340-246-0030 Definitions The definitions in OAR 340-200-0020, 340-218-0030, 340-244-0030, OAR 340-247-0020 and this rule apply to this division. If the same term is defined in this division and elsewhere, the definition in this division applies. (1) "Ambient benchmark concentration" means the concentration of a toxic air contaminant in outdoor air that would result in an excess lifetime cancer risk level of one in a million (1 x 10-6) or a non-cancer hazard quotient of one and is numerically equivalent to the “Toxicity Reference Value” as defined under OAR 340 247-0020. (2) "Geographic area" means an area identified by DEQ where toxic air contaminant concentrations are estimated or measured at levels that exceed ambient benchmark concentrations. (3) "Hazard quotient" means the ratio of the potential exposure to a single toxic air contaminant to the reference concentration for that pollutant. If the hazard quotient is calculated to be less than or equal to 1, then no adverse health effects are expected as a result of exposure. If the hazard quotient is greater than 1, then adverse health effects are possible. (4) "High priority geographic area" means an area identified by DEQ where toxic air contaminant concentrations are estimated or measured at levels that exceed ambient benchmark concentrations and pose excess cancer risk above ten in a million, or non-cancer risk above a hazard quotient of one with the potential for serious adverse health effects. (5) "Public receptor" means any outdoor area where members of the public have unrestricted access, including but not limited to residences, institutions (e.g. schools, hospitals), industrial, commercial, or office buildings, parks, recreational areas, public lands, streets or sidewalks. (6) "Reference concentration" means an estimate of a continuous exposure or a daily exposure to the human population (including sensitive populations) that is likely to be without an appreciable risk of adverse non-cancer effects during a lifetime. The reference concentration can be derived from various types of human or animal data, with uncertainty factors generally applied to reflect limitations of the data used. (7) "Sensitive human populations" means humans with increased susceptibility to the adverse effects of toxic air contaminants, including humans in prenatal or postnatal periods of development. (8) "Source" means: (a) An activity conducted by a person at a point, area, on-road mobile, or off-road mobile operation that emits toxic air contaminants; or (b) Any building, structure, facility, installation or combination thereof that emits or is capable of emitting air contaminants to the atmosphere, is located on one or more contiguous or adjacent properties and is owned or operated by the same person or by persons under common control. The term includes all pollutant emitting activities that belong to a single major industrial group (i.e., that have the same two-digit code) as described in the Standard Industrial Classification Manual , (U.S. Office of Management and Budget, 1987) or that support the major industrial group. (9) "Source Category" means: (a) A source or group of sources that emit toxic air contaminants due to the use of the same or similar processes, including commercial, residential, public or private processes, which as a group can reduce toxic air contaminant emissions by employing similar control or prevention strategies or; (b) All the pollutant emitting activities that belong to the same industrial grouping (i.e., that have the same two-digit code) as described in the Standard Industrial Classification Manual , (U.S. Office of Management and Budget, 1987). [Publications: Publications referenced are available from the agency.] Statutory/Other Authority: ORS 468.020, 468.035, 468A.010(1), 468A.015, 468A.025 & 468A.135 Statutes/Other Implemented: ORS 468.035, 468A.010(1), 468A.015, 468A.025 & 468A.135 History: DEQ 18-2021, amend filed 11/17/2021, effective 11/17/2021 DEQ 187-2018, amend filed 05/14/2018, effective 05/14/2018 DEQ 15-2003, f. & cert. ef. 11-3-03