In this chapter, the following terms have the meanings indicated. Terms Defined. “Acceptable ambient level (AAL)” means a concentration of a toxic air pollutant in the atmosphere that the Department determines will provide a margin of safety to protect the public health from toxic, noncarcinogenic effects that may be caused by the toxic air pollutant and that is used to evaluate the air quality impacts of all premises within a 5-kilometer (3.1-mile) radius. AALs are listed in COMAR 26.11.16.09. “Allowable emissions” means the maximum emissions a source or installation is capable of discharging after consideration of any physical or operational limitations required by this subtitle or by enforceable conditions included in an applicable air quality permit to construct, permit to operate, secretarial order, plan for compliance, consent agreement, or court order. Best Available Control Technology for Toxics (T-BACT). “T-BACT” means control technology that results in the maximum degree of emission reduction that the Department determines, on a case-by-case basis, is available for each toxic air pollutant discharged by the installation, taking into account the potency and toxicity of each toxic air pollutant and the technical and economic feasibility of control. “T-BACT” includes production, operation, and maintenance procedures, emission control technology, and other emission reduction technologies or a combination of these technologies and procedures. “T-BACT”, as applicable to a MACT source, means: A requirement that has been adopted by the US EPA under 40 CFR 63 and that applies to the installation, source, source category, or subcategory; A new source MACT as established by the Department in accordance with the provisions of 40 CFR §§63.40—63.44; Alternative standard approved by the EPA Administrator; or Alternative emission limitation approved by the Department in accordance with 40 CFR Part 63, Subpart D. “Class I toxic air pollutant (Class I TAP)” means a substance or group of substances that is listed in COMAR 26.11.16.06. “Class II toxic air pollutant (Class II TAP)” means any substance that is not a Class I TAP, for which there is no ambient air quality standard under this subtitle, that is not a simple asphyxiant or nuisance particulate, and that is: A health hazard as that term is defined at 29 CFR §1915.1200 (July 1, 1994); or Listed in COMAR 26.11.16.07B as an existing source Class II TAP, either individually or as a member of a group of substances. “EPA's Risk Assessment Guidelines” means the U.S. Environmental Protection Agency's Guidelines for Carcinogenic Risk Assessment, 51 FR 33992 (September 24, 1986). “Existing installation, existing source, or existing premises” means an installation, source, or premises, respectively, constructed before July 1, 1988, or for which the Department issued an air quality permit to construct before July 1, 1988. Any existing installation that is modified but that is not reconstructed after July 1, 1988, remains an existing installation. “Hazardous air pollutant (HAP)” means any of the hazardous air pollutants listed in §112(b) of the federal Clean Air Act of 1990, 42 U.S.C. §§7401—7671. “Insignificant risk concentration (IRC)” means a concentration of a Class I toxic air pollutant in the atmosphere that would result in an excess individual lifetime cancer risk of not more than 1 in 100,000 (1 × 10 superscript -5) assuming continuous exposure for 70 years and using procedures consistent with EPA's Risk Assessment Guidelines. IRCs are listed in COMAR 26.11.16.09. “Installation” has the meaning given in COMAR 26.11.01.01, except that for purposes of this chapter, installation does not include air pollution control equipment as defined in COMAR 26.11.01.01. “MACT source” means a NESHAP source that is subject to the requirements in 40 CFR 63; “Maximum achievable control technology (MACT)”, as applicable, means: MACT emission limitation for existing sources as defined in 40 CFR §63.51; or MACT emission limitation for new sources as defined in 40 CFR §63.51. “New installation, new source, or new premises” means an installation, source, or premises, respectively, constructed or reconstructed on or after July 1, 1988, except as provided under §B(7) of this regulation. “New source MACT” means maximum achievable control technology (MACT) emission limitation for new sources as defined in 40 CFR §63.41. “Nuisance particulate” means dust that, when inhaled, causes a potentially reversible lung tissue reaction in which the architecture of the lung's air spaces remains intact, and collagen (scar tissue) is not formed to a significant extent. Examples of nuisance particulates are listed in COMAR 26.11.16.08. “Premises” means all the installations or other sources that are located on contiguous or adjacent properties and that are under the control of one person or under common control of a group of persons. “Reconstruct” means to replace components of an existing installation, or add components to an existing installation, to such an extent that the fixed capital cost of the new components exceeds 50 percent of the fixed capital cost that would be required to construct a comparable entirely new installation. Reconstruct does not include replacement or additions that do not: Cause the discharge of different toxic air pollutants; Cause applicable screening levels to be exceeded; and Increase the ambient concentration of any Class I toxic air pollutant. “Screening analysis” means an optional procedure for demonstrating compliance with Regulation .06 of this chapter that compares maximum incremental ambient impacts with applicable screening levels. “Screening level” means a concentration of a toxic air pollutant in the atmosphere used to evaluate the air quality impacts of a single premises. Screening level includes the following: “Risk-based screening level” means a concentration of a Class I toxic air pollutant in the atmosphere as determined under COMAR 26.11.16.03; “Special screening level (SSL)” means a concentration of a toxic air pollutant in the atmosphere that replaces a TLV or threshold-based screening level. Special screening levels are listed in COMAR 26.11.16.09; “TLV-based screening level” means a concentration of a Class I or Class II toxic air pollutant in the atmosphere as determined under COMAR 26.11.16.03; “Threshold-based screening level” means a concentration of a Class I or Class II toxic air pollutant in the atmosphere as determined under COMAR 26.11.16.03 when a TAP has neither a TLV-based nor a special screening level. “Second tier analysis” means an optional procedure for demonstrating compliance with Regulation .06 of this chapter using an acceptable ambient level or an insignificant risk concentration, as provided in COMAR 26.11.16.02, instead of a screening level. “Simple asphyxiant” means a physiologically inert gas or vapor that acts primarily by diluting atmospheric oxygen below the level required to maintain proper levels of oxygen in the blood. Examples of simple asphyxiants are listed in COMAR 26.11.16.08. “Threshold limit value (TLV)” means the airborne concentration of a substance that, according to the American Conference of Governmental Industrial Hygienists (ACGIH), represents conditions to which nearly all workers may be exposed without adverse effect and that is published in the chapter titled "1991—1992 Threshold Limit Values for Chemical Substances in the Work Environment" (Adopted by ACGIH with Intended Changes for 1991—1992), which is incorporated by reference. This chapter is found in the TLV booklet, defined in §B(19) of this regulation. TLV includes the following: “Ceiling TLV (TLV-C)” means a concentration that ACGIH indicates should not be exceeded even instantaneously in a workplace; “Short term exposure limit (TLV-STEL or STEL)” means a 15-minute time-weighted average concentration that ACGIH indicates should not be exceeded at any time during a workday; “Threshold limit value—time weighted average (TLV-TWA)” means a concentration recommended by ACGIH for a normal 8-hour workday and 40-hour workweek. “TLV booklet” means "1991—1992 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices" (American Conference of Governmental Industrial Hygienists, 1991). Toxic Air Pollutant. “Toxic air pollutant (TAP)” means any Class I or Class II toxic air pollutant, as defined in §B(4) and (5) of this regulation. “Toxic air pollutant” does not include particulate matter and volatile organic compounds as generic classes of substances, but an individual substance or a group of substances within either of these classes is a TAP if it meets a criterion in §B(4) or (5) of this regulation. “Upper bound unit risk factor” means the 95 percent upper confidence limit of an estimate of the extra risk of cancer associated with a continuous 70-year exposure to 1 microgram/cubic meter of a Class I toxic air pollutant.