You are here: EPA Home > Green Book > 8-Hour Ozone (1997) Maintenance Area (Redesignated from Nonattainment) Summary - NAAQS Revoked
8-Hour Ozone (1997) Maintenance Area (Redesignated from Nonattainment) Summary - NAAQS RevokedData is current as of May 31, 2023
The 1997 8-hour Ozone NAAQS was revoked effective April 6, 2015 (80 FR 12264).
|Classification||Number of Areas||Number of Counties||2010 Population|
|Former Subpart 1||56||136||22,506,809|
|Subpart 1 EAC||0||0||0|
County subtotals and grand totals may not equal sum of parts. Part counties are only counted one time across groupings. Multi-state nonattainment areas are not considered maintenance areas until all states in the area have been redesignated.
On June 8, 2007, the United States Court of Appeals vacated the Subpart 1 portion of the Phase 1 Rule (Court Order) (PDF). On May 14, 2012, the Former Subpart 1 nonattainment areas were classified under Subpart 2 (77 FR 28424 ) (PDF), effective June 13, 2012.