§52.121. Classification of regions.
40 C.F.R. § 52.121
The Arizona plan is evaluated on the basis of the following classifications:
Notes, amendments, and revision history
Amendments
[83 FR 42219, Aug. 21, 2018, as amended at 89 FR 71835, Sept. 4, 2024; 90 FR 59056, Dec. 18, 2025]
Authority
Authority: 42 U.S.C. 7401 et seq.
Amendments
[40 FR 5521, Feb. 6, 1975]
Amendments
[83 FR 42219, Aug. 21, 2018, as amended at 89 FR 71835, Sept. 4, 2024; 90 FR 59056, Dec. 18, 2025]