Section 243.125  Ozone

a)         2008 Primary and Secondary Eight-Hour NAAQS for Ozone

1)         The 2008 primary and secondary eight-hour NAAQS for ozone is 0.075 ppm, daily maximum eight-hour average, measured by an FRM based on appendix D to 40 CFR 50, incorporated by reference in Section 243.108, and designated by USEPA and listed in the List of Designated Methods, incorporated by reference in Section 243.108, or an FEM designated by USEPA and listed in the List of Designated Methods, incorporated by reference in Section 243.108.

2)         The 2008 primary and secondary eight-hour NAAQS for ozone ambient air quality standards are met at an ambient air quality monitoring site when the three-year average of the annual fourth-highest daily maximum eight-hour average ozone concentration is less than or equal to 0.075 ppm, as determined in compliance with appendix P to 40 CFR 50, incorporated by reference in Section 243.108.

BOARD NOTE:  This subsection (a) is derived from 40 CFR 50.15.

b)         2015 Primary and Secondary Eight-Hour NAAQS for Ozone

1)         The level of the eight-hour primary NAAQS for ozone is 0.070 ppm, daily maximum eight-hour average, measured by a reference method based on appendix D to 40 CFR 50, incorporated by reference in Section 243.108, or an equivalent method designated by USEPA and listed in the List of Designated Methods or a Federal Register notice incorporated by reference in Section 243.108.

2)         The eight-hour primary NAAQS for ozone is met at an ambient air quality monitoring site when the three-year average of the annual fourth-highest daily maximum eight-hour average ozone concentration is less than or equal to 0.070 ppm, as determined in compliance with appendix U to 40 CFR 50, incorporated by reference in Section 243.108.

3)         The level of the secondary NAAQS for ozone is 0.070 ppm, daily maximum eight-hour average ozone concentration, measured by a reference method based on appendix D to 40 CFR 50, incorporated by reference in Section 243.108, and designated by USEPA and listed in the List of Designated Methods or a Federal Register notice incorporated by reference in Section 243.108.

4)         The eight-hour secondary NAAQS for ozone is met at an ambient air quality monitoring site when the three-year average of the annual fourth-highest daily maximum eight-hour average ozone concentration is less than or equal to 0.070 ppm, as determined in compliance with appendix U to 40 CFR 50, incorporated by reference in Section 243.108.

BOARD NOTE:  This subsection (b) is derived from 40 CFR 50.19.

(Source:  Amended at 48 Ill. Reg. 8097, effective May 16, 2024)