(1) Aggregate. Any hard, inert material used for mixing in graduated particles or fragments. Includes sand, gravel, crushed stone, slag, rock dust or powder.

(2) Animal oncogenes. Chemicals for which oncogenicity has been demonstrated in at least one mammalian species.

(3) Carcinogenic to humans. Chemicals where there is convincing epidemiological evidence of a causal association between human exposure and cancer as described by the United States Environmental Protection Agency Guidelines for Carcinogen Risk Assessment.

(4) Criteria air contaminant. Particulate matter, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen dioxide. Elemental lead is a criteria air contaminant as well as a Federal hazardous air pollutant: elemental lead and lead compounds are also treated as a high toxicity air contaminant.

(5) Guideline concentrations. Ambient air concentrations that are listed in the Division of Air Resource’s Annual and Short-term Guideline Concentrations (AGC/SGC) tables.

(6) Genotoxic chemicals. Chemicals that have been shown to damage DNA or chromosomes in in-vitro and/or in-vivo short-term tests.

(7) Hot mix asphalt. Paving material that is produced by mixing hot dried aggregate with heated asphalt cement.

(8) Hot mix asphalt production plant. A facility comprised of process operations to produce paving material manufactured by mixing hot dried aggregate with heated asphalt cement.

(9) High toxicity air contaminants (HTACs). Chemicals that are carcinogenic to humans; or likely to be carcinogenic to humans; or chemicals that are known to cause adverse outcomes in humans for reproductive and developmental effects; or chemicals that elicit irreversible or progressive detrimental effects that have been observed in humans; or chemicals meeting the definition of persistent and bioaccumulative in this section; or any chemicals meeting the following LC₅₀ or LD₅₀ values:

(10) Low NO_x burner. A burner designed to reduce flame turbulence by the mixing of fuel and air and by establishing fuel-rich zones for initial combustion, thereby reducing the formation of nitrogen oxides (NO_x).

(11) Lethal dose fifty or lethal concentration fifty (LD₅₀ or LC₅₀). The median administered dose that will kill 50 percent of a tested mammalian specie.

(12) Likely to be carcinogenic in humans. Chemicals with evidence indicating oncogenicity in two mammalian species; or one mammalian species, independently reproduced; or one mammalian species, to an unusual degree with respect to incidence, latency period, site, tumor type or age at onset; or one mammalian species, supported by positive results in short-term tests which are indicative of potential oncogenic activity.

(13) Low toxicity air contaminant. Chemicals that can cause irritation or reversible effects to sensitive members of the population, and which do not meet the criteria for classification as a high toxicity or moderate toxicity air contaminants.

(14) Moderate toxicity air contaminants. Chemicals that are animal oncogenes; or chemicals that are known to cause adverse outcomes in animal species for reproductive and developmental effects; or genotoxic chemicals; or chemicals that when inhaled have caused significant chronic adverse effects in test animals, or any chemicals meeting the following LC₅₀ or LD₅₀ values:

(15) Overall removal efficiency. The total reduction of VOC emissions considering the efficiency of both the capture system and of the subsequent destruction and/or removal of these air contaminants by the control equipment prior to their release into the outdoor atmosphere.

(16) Persistent and bioaccumulative. Where chemicals that are emitted to the air persist in the environment, and are estimated to have a half-life of greater than or equal to six months in water or soil or sediments; or where chemicals have the ability to bioconcentrate or biomagnify in the food chain and have bioconcentration factors (BCFs) greater than 1,000 in fish or shellfish.

(17) Persistent and bioaccumulative (PB) trigger. A yearly mass emission limit equaling 10 times the mass emission listed in section 212-2.2 of this Part for all corresponding persistent and bioaccumulative air contaminants emitted from the facility.

(18) Process operation. Any industrial, institutional, commercial, agricultural or other activity, operation, manufacture or treatment in which chemical, biological and/or physical properties of the material or materials are changed, or in which the material(s) is conveyed or stored without changing the material(s) if the conveyance or storage system is equipped with a vent(s) and is non-mobile, and that emits air contaminants to the outdoor atmosphere. A process operation does not include an open fire, operation of a combustion installation, or incineration of refuse other than by-products or wastes from a process operation(s).

(19) Process emission source. Any apparatus, contrivance or machine, including any appurtenant exhaust system or air cleaning device capable of causing emissions of any air contaminant to the outdoor atmosphere from a process operation.

(20) Toxic - best available control technology (T-BACT). The maximum degree of reduction or the emission limitation for each non-criteria air contaminant that the department determines is achievable for a process operation on a case-by-case basis. The department will determine an achievable degree of reduction or emission limitation using the following parameters:

(21) Toxic impact assessment (TIA). An inhalation risk assessment that is supported by a protocol describing the procedures to be used to predict maximum offsite ambient air concentrations.

(22) Tune-up. Adjustments made to a burner in accordance with procedures supplied by the manufacturer (or an approved specialist) to optimize the combustion efficiency.