Indiana Administrative Code › Title 326 - AIR POLLUTION CONTROL DIVISION › Article 1 - GENERAL PROVISIONS › Rule 3 - Ambient Air Quality Standards › Section 3-4 - Ambient air quality standards

Current through July 10, 2024
Authority: IC 13-14-8; IC
				  13-17-3-4;
				  IC
				  13-17-3-11
Affected: IC 13-15; IC 13-17
Sec. 4.
(a) All
				measurements of air quality that are expressed as mass per unit volume, other
				than for the particulate matter (PM2.5) standards
				contained in subsection (b)(8) and lead (Pb) standards contained in subsection
				(b)(6), must be corrected to a reference temperature of twenty-five (25)
				degrees Celsius and a reference pressure of seven hundred sixty (760)
				millimeters of mercury (one thousand thirteen and two-tenths (1,013.2)
				millibars), as micrograms per cubic meter
				(µg/m3). Measurements of
				PM2.5, for purposes of comparison to the standards
				contained in subsection (b)(8), and Pb, for purposes of comparison to the
				standards contained in subsection (b)(6), must be reported based on actual
				ambient air volume measured at the actual ambient temperature and pressure at
				the monitoring site during the measurement period.
(b) Ambient air quality standards are as
				follows:
(1) Sulfur oxides as sulfur dioxide
				(SO2) requirements are as follows:
(A) For the primary one (1) hour ambient air
				quality standard, the maximum permissible ambient air quality level is
				seventy-five (75) parts per billion (ppb). The one (1) hour standard is
				attained when the three (3) year average of the annual ninety-ninth percentile
				of the daily maximum one (1) hour average concentration is less than or equal
				to seventy-five (75) ppb, as determined in accordance with 40 CFR 50, Appendix
				T* and measured in the ambient air as SO2 by a reference
				method based on 40 CFR 50, Appendix A-1* or 40 CFR 50, Appendix A-2*, or an
				equivalent method designated in accordance with 40 CFR 53 *.
(B) For the secondary standard, the following
				value represents the maximum permissible ambient air quality level: one
				thousand three hundred (1,300) µg/m3
				(five-tenths (0.5) ppm) maximum three (3) hour concentration not to be exceeded
				more than once per year. The three (3) hour averages must be determined from
				successive nonoverlapping three (3) hour blocks starting at midnight each
				calendar day and must be rounded to one (1) decimal place (fractional parts
				equal to or greater than five-hundredths (0.05) ppm must be rounded up). Sulfur
				oxides must be measured in the ambient air as SO2 by the
				reference method described in 40 CFR 50, Appendix A-1* or 40 CFR 50, Appendix
				A-2*, or by an equivalent method designated in accordance with 40 CFR 53 *. To
				demonstrate attainment, the second-highest three (3) hour average must be based
				upon hourly data that are at least seventy-five percent (75%) complete in each
				calendar quarter. A three (3) hour block average is considered valid if:
(i) all three (3) hourly averages for the
				three (3) hour period are available; or
(ii) only one (1) or two (2) hourly averages
				are available, but the three (3) hour average would exceed the level of the
				standard when zeros are substituted for the missing values, subject to the
				rounding rule of this clause. In all cases, the three (3) hour block average
				must be computed as the sum of the hourly averages divided by three
				(3).
(C)
				SO2 values may be converted to ppm using the conversion
				factor two thousand six hundred twenty (2,620) µg/m3
				  = one (1) ppm.