40 CFR § 52.690
Visibility protection
June 9, 2020
(a) The requirements of section 169A of the Clean Air Act are not met, because the plan does not include approvable procedures for protection of visibility in mandatory Class I Federal areas.
(b)-(c) [Reserved]
[50 FR 28553, July 12, 1985; 51 FR 23759, July 1, 1986, as amended at 52 FR 45137, Nov. 24, 1987; 82 FR 3129, Jan. 10, 2017]