ambient air

Carbon Monoxide – a colorless, odorless, toxic gas produced by the incomplete combustion of carbon–containing substances. One of the major air pollutants, it is emitted in large quantities by exhaust from gasoline–powered vehicles

Carcinogen – any substance that can cause or contribute to the production of cancer

Catalytic Converter – an air pollution abatement device used primarily on motor vehicles and other sources. It removes organic contaminants by oxidizing them into carbon dioxide and water through chemical reaction. May convert nitrogen dioxide to nitrogen and oxygen or promote other similar reactions

Chlorofluorocarbons – a family of inert, nontoxic, and easily liquified chemicals used in refrigeration, air conditioning, packaging, insulation, or as solvents and aerosol propellants. Because CFCs are not destroyed in the lower atmosphere they drift into the upper atmosphere where their chlorine components destroy the ozone layer

Clean Air Act (CAA) – long standing federal legislation that is the legal basis for the national clean air programs, last amended in 1990

Coefficient of Haze (COH) – a measurement of the quantity of dust and smoke in the atmosphere in a theoretical 1000 linear feet of air. A COH of less than 1 is considered clean air and more than 3 is considered dirty air

Compressed Natural Gas (CNG) – see Natural Gas

Congestion Mitigation Air Quality (CMAQ) – began as part of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). CMAQ funds are used to pay for transportation projects that improve air quality in “non–attainment” and “maintenance” areas — those areas where the EPA considers air quality to be poor, or where there have been air quality problems in the past. The national distribution of CMAQ funds is based on a formula that takes into account the population and severity of air quality status for each area.

Continuous Emission Monitor (CEM) – a type of air emission monitoring device installed to operate continuously inside of a smoke stack or other emission source

Criteria Air Pollutants – as required by the Clean Air Act, the EPA identifies and set standards to protect human health and welfare for six pollutants: ozone, carbon monoxide, particulate matter (PM10), sulfur dioxide, lead, and nitrogen oxide. The term "criteria pollutants" derives from the requirement that the EPA must describe the characteristics and potential health and welfare effects of these pollutants. EPA periodically reviews new scientific data and may propose revisions to the standards as a result

Cyclone – an air pollution abatement device that removes heavy particles from an air stream through centrifugal force



Degreaser – equipment which removes grease, dirt or unwanted materials from any part or product. Degreasers typically use solvents, as liquid baths or condensing vapors, to remove such material

Dew Point – the temperature at which droplets of water condense from air (dependent on the prevailing humidity)

Diesel Engine – a type of internal–combustion engine that uses low–volatility petroleum fuel and fuel injectors and initiates combustion using compression ignition (as opposed to spark ignition, which is used with gasoline engines.)

Diesel Emissions Reduction Act (DERA) – Law that appropriates funds to federal and state loan programs to either rebuild diesel–powered vehicle engines to more stringent emission standards or install emission reduction systems, notify affected parties, and share the technological information with countries that have poor air quality standards.

Dual–fuel – Engines that operate on a combination of natural gas and diesel fuel


Electrostatic Precipitator – an air pollution abatement device that removes particulate matter from a gas stream by imparting an electrical charge to the particles for mechanical collection on an electrode

Emission Factor – the relationship between the amount of pollution produced and the amount of raw material processed or burned. For example, the emission factor for oxides of nitrogen from fuel oil combustion in an industrial boiler would be the number of pounds of oxides of nitrogen emitted per 1000 gallons of fuel oil burned. By using the emission factor of a pollutant and specific data regarding quantities of material used by a given source, it is possible to compute emissions for the source. This approach is used in preparing an emissions inventory

Emission lnventory – a list of air pollutants emitted into a community's atmosphere, in amounts (commonly tons) per day or year, by type of source

Emission Standard – the maximum amount of pollution that is permitted to be discharged from a polluting source – for example, the number of pounds of dust that may be emitted per hour from an industrial process

Emulsified diesel – This is diesel that is mixed with a small percentage of water and an agent that keeps the water and diesel mixed. By adding the water to the diesel a smaller amount emissions are created when the fuel is burned

Environmental Protection Agencyan agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress

Equivalent Opacity – the application of the Ringelmann system to the evaluation of the density of other than black smoke (see Ringelmann)

Ethanol – ethyl alcohol, a volatile alcohol containing two carbons (CH3CH2OH). For fuel use, it would be produced by fermentation of corn or other plant products away

Exceedance – a measured level of an air pollutant higher than the national or state ambient air quality standard



Federal Highway Administration (FHWA) – Agency within the Department of Transportation that supports State and local governments in the design, construction, and maintenance of the Nation’s highway system.

Federal Transit Administration – an agency within the United States Department of Transportation (DOT) that provides financial and technical assistance to local public transit systems.

Flexible Fuel Vehicle – vehicles that can use either alcohol fuels (methanol or ethanol) or a combination of alcohol fuel and unleaded gasoline

Fluorocarbon – an organic compound that contains fluorine. Some of these compounds may affect health but they are non–reactive and therefore not smog forming

Fossil Fuels – coal, oil, and natural gas; so–called because they are the remains of ancient plant and animal life

Fume – solid particles under 1 micron in diameter, formed as vapors condense or as chemical reactions take place

Furnace – a combustion chamber; an enclosed structure in which fuel is burned to heat air or material


Greenhouse Effect – the warming of the earth's atmosphere caused by a buildup of carbon dioxide and other trace gases. This buildup allows light from the sun's rays to heat the earth but prevents a counterbalancing loss of heat

Ground Level Monitor (GLM) – a type of air pollution monitoring device located around major industrial facilities to measure ambient levels of certain pollutants

Ground–Level Ozone

(GLO) – see Ozone


Halogen – a family of chemical elements that includes fluorine, chlorine, bromine, and iodine

Halogenated Organic Compounds – organic compounds containing one or more atoms of a halogen. These compounds tend to be stable and non–reactive, and therefore have low smog–producing potential

Health Risk – the probability that exposure to a given set of toxic air contaminants will result in an adverse health effect. The health risk is affected by several factors: the amount and toxicity of emissions; the weather; how far sources are from people; the distance between sources; and the age, health and lifestyle of the people living and working at the receptor location. The term "risk" usually refers to the increased chance of contracting cancer as a result of an exposure and is expressed as a probability, e.g., chances–in–a–million

Health Risk Assessment – a document that identifies the risks and quantities of possible adverse health effects that may result from exposure to emissions of toxic air contaminants. A health risk assessment cannot predict specific health effects; it only describes the increased possibility of adverse health effects based on the best scientific information available

Hydrocarbon – any of a vast number of compounds containing carbon and hydrogen in various combinations; found especially in fossil fuels. Some of the hydrocarbon compounds are major air pollutants; they may be active participants in the photochemical process or affect health

Hydrogen Sulfide (H2S) – a gas characterized by a "rotten egg" smell that is often produced by and found in the vicinity of oil refineries, chemical plants and sewage treatment plants



Incineration – the burning of household or industrial waste in a combustion chamber

Inert Gas – a gas such as helium, neon, or argon that does not react with other substances under ordinary conditions

Inorganic Gaseous Pollutant – a gaseous pollutant that is not an organic compound. Examples are: sulfur dioxide, hydrogen sulfide and nitrogen oxides

Internal Combustion Engine (ICE) – an engine in which both the heat energy and the ensuing mechanical energy are produced inside the engine

Inversion – the phenomenon of a layer of warm air pressing down on cooler air below it. Inversions are a special problem because they prevent the natural dispersion and dilution of air contaminants



Kansas Department of Health and Environment (KDHE) – Assures public healthand promotes>environmental quality in the state of Kansas. Bureau of Air is responsible for permitting, emissions inventory, monitoring and planning, compliance and enforcement, and outreach and education.

Kansas Department of Transportation (KDOT) – Kansas state transportation department.


LAER (lowest achievable emission rate) – under the Clean Air Act, the rate of emissions that reflects (a) the most stringent emissions limitation in the state implementation plan identified for a source unless the owner or operator demonstrates such limitations are not achievable or (b) the most stringent emissions limitation achieved in practice, whichever is more stringent

Liquified Natural Gas (LNG) – see Natural Gas


Major Source – a source that emits or has the potential to emit more than 100 tons of any pollutant regulated under the federal Clean Air Act, more than 10 tons of any hazardous air pollutants or 25 tons of all hazardous air pollutants

Maximum Achievable Control Technology (MACT) – EPA standards mandated by the 1990 amendments to the federal Clean Air Act for the control of toxic emissions from various industries. Industries range from dry cleaners to petroleum refineries

Methanol – a single carbon alcohol, generally produced from natural gas (methane)

Metropolitan Planning Organization – federally–mandated and federally–funded transportation policy–making organization, of which MARC is one.

Micro – a prefix meaning 1/1,000,000. Abbreviated by the Greek letter µ

Micron – a unit of length equal to one thousandth of a millimeter, or about 1/25,000 of an inch

Milli – a prefix meaning 1/1,000

Missouri Department of Natural Resources (MDNR) – Missouri Department of natural resources, environmental assistance, air, land and water quality.

Missouri Department of Transportation (MoDOT) – Missouri state transportation department

Missouri Gas Energy (MGE) – Kansas City, Mo natural gas provider

Mist – liquid particles up to 100 microns in diameter

Mixing Depth – the expanse in which air rises from the earth and mixes with the air above it until it meets air of equal or warmer temperature

Mobile Source – a moving source of air pollution; includes cars, trucks, motorcycles, and airplanes



National Ambient Air Quality Standards (NAAQS) – health–based pollutant concentration limits established by EPA that apply to outside air (see Criteria Pollutants)

National Emissions Standards for Hazardous Air Pollutants (NESHAPS) – emissions standards set by EPA for air pollutants not covered by NAAQS that may cause an increase in deaths or in serious, irreversible, or incapacitating illness; includes. toxic emissions such as benzene

Natural Gas – Natural gas is a mixture of hydrocarbons (mainly methane (CH4)) and is produced either from gas wells or in conjunction with crude oil production. Because of the gaseous nature of this fuel, it must be stored onboard a vehicle in either a compressed gaseous state (CNG) or in a liquefied state (LNG)

New Source Performance Standards (NSPS) – pollutant emission limits for newly constructed sources

New Source Review (NSR) – a permitting procedure for new or modified stationary sources. NSR applies if the emissions from the new source are above a trigger level

Nitric Oxide (NO) – precursor of ozone, NO2, and nitrate; usually emitted from combustion processes. Converted to nitrogen dioxide (NO2) in the atmosphere, it then becomes involved in the photochemical process and/or particulate formation

Nitrogen Oxides (NOx, frequently pronounced “nox”) – gases formed in great part from atmospheric nitrogen and oxygen when combustion takes place under conditions of high temperature and high pressure; considered a major air pollutant and precursor of ozone

Nonattainment Area – defined geographic area that does not meet one or more of the federal air quality standards for the criteria pollutants


Open Burning – the uncontrolled burning of waste materials in the open, in outdoor incinerators, or in an open dump, either intentionally or accidentally.

Organic Compounds – a large group of chemical compounds that contain carbon. All living organisms are made up of organic compounds. Some types of organic gases, including olefins, substituted aromatics and aldehydes, are highly reactive –– i.e., have high ozone–producing potential.

Oxidant – an air pollutant containing oxygen that can react chemically with other substances. Ozone, and nitrogen compounds are examples of oxidants

Ozone (O3) – a pungent, colorless, toxic gas composed of three oxygen atoms. It is not usually emitted directly into the air, but at ground–level is created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.

Ground–level ozone (GLO) is considered "bad." Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents as well as natural sources emit NOx and VOC that help form ozone. Ground–level ozone is the primary constituent of smog. Sunlight and hot weather cause ground–level ozone to form in harmful concentrations in the air. As a result, it is known as a summertime air pollutant.

"Good" ozone occurs naturally in the stratosphere approximately 10 to 30 miles above the earth's surface and forms a layer that protects life on earth from the sun's harmful rays.

Ozone Depletion – destruction of the stratospheric ozone layer, which shields the earth from ultraviolet radiation. This destruction is caused by the breakdown of certain chlorine and/or bromine–containing compounds (chlorofluorocarbons or halons) that catalytically destroy ozone molecules in the stratosphere



Particulate – a particle of solid or liquid matter; soot, dust, aerosols, fumes and mists

Parts Per Million (PPM) – the number of parts of a given pollutant in a million parts of air

Photochemical Process – the process by which sunlight acts upon various compounds, causing a chemical reaction to occur

Photochemical Smog – produced when hydrocarbons and oxides of nitrogen combine in the presence of sunlight to form ozone

Plume – a visible or measurable discharge of a contaminant from a given point of origin that can be measured according to the Ringelmann scale

PM10 (Particulate Matter less than 10 microns) – tiny solid or liquid particles of soot, dust, smoke, fumes, and aerosols. The size of the particles (10 microns or smaller, about 0.0004 inches or less) allows them to easily enter the air sacs in the lungs where they may be deposited, resulting in adverse health effects. PM10 also causes visibility reduction and is a criteria air pollutant

PM2.5 (Particulate Matter less than 2.5 microns) – tiny solid or liquid particules, generally soot and aerosols. The size of the particles (2.5 microns or smaller, about 0.0001 inches or less) allows them to easily enter the air sacs deep in the lungs where they may cause adverse health effects; PM2.5 also causes visibility reduction

Pollutant Standards Index (PSI) – a system developed by the federal government for reporting air pollution concentrations to the public as numerical values between 0 and 500

Precipitators – any number of devices using mechanical, electrical, or chemical means to collect particulates. Used to measure, analyze, or control particulates

Precursor – compounds that change chemically or physically after being emitted into the air and eventually produce air pollutants. For example, organic compounds are precursors for ozone

Prevention of Significant Deterioration (PSD) – an EPA program in which state and/or federal permits are required to restrict emissions in areas that meet federal standards for criteria pollutants



Reactive Organic Gases (ROG) – classes of organic compounds, especially olefins, substituted aromatics and aldehydes, that react more rapidly in the atmosphere to form photochemical smog or ozone

Reasonable Further Progress (RFP) – specified rate of progress towards meeting an air quality standard, as set forth in law or in a plan

Reasonably Available Control Technology (RACT) – air pollution abatement equipment that is both technologically feasible and cost effective

Ringelmann Chart – actually a series of charts, numbered 0 to 5, that simulate various smoke densities, by presenting different percentages of black. A Ringelmann No. 1 is equivalent to 20 percent black; a Ringelmann No. 5 is 100 percent black. They are used for measuring the opacity or equivalent obscuration of smoke arising from stacks and other sources by matching the actual effluent with the various numbers, or densities, indicated by the charts



Saturated Hydrocarbon – an organic compound consisting of only carbon and hydrogen atoms with no double or triple bonds. Examples are ethane, methane and propane. They are relatively unreactive, (i.e., do not form photochemical smog as rapidity as other organics)

Scrubber – a device that uses a high energy liquid spray to remove aerosol and gaseous pollutants from an air stream. The gases are removed either by absorption or chemical reaction

Smog – a term used to describe many air pollution problems. Smog is a contraction of smoke and fog; it describes the irritating stagnant haze resulting from the sun's effect on pollutants in the air. Also known as ground–level ozone.

Soot – very fine carbon particles that appear black when visible

State Implementation Plan (SIP) – EPA–approved state plans for attaining and maintaining national ambient air quality standards

Stationary Source – a fixed, non–mobile producer of pollution, usually at industrial or commercial facilities

Storage Tank – any stationary container, reservoir, or tank used for the storage of liquids. District regulations usually only apply to the storage of organic liquids

Stratosphere – the portion of the atmosphere that is 10 to 25 miles above the earth's surface

Sulfur Oxides (SOx) – pungent, colorless gases formed primarily by the combustion of sulfur–containing fossil fuels, especially coal and oil. Considered major air pollutants, sulfur oxides may impact human health and damage vegetation


Title III – a section of the 1990 amendments to the federal Clean Air Act that deals with the control of toxic air emissions

Title V – a section of the 1990 modifications to the federal Clean Air Act that requires a federally enforceable operating permit for major sources of air pollution

Topography – the configuration of a surface, especially the earth's surface, including its relief and the position of its natural and man–made features

Total Organic Gases (TOG) – gaseous organic compounds, including reactive organic gases and relatively unreactive organic gases such as methane

Total Suspended Particulates (TSP) – particles of solid or liquid matter – such as soot, dust, aerosols, fumes and mist – up to approximately 30 microns in size

Toxic Air Pollutants – air pollutants that may cause or contribute to an increase in mortality or in serious illness or which may pose a present or potential hazard to human health

Toxic Best Available Control Technology(TBACT) – similar to BACT standards except applies to sources of toxic emissions. In many cases, it is the same as BACT. The standards are based on using the most up–to–date methods, systems, techniques, and production processes available to achieve the greatest feasible emission reductions. These are the most stringent requirements for new or modified sources and are determined on a case–by–case basis

Transportation Control Measures (TCMs) – strategies to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling or traffic congestion for the purpose of reducing motor vehicle emissions

Troposphere – the layer of the atmosphere nearest the earth's surface. The troposphere extends outward about 5 miles at the poles and 10 miles at the equator




Variance – permission granted for a limited time under stated conditions for a person or company to operate outside the limits prescribed in a regulation

Volatile Organic Compound (VOC) – an organic compound that evaporates readily at atmospheric temperatures. A major precursor of ozone


Woodburning Pollution – air pollution caused by emissions of particulate matter, carbon monoxide, and odorous and toxic substances from woodburning stoves and fireplaces