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Technology Transfer Network / NAAQS
Ozone Implementation

Areas Affected by Reinstatement of the 1-hour Ozone Standard

Information provided for informational purposes onlyNote: EPA no longer updates this information, but it may be useful as a reference or resource.


EPA is proposing to reinstate the 1-hour ozone standard in areas where the standard had been revoked. EPA had previously revoked the 1-hour standard in 2,945 counties(1) (or parts of counties) that had attained the standard based on monitoring at least 3 years of clean air. There are currently 33 areas (198 counties) where the 1-hour standard has continued to apply and they are not affected by the reinstatement action.

Areas Designated As Attainment with No Violations Since Revocation

Includes 2,820 counties that have been in attainment of the 1-hour standard since 1990 or were previously nonattainment and redesignated to attainment prior to EPA's determination that the 1-hour standard no longer applied.

Areas Designated Attainment (Without Maintenance Plans) With Violations Since Revocation

Includes 4 counties currently violating the 1-hour standard based on 1996-98 data.

  • Berrien Co., MI (part of Benton Harbor)

  • Hamilton Co., IN (part of Indianapolis)

  • Hamilton Co., TN (part of Chattanooga)

  • Rowan Co., NC (part of Charlotte)

Areas Designated Attainment (With Maintenance Plans) With Violations Since Revocation

Includes 7 areas (24 counties) currently violating the 1-hour standard based on 1996-1998 data.

  • Charlotte-Gastonia, NC (2 counties)

  • Huntington-Ashland, WV-KY (4 counties)

  • Knoxville, TN (1 county)

  • Nashville, TN (5 counties)

  • Portland-Vancouver AQMA, OR-WA (4 counties)

  • Richmond, VA (7 counties)

  • Sheboygan, WI (1 county)

Areas Designated Nonattainment With No Violations Since Revocation

Includes 45 areas (96 counties) that are not violating the 1-hour standard based on 1996-98 data.


  • Boston-Lawrence-Worcester (E. MA), MA-NH (12 counties)

  • Portsmouth-Dover-Rochester, NH (1 county)

  • Providence (All RI), RI (5 counties)


  • Atlantic City, NJ (2 counties)

  • Knox & Lincoln Cos., ME (2 counties)

  • Lewiston-Auburn, ME (2 counties)

  • Muskegon, MI (1 county)

  • Portland, ME (3 counties)

  • Poughkeepsie, NY (3 counties)


  • Albany-Schenectady-Troy, NY (6 counties)

  • Allentown-Bethlehem-Easton, PA-NJ (4 counties)

  • Altoona, PA (1 county)

  • Buffalo-Niagara Falls, NY (2 counties)

  • Door Co., WI

  • Erie, PA (1 county)

  • Essex Co., NY

  • Harrisburg-Lebanon-Carlisle, PA (4 counties)

  • Jefferson Co., NY

  • Johnstown, PA (2 counties)

  • Manchester, NH (1 county)

  • Reno, NV (1 county)

  • Scranton-Wilkes-Barre, PA (5 counties)

  • Smyth Co., VA (White Top Mtn)

  • York, PA (2 counties)

  • Youngstown-Warren-Sharon, OH-PA (3 counties)

SECTION 185A AREAS (Section 185A areas, previously called transitional areas, had 3 complete years of clean data from 1987-89)

  • Chico, CA (1 county)

  • Denver-Boulder, CO (6 counties)

  • Flint, MI (1 county)

  • Yuba City, CA (2 counties)

INCOMPLETE DATA CLASSIFICATION (Incomplete data areas had no data or less than 3 complete years of data at time of classification)

  • Allegan Co., MI

  • Cheshire Co., NH

  • Crawford Co., PA

  • Franklin Co., PA

  • Greene Co, PA

  • Juniata Co., PA

  • Lawrence Co., PA

  • Northumberland Co., PA

  • Pike Co., PA

  • Saginaw-Bay City-Midland, MI (3 counties)

  • Salem, OR (2 counties)

  • Schuylkill Co., PA

  • Snyder Co., PA

  • Susquehanna Co., PA

  • Warren Co., PA

  • Wayne Co., PA

Areas Designated Nonattainment With Violations Since Revocation

Includes only 1 county currently violating the 1-hour standard based on 1996-98 data.


  • Sussex Co., DE

1. In this context the term "county" covers only those counties in the United States of America, excluding the U.S. territories of Puerto Rico, Virgin Islands, and American Somoa. The 2,945 county total includes 36 independently recognized cities in Virginia.

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