Sulfur Dioxide (1971) Maintenance Area (Redesignated from Nonattainment) Summary

Data is current as of April 30, 2025

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Designation	Number of Areas	Number of Counties	2010 Population
Primary	31	36	8,511,308
Primary, Secondary	10	7	366,892
Secondary	6	6	257,662
SUBTOTAL	47	49	9,135,862
GRAND TOTAL	47	49	9,135,862

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