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Important Notes for the:
Nonattainment Status for Each County by Year Report

These state/county reports list the annual nonattainment and maintenance status of each county by designated area name by National Ambient Air Quality Standard (NAAQS). Any county not listed has been designated attainment since 1992. There can be multiple rows for a county for a NAAQS if different parts of a county falls within the boundaries of separate areas.

(See the "Whole or Part County Nonattainment Status by Year for All Criteria Pollutants" report for the summarized nonattainment status of a county potentially within multiple areas for a single NAAQS.)

"Nonattainment in Year" refers to the calendar year, and reflects the area's nonattainment status as of the date of the report. For older NAAQS, many areas were nonattainment before 1992 but the 1992 starting year is based on 40 CFR Part 81 designations, effective January 6, 1992.
See: 40 CFR Part 81 (165 pp, 9.3 MB, About PDF)

For the newer NAAQS, the designation dates for original areas were:
  • 8-Hour Ozone (2015) areas were designated August 3, 2018
  • 8-Hour Ozone (2008) areas were designated July 20, 2012
  • PM-2.5 (2012) areas were designated April 15, 2015
  • PM-2.5 (2006) areas were designated December 14, 2009
  • PM-2.5(1997) areas were designated April 5, 2005
  • SO2 (2010) areas were designated October 4, 2013
  • Lead (2008) areas were designated December 31, 2010

Revoked NAAQS include 1-Hour Ozone (1979), 8-Hour Ozone (1997), and attainment and maintenance areas for PM-2.5 (1997). The 8-Hour Ozone (1997) classified areas were designated on June 15, 2004 and were revoked on April 6, 2015. 1-Hour Ozone (1979) areas were revoked on June 15, 2005. The Primary Annual PM-2.5 (1997) NAAQS (level of 15 µg/m3) was revoked in attainment and maintenance areas for that NAAQS. For additional information see the PM-2.5 NAAQS SIP Requirements Final Rule, effective October 24, 2016. (81 FR 58009)
Counties in Revoked NAAQS areas have "NAAQS revoked" appended to the NAAQS description.

A blank cell for a year indicates either the area the county is in: 1) was not designated nonattainment for that NAAQS, 2) had been redesignated to maintenance, or 3) is for a NAAQS that was revoked prior to that year.

The column "Classification" is the latest area classification. A county could have had a different classification in the past.

The column "Whole or Part County" indicates whether only a part of the county or the whole county is/was designated in the nonattainment area.

On June 8, 2007, the United States Court of Appeals vacated the Subpart 1 portion of the 1997 8-Hour Ozone Phase 1 Rule (Court Order). On May 14, 2012, the Former Subpart 1 1997 8-Hour Ozone nonattainment areas were classified under Subpart 2 ( 77 FR 28424), effective June 13, 2012.

See the following pages for details about changes in the designation status of the nonattainment areas: