Minor NSR Permit Glossary: Key Terms & Definitions for Developers and Consultants

Minor NSR Permit Key Terms & Definitions

Actual Emissions: The quantity of regulated air pollutants emitted from a stationary source, as determined through continuous emissions monitoring, periodic stack testing, or other approved methods. (40 C.F.R. § 51.166(b)(21))

Air Quality Control Region (AQCR): An area designated by the EPA or a state for the purpose of air quality management and planning. (42 U.S.C. § 7407)

Ambient Air: The portion of the atmosphere, external to buildings, to which the general public has access. (40 C.F.R. § 50.1(e))

Attainment Area: A geographical area where the concentration of a criteria pollutant meets the National Ambient Air Quality Standards (NAAQS). (42 U.S.C. § 7407(d)(1)(A)(ii))

Best Available Control Technology (BACT): An emission limitation based on the maximum degree of reduction achievable for each regulated pollutant, taking into account energy, environmental, and economic impacts. (40 C.F.R. § 52.21(b)(12))

Continuous Emissions Monitoring System (CEMS): The total equipment necessary for the determination of a gas or particulate matter concentration or emission rate using pollutant analyzer measurements and a conversion equation, graph, or computer program to produce results in units of the applicable emission limitation or standard. (40 C.F.R. § 51.166(b)(43))

Criteria Pollutants: The six common air pollutants for which the EPA has established National Ambient Air Quality Standards (NAAQS): carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM10 and PM2.5), and sulfur dioxide (SO2). (40 C.F.R. Part 50)

Emission Factors: Numerical values that relate the quantity of pollutants released to the atmosphere with an activity associated with the release of that pollutant, such as the amount of pollutant emitted per unit of fuel consumed or material processed. (EPA, AP-42)

Fugitive Emissions: Emissions which could not reasonably pass through a stack, chimney, vent, or other functionally equivalent opening. (40 C.F.R. § 51.166(b)(20))

Hazardous Air Pollutants (HAPs): Air pollutants that are known or suspected to cause cancer, reproductive effects, birth defects, or other serious health effects. The Clean Air Act identifies 187 HAPs. (42 U.S.C. § 7412(b))

Lowest Achievable Emission Rate (LAER): The most stringent emission limitation derived from either the most stringent emission limitation contained in the implementation plan of any state for a similar source or the most stringent emission limitation achieved in practice by such class or category of source. (40 C.F.R. § 51.165(a)(1)(xiii))

Major Source: Any stationary source or group of stationary sources located within a contiguous area and under common control that emits, or has the potential to emit, air pollutants in amounts exceeding designated thresholds. (40 C.F.R. § 51.166(b)(1)(i))

National Ambient Air Quality Standards (NAAQS): Standards established by the EPA for criteria pollutants, defining the maximum allowable concentrations that are protective of public health and welfare. (42 U.S.C. § 7409)

New Source Performance Standards (NSPS): Nationally uniform emission standards set by the EPA for specific categories of new, modified, or reconstructed stationary sources. (42 U.S.C. § 7411)

Nonattainment Area: A geographical area where the concentration of a criteria pollutant exceeds the National Ambient Air Quality Standards (NAAQS). (42 U.S.C. § 7407(d)(1)(A)(i))

Offsets: Reductions in emissions from existing sources that are used to compensate for increases in emissions from new or modified sources in nonattainment areas. (42 U.S.C. § 7503(c))

Potential to Emit (PTE): The maximum capacity of a stationary source to emit a pollutant under its physical and operational design, considering any physical or operational limitations, including air pollution control equipment and restrictions on hours of operation or on the type or amount of material combusted, stored, or processed. (40 C.F.R. § 51.166(b)(4))

Prevention of Significant Deterioration (PSD): A permitting program designed to protect air quality in attainment areas by limiting the allowable increases in ambient concentrations of certain pollutants above baseline levels. (40 C.F.R. § 52.21)

Reasonably Available Control Technology (RACT): The lowest emission limitation that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility. (44 FR 53762)

Regulated NSR Pollutant: Pollutants for which a National Ambient Air Quality Standard has been promulgated, as well as other pollutants subject to regulation under the Clean Air Act, such as sulfuric acid mist, hydrogen sulfide, and total reduced sulfur. (40 C.F.R. § 51.166(b)(49))

Significant Emissions Rate: Thresholds for each regulated NSR pollutant above which a source is considered to have a significant net emissions increase, triggering PSD or Nonattainment NSR permitting requirements. (40 C.F.R. § 51.166(b)(23)(i))

State Implementation Plan (SIP): A plan developed by each state to ensure attainment and maintenance of the National Ambient Air Quality Standards (NAAQS) and other Clean Air Act requirements. (42 U.S.C. § 7410)

Stationary Source: Any building, structure, facility, or installation which emits or may emit a regulated NSR pollutant. (40 C.F.R. § 51.166(b)(5))

Synthetic Minor Source: A source that has the potential to emit pollutants above major source thresholds but accepts legally enforceable limits to keep its emissions below those thresholds, avoiding major source permitting requirements. (EPA Memorandum, "Guidance on Limiting Potential to Emit in New Source Permitting," June 13, 1989)

Title V Operating Permit: A permit required for major sources and certain other sources, which consolidates all Clean Air Act requirements applicable to the source into a single, comprehensive document. (42 U.S.C. § 7661a)

Volatile Organic Compounds (VOCs): Any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. (40 C.F.R. § 51.100(s))