40 CFR § 51.913
How do the section 182(f) NOX exemption provisions apply for the 8-hour NAAQS?
June 9, 2020
(a) A person may petition the Administrator for an exemption from NOX obligations under section 182(f) for any area designated nonattainment for the 8-hour ozone NAAQS and for any area in a section 184 ozone transport region.
(b) The petition must contain adequate documentation that the criteria in section 182(f) are met.
(c) A section 182(f) NOX exemption granted for the 1-hour ozone standard does not relieve the area from any NOX obligations under section 182(f) for the 8-hour ozone standard.
[70 FR 71701, Nov. 29, 2005]