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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

AP-42:
A U.S. EPA document containing accepted emission factors which can be used to estimate emissions and potential to emit from common air pollutant sources. The full title is Compilation of Air Pollutant Emission factors.
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Attainment/nonattainment Areas:
Areas (usually counties within states), which have been classified as either meeting (attainment areas) or not meeting (nonattainment areas) National Ambient Air Quality Standards (NAAQS) for the six criteria pollutants. All areas of the U.S. have been classified for attainment status.
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BACT (Best available control technology):
Control technology that must be applied to new sources that exceed the prevention of significant deterioration threshold in attainment areas.
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Catalytic Oxidizer:
Thermal oxidizer that uses a catalyst bed that results in lower required temperatures for destruction of HAPs and VOCs.
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Clean Air Act:
The current Federal legislation in place for air pollution regulation, as amended in 1990.
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Co-firing:
The firing of two fuels simultaneously to reduce emissions from the higher polluting fuel. Natural gas is usually used with coal in this application.
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Criteria Pollutants:
The six criteria pollutants are 1) ozone (regulated via its precursors, volatile organic compounds [VOCs] and nitrogen oxides {NOx}); 2) sulfur dioxide (SO2); 3) particulates with a diameter of less than 10 microns (PM10); 4) nitrogen oxides (NOx); 5) carbon monoxide (CO); and 6) lead.
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External Combustion:
When referring to engines, combustion in which ignition occurs outside the chamber in which heat is converted to mechanical energy; external sources include steam/electric generating plants, industrial boilers, and commercial and domestic combustion units. Coal, fuel oil, and natural gas are the major fossil fuels used by these sources. Power generation, process heating, and space heating are some of the largest fuel combustion sources of sulfur oxides, nitrogen oxides, and particulate emissions.
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Flue Gas Recirculation:
Method of bringing flue gases back through a burner where they mix with combustion air to cool the flame to reduce NOx emissions.
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Fuel Staging:
Modifications made to conventional burners for boilers, process heaters, furnaces and ovens that delays combustion of the fuel to reduce NOx emissions.
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Hazardous Air Pollutants (HAPs):
The 190 pollutants listed in Section 112(b) of the Clean Air Act Amendments of 1990, as modified by any deletion or addition petitions.
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LAER:
Lowest Achievable Emission Rate. The most effective control technology demonstrated in practice, without regard to cost. LAER is required for new sources of criteria pollutants in nonattainment areas.
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Low NOx Burner:
General term used to describe burners that have been designed to reduced NOx emissions.
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MACT:
Maximum Achievable Control Technology. MACT standards are set by the EPA for existing and new sources of hazardous air pollutants.
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Major Source:
A facility with a facilitywide potential to emit: 1) 100 tons/yr of any federally regulated pollutant; 2) 10 tons/yr of any single HAP; or 3) 25 tons/yr of any combination of HAPs.
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National Ambient Air Quality Standards (NAAQS):
Federal ambient air standards which have been established for the six criteria pollutants. NAAQS are not enforced directly against air emission sources, but are enforced through state rules established as part of State Implementation Plans for attainment and maintenance of NAAQS.
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New Source Performance Standards (NSPS):
Federal emissions standards for new sources, primarily regarding criteria pollutants. NSPS are federally enforceable.
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New Source Review (NSR):
Federal preconstruction permitting requirements for major sources and major modifications or additions for criteria pollutants. Major source thresholds for new sources are generally 100 tons/yr in nonattainment areas and 250 tons/yr in nonattainment areas. Modification thresholds vary by pollutant. Major sources in this context are not necessarily the same as major sources for Title V permits.
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NOx:
Nitrogen oxides, formed during the combustion of fossil fuels. Usually measured as NO2.
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Prevention of Significant Deterioration (PSD):
Federal regulations that address new source requirements in attainment areas.
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Pyrolysis:
Chemical change of a substance produced by the action of heat.
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RACT:
Reasonably Available Control Technology is required on existing sources in areas that are not meeting national ambient air quality standards.
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RACT/BACT/LAER Clearinghouse:
A central database of air pollution technology information (including past RACT, BACT, and LAER decisions contained in NSR permits) to promote the sharing of information among permitting agencies and to aid in future case-by-case determinations of controls required.
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State Implementation Plan (SIP):
Collective term referring to state air rules and other control measures taken by states in order to achieve and maintain NAAQS.
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Selective Catalytic Reduction (SCR):
A post-combustion control device that mixes ammonia gas with the flue gas from a gas turbine, engine or boiler and passes the mixture across a catalytic bed for NOx reductions in excess of 80%.
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Thermal Oxidizer:
A variety of pollution control devices that burn HAPs and VOCs at relatively high temperatures.
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Three-way catalyst:
A catalyst used as a post-combustion device on engines (usually rich burn) that reduces NOx, CO and unburned hydrocarbons.
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Title I:
Portion of the Clean Air Act (as amended in 1990) that outlines the standards for air pollution prevention and control.
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Title V Permit:
A federal-level operating permit created by Title V of the Clean Air Act. These permits must be obtained for any major source.
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VOCs:
Volatile organic compounds. Many of these are also HAPs.
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