OAR 340-246-0150: Prioritizing and Selecting Geographic Areas

(1) DEQ will prioritize geographic areas by considering the total cancer and non-cancer risk from toxic air contaminants to the population in the area, as indicated by: (a) The number and degree of ambient benchmark concentration exceedances; (b) The toxicity or potency of toxic air contaminants exceeding ambient benchmark concentrations; (c) The level of exposure and number of people at risk in areas of concern; (d) The presence of sensitive populations; (e) The effectiveness of local control strategies; and (f) To the extent known, the risk posed by multiple pollutants and pollutant mixtures. (2) Not later than 18 months after the first set of benchmarks is adopted, DEQ will select the first geographic area for toxic air contaminants reduction planning. DEQ will base selection on representative monitoring compared to the ambient benchmark concentrations at public receptors. To the extent possible, geographic areas will be identified using monitoring data generated following EPA monitoring guidelines. Subsequent geographic areas will be selected after completion of monitoring. A geographic area is formally selected upon publication of a notice in the Oregon Secretary of State's Bulletin. Once an area is selected for toxic air contaminants reduction planning, it will retain the status of a selected geographic area until DEQ determines through an evaluation of data that a reduction plan is no longer necessary for the area to meet all toxic air contaminant ambient benchmark concentrations. (3) DEQ will first select for emissions reduction planning the high priority geographic areas, where concentrations of toxic air contaminants are more than ten times above the ambient benchmark concentrations or above a hazard quotient of one with the potential for serious adverse health effects. DEQ will select all other geographic areas, where toxic air contaminant concentrations are above benchmarks, after toxic air contaminant emissions reduction plans have been approved for the high priority geographic areas. (4) Geographic Area Boundaries. DEQ will establish general geographic area boundaries on a neighborhood or urban area scale. DEQ will consider feasibility of administration when setting the boundaries of a geographic area. In setting geographic area boundaries, DEQ will consider criteria including but not limited to the following: (a) Areas of impact (where people are exposed); (b) Population density; (c) Areas of influence (where sources are located); (d) Meteorology; (e) Geography and topography; (f) Including all toxic air contaminants exceeding ambient benchmark concentrations; and (g) Coordination with criteria pollutant boundaries for attainment of the National Ambient Air Quality Standards (NAAQS). [NOTE: Publications referenced are available from the agency.]