8-Hour Ozone (2015) Nonattainment Area Summary

Data is current as of June 30, 2026

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Classification	Number of Areas	Number of Counties	2010 Population
Extreme	2	12	19,544,668
Severe 15	3	1	4,369,276
Serious	22	117	69,342,608
Moderate	6	31	14,865,543
Marginal	11	19	8,880,754
Marginal (Rural Transport)	1	1	0
SUBTOTAL	45	181	117,002,849
GRAND TOTAL	45	181	117,002,849

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