R 336.1228 Requirement for lower emission rate than required by best available control technology for toxics (T-BACT) and health-based screening levels.

Rule 228. (1) The department may determine, on a case-by-case basis, that the maximum allowable emission rate determined in R 336.1224(1) or R 336.1225(1) to (3) does not provide adequate protection of human health or the environment. In this case, the department shall establish a maximum allowable emission rate considering relevant scientific information, such as exposure from routes other than direct inhalation, synergistic or additive effects from other toxic air contaminants, and effects on the environment. In performing these evaluations and determinations, the department shall utilize relevant environmental data, land use, and exposure scenarios, and reasonably anticipated environmental impacts and exposures from the proposed new or modified emission unit or units. (2) The director may determine on a case-by-case basis that an emission rate limitation is needed for a non-toxic air contaminant for which there is no national ambient air quality standard in order to ensure that air emissions do not cause injurious effects to human health. The director shall make this case-by-case determination subsequent to a presentation by the air quality division and the permit applicant that utilizes relevant environmental data, land use, and exposure scenarios, and reasonably anticipated environmental impacts and exposures from the proposed new or modified emission unit or units. The department shall establish this emission rate consistent with the provisions of R 336.1225, R 336.1227, and R 336.1229 or any other methodology determined by the department to be more appropriate after an evaluation conducted under R 336.1228(1).