(2) In determining air purity standards, the commission shall consider the following factors:

(a) The quality or characteristics of air contaminants or the duration of their presence in the atmosphere which may cause air pollution in the particular area of the state;

(b) Existing physical conditions and topography;

(c) Prevailing wind directions and velocities;

(d) Temperatures and temperature inversion periods, humidity, and other atmospheric conditions;

(e) Possible chemical reactions between air contaminants or between such air contaminants and air gases, moisture or sunlight;

(f) The predominant character of development of the area of the state, such as residential, highly developed industrial area, commercial or other characteristics;

(g) Availability of air-cleaning devices;

(h) Economic feasibility of air-cleaning devices;

(i) Effect on normal human health of particular air contaminants;

(j) Effect on efficiency of industrial operation resulting from use of air-cleaning devices;

(k) Extent of danger to property in the area reasonably to be expected from any particular air contaminants;

(L) Interference with reasonable enjoyment of life by persons in the area which can reasonably be expected to be affected by the air contaminants;

(m) The volume of air contaminants emitted from a particular class of air contamination source;

(n) The economic and industrial development of the state and continuance of public enjoyment of the state’s natural resources; and

(o) Other factors which the commission may find applicable.

(3) The commission may establish air quality standards including emission standards for the entire state or an area of the state. The standards shall set forth the maximum amount of air pollution permissible in various categories of air contaminants and may differentiate between different areas of the state, different air contaminants and different air contamination sources or classes thereof.

(4) The commission shall specifically fulfill the intent of the policy under ORS 468A.010 (1)(a) as it pertains to the highest and best practicable treatment and control of emissions from stationary sources through the adoption of rules:

(a) To require specific permit conditions for the operation and maintenance of pollution control equipment to the extent the Department of Environmental Quality considers the permit conditions necessary to insure that pollution control equipment is operated and maintained at the highest reasonable efficiency and effectiveness level.

(b) To require typically achievable control technology for new, modified and existing sources of air contaminants or precursors to air contaminants for which ambient air quality standards are established, to the extent emission units at the source are not subject to other emission standards for a particular air contaminant and to the extent the department determines additional controls on such sources are necessary to carry out the policy under ORS 468A.010 (1)(a).

(c) To require controls necessary to achieve ambient air quality standards or prevent significant impairment of visibility in areas designated by the commission for any source that is a substantial cause of any exceedance or projected exceedance in the near future of national ambient air quality standards or visibility requirements.

(d) To require controls necessary to meet applicable federal requirements for any source.

(e) Applicable to a source category, contaminant or geographic area necessary to protect public health or welfare for air contaminants not otherwise regulated by the commission or as necessary to address the cumulative impact of sources on air quality.

(5) Rules adopted by the commission under subsection (4) of this section shall be applied to a specific stationary source only through express incorporation as a permit condition in the permit for the source.

(6) Nothing in subsection (4) of this section or rules adopted under subsection (4) of this section shall be construed to limit the authority of the commission to adopt rules, except rules addressing the highest and best practicable treatment and control.

(7) As used in this section, "typically achievable control technology" means the emission limit established on a case-by-case basis for a criterion contaminant from a particular emission unit in accordance with rules adopted under subsection (4) of this section. For an existing source, the emission limit established shall be typical of the emission level achieved by emission units similar in type and size. For a new or modified source, the emission limit established shall be typical of the emission level achieved by recently installed, well controlled new or modified emission units similar in type and size. Typically achievable control technology determinations shall be based on information known to the department. In making the determination, the department shall take into consideration pollution prevention, impacts on other environmental media, energy impacts, capital and operating costs, cost effectiveness and the age and remaining economic life of existing emission control equipment. The department may consider emission control technologies typically applied to other types of emission units if such technologies can be readily applied to the emission unit. If an emission limitation is not feasible, the department may require a design, equipment, work practice or operational standard or a combination thereof. [Formerly 449.785 and then 468.295; 1993 c.790 §1]