Ill. Admin. Code tit. 35, § 243.122 - Sulfur Oxides (Sulfur Dioxide)
a) 1971
Secondary Three-Hour NAAQS for Sulfur Oxides (as SO2)
1) The level of the 1971 secondary three-hour
NAAQS for sulfur oxides is 0.5 ppm, not to be exceeded more than once per
calendar year. The three-hour averages must be determined from successive
non-overlapping three-hour blocks starting at midnight each calendar day and
must be rounded to one decimal place (fractional parts equal to or greater than
0.05 ppm must be rounded up).
2)
Sulfur oxides must be measured in the ambient air as SO2
by the FRM described in appendix A-2 to
40 CFR
50, incorporated by reference in Section
243.108,
or by an FEM designated by USEPA and listed in List of Designated Methods,
incorporated by reference in Section 243.108.
3) To demonstrate attainment, the
second-highest three-hour average must be based upon hourly data that are at
least 75 percent complete in each calendar quarter. A three-hour block average
must be considered valid only if all three hourly averages for the three-hour
period are available. If only one or two hourly averages are available, but the
three-hour average would exceed the level of the standard when zeros are
substituted for the missing values, subject to the rounding rule of subsection
(b)(1), this must be considered a valid three-hour average. In all cases, the
three-hour block average must be computed as the sum of the hourly averages
divided by three.
BOARD NOTE: This subsection (a) is derived from 40 CFR 50.5.
b) 2010 Primary One-Hour NAAQS for Sulfur
Oxides (as SO2)
1) The
level of the 2010 primary one-hour NAAQS for sulfur oxides is 75 ppb, measured
in the ambient air as SO2.
2) The 2010 one-hour primary NAAQS for sulfur
oxides is met at an ambient air quality monitoring site when the three-year
average of the annual (99th percentile) of the daily
maximum one-hour average concentrations is less than or equal to 75 ppb, as
determined in accordance with appendix T of
40 CFR
50, incorporated by reference in Section
243.108.
3) The level of the 2010
one-hour primary NAAQS for sulfur oxides must be measured by an FRM based on
appendix A-1 or A-2 of 40
CFR 50, incorporated by reference in Section
243.108, or by an FEM designated by USEPA and listed in List of Designated
Methods, incorporated by reference in Section 243.108.
Notes
Amended at 37 Ill. Reg. 19848, effective November 27, 2013
BOARD NOTE: This subsection (b) is derived from 40 CFR 50.17.
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