This page provides detailed information on designations
and classifications of 1-hour
ozone nonattainment areas, maintenance plan requirements and
anti-backsliding requirements. It reflects the current status of 1-hour nonattainment areas and
does not reflect the 8-hour standard. For information about the 8-hour ozone areas, click on
the "8-Hour Ozone" link on the left sidebar.
On June 15, 2005 the 1 hour ozone standard was revoked for all areas except the 8-hour ozone
nonattainment Early Action Compact Areas (EAC) areas (those do not yet have an effective date
for their 8-hour designations). This happened by virtue of 40 CFR 50.9(b). Due to the
revocation of the 1-hour ozone standard, effective June 15, 2005, a recent notice
[70 FR 44470] removed from 40 CFR part 81 the 1-hour designations and classifications
for all areas except EAC areas that have deferred effective dates for their designations under
the 8-hour ozone standard. The former 1-hour ozone designations and classifications as of
June 15, 2004, are being retained in subpart C of Part 81 for purposes of the anti backsliding
provisions of 40 CFR 51.905. 40 CFR 51.905(c) references subpart C of part 81 for the areas
affected by the anti-backsliding regulation.
The final phase 1 rule that implements the 8-hour ozone standard provides generally that
only the portion of the designated area for the 8-hour NAAQS that was designated nonattainment
for the 1-hour NAAQS is required to comply with the anti-backsliding obligations in 40 CFR 51.905(a).
Consult the rule for additional detail. The maintenance plans required under section
51.905(a)(3)(iii) and (4)(ii) must demonstrate maintenance only for the area designated
nonattainment (or attainment with a section 175A maintenance plan) for the 1-hour NAAQS
at the time of designation of the 8-hour NAAQS.
- Areas With 1-hour Standard to be Revoked April 15, 2009
These areas are listed in Subpart C
Fourteen areas were listed in 40 CFR Part 81 Subpart C as participating in an Early Action
Compact and designated nonattainment with a deferred effective date.
The 1-hour standard will be revoked for these areas one year after the effective date (April 15, 2008) of
their designation as attainment or nonattainment for the 8-hour ozone standard. By
April 2008, 13 of the areas were designated attainment when they met all of their EAC requirements
and had clean 8-hour ozone data by December 31, 2007. The Denver CO Subpart 1 EAC area was designated
nonattainment for 8-hour Ozone, effective November 20, 2007 (72 FR 53952)
based on air quality data from 2005, 2006 and the first three quarters of 2007.
- Area Listings Sorted by
- Classification
- State/Area/County
- Area/State/County
- Area Maps
- U.S. Map
- Area Designation Data
- Data
- Area Summary Report
History:
On February 6, 2008, EPA proposed (73 FR 6863) and on April 2, 2008, finalized (73 FR 17897)
the designation of the remaining 13 Early Action Compact (EAC) Areas as attainment
for the 8-hour ozone National Ambient Air Quality Standard (NAAQS), effective April 15, 2008.
The States in which these 13 areas are located had submitted quality-assured data indicating that the
areas are in attainment for the 8-hour ozone NAAQS based on ambient air monitoring data from 2005, 2006 and 2007.
In addition, consistent with EPA's implementing regulations, the 1-hour ozone NAAQS will no longer apply
in each of these areas one year after the effective date of the designation. The 8-hour ozone NAAQS tables will be
modified in the regulations to reflect the attainment designation for the 13 EAC areas and the 1-hour ozone NAAQS
tables in the regulations to reflect that the 1-hour standard will no longer apply in these areas as of April 15,
2009.
- Previous Nonattainment and Maintenance Areas No Longer Subject
to the 1-hour Standard (As of June 15, 2005)
- Previous Nonattainment Areas No Longer Subject
to the 1-hour Standard (As of June 15, 2005) These areas are listed in Subpart C
- Area Listings
- Classified Areas Sorted by Classification
- Sec. 185A Areas (for Sec 185A definition, click here.)
- Incomplete or No Data Areas
- Sorted by State/Area/County
- Sorted by Area/State/County
- Area Maps
- Classification by County - U.S. Map
- Individual Previous Nonattainment Area Maps
- Area Designation Data
- Classified
- Sec. 185A
- Incomplete or No Data
- Previous Nonattainment Area Summary Report
- Previous Maintenance Areas No Longer Subject to the 1-hour Standard
(As of June 15, 2005)
- Area Listings
- Classified Areas Sorted by Former Classification
- Sec. 185A Areas (for Sec 185A definition, click here.)
- Incomplete or No Data Areas
- Sorted by State/Area/County
- Sorted by Area/State/County
- Area Maps
- Classification by County - U.S. Map
- Area Designation Data
- Classified
- Sec. 185A
- Incomplete or No Data
- Previous Maintenance Area Summary Report
Two 1-hour Ozone Maintenance Areas (that were previously nonattainment areas) became
Early Action Compact (EAC) areas. As EAC areas, their maintenance plans no longer applied,
and they are not listed in the “Previous Maintenance Areas No Longer Subject to the 1-hour
Standard” reports. The areas are: Greensboro Winston Salem High Point, NC (initially classified
as a Moderate 1-hr Ozone area), and Denver Boulder, CO (initially classified as a Section 185 1-hr Ozone area).
- Areas with a Maintenance Plan Requirement Under Section 110(a)(1) of the CAA
The phase 1 final rule to implement the 8-hour ozone standard was published on April 30, 2004.
The anti backsliding provisions in that rule set forth specific requirements for areas that are
designated attainment for the 8-hour ozone standard; and that were - at the time of the 8-hour
designations (generally June 15, 2004) - either attainment areas with maintenance plans for the
1-hour standard; or nonattainment for the 1-hour standard.
Specifically, 40 CFR part 51, section 51.905(a)(3) and (4) requires these areas to submit a
maintenance plan under section 110(a)(1) of the CAA. That maintenance plan must demonstrate
maintenance out to 10 years after designation. This maintenance plan does not, however,
carry with it any conformity obligations (unlike maintenance plans required under section 175A
of the Act. The section 110(a)(1) maintenance plan must be submitted within 3 years after
designation for the 8-hour ozone standard.
- Area Listings
- Classified Areas Sorted by Classification
- Sec. 185A Areas (for Sec 185A definition, click here.)
- Incomplete or No Data Areas
- Sorted by State/Area/County
- Sorted by Area/State/County
- Area Maps
- Classification by County - U.S. Map
- Area Designation Data
- Classified
- Sec. 185A
- Incomplete or No Data
- Area Summary Report
The Maintenance Areas listed below (Previously Nonattainment Areas) which are still subject
to the 1-hour standard have maintenance plans required under section 175A, but are not at this
time subject to the Section 110(a)(1) maintenance plan provision under 40 CFR part 51, section
51.905(a)(3) and (4). When the 1-hour standard no longer applies, they will
be required to submit 110(a)(1) maintenance plans under 40 CFR part 51, section 51.905(a)(3) and (4),
if they are attainment for the 8-hour standard.
The areas are: Nashville, TN, Greensboro Winston Salem High Point, NC, and Denver Boulder, CO.
- Federal Register Notices Relating to 1-Hour Ozone Designations and Classifications
- August 3, 2005 Notice Revoking the 1-hour Standard in Most of the Nation
(Effective September 2, 2005) [ HTML ] [ PDF ]
- August 16, 2005 Correction to August 3 Notice
- Nov. 6, 1991 Federal Register Notice
- Other Associated Federal Register Notices
- Clean Air/Attainment Determinations
- Attainment Date Extensions
These extensions modify the dates shown in the nonattainment areas above
- Changes to a Higher Classification
- All Notices
- Notices Listed By Category
- Notices Listed By Area Name
- Notices Listed By State then Area
- Notices Listed By Date
- Significant Changes since the Nov. 6, 1991 Federal Register Notice
- By Category
- By Area Name
- By State
- By Date
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