(a) What is the purpose of this section? This section limits the amount of particulate matter that may be emitted from certain air pollution sources operating within the Indian reservation to control ground-level concentrations of particulate matter.

(b) Who is affected by this section? This section applies to any person who owns or operates an air pollution source that emits, or could emit, particulate matter to the atmosphere, unless exempted in paragraph (c) of this section.

(c) What is exempted from this section? This section does not apply to woodwaste burners, furnaces and boilers used exclusively for space heating with a rated heat input capacity of less than 400,000 British thermal units (Btu) per hour, non-commercial smoke houses, sweat houses or lodges, open burning, and mobile sources.

(d) What are the particulate matter limits for air pollution sources? (1) Particulate matter emissions from a combustion source stack (except for wood-fired boilers) must not exceed an average of 0.23 grams per dry standard cubic meter (0.1 grains per dry standard cubic foot), corrected to seven percent oxygen, during any three-hour period.

(2) Particulate matter emissions from a wood-fired boiler stack must not exceed an average of 0.46 grams per dry standard cubic meter (0.2 grains per dry standard cubic foot), corrected to seven percent oxygen, during any three-hour period.

(3) Particulate matter emissions from a process source stack, or any other stack not subject to paragraph (d)(1) or (d)(2) of this section, must not exceed an average of 0.23 grams per dry standard cubic meter (0.1 grains per dry standard cubic foot) during any three-hour period.

(e) What is the reference method for determining compliance? The reference method for determining compliance with the particulate matter limits is EPA Method 5. A complete description of this method is found in appendix A of 40 CFR part 60.

(f) Definitions of terms used in this section. The following terms that are used in this section are defined in § 49.123 General provisions: Act, air pollutant, air pollution source, ambient air, British thermal unit (Btu), coal, combustion source, distillate fuel oil, emission, fuel, fuel oil, gaseous fuel, heat input, incinerator, marine vessel, mobile sources, motor vehicle, nonroad engine, nonroad vehicle, open burning, particulate matter, PM10, PM2.5, process source, reference method, refuse, residual fuel oil, solid fuel, stack, standard conditions, stationary source, uncombined water, used oil, wood, wood-fired boiler, and woodwaste burner.