Implementation of the Revoked 1997 8-Hour Ozone National Ambient Air Quality
Standards; Updating Federal Regulations to Show Areas that Attained by the Attainment

Date

FACT SHEET

ACTION

• On July 12, 2021, the U.S. Environmental Protection Agency (EPA) issued a final rule to
update regulations that apply to the approval and promulgation of implementation plans (40
CFR part 52) This codifies the Agency's findings that nine areas attained the revoked 1997
ozone National Ambient Air Quality Standards (NAAQS) by their respective attainment

dates:



1.

Buffalo-Niagara Falls, New York;

2.

Jamestown, New York;

3.

Jefferson County, New York;

4.

Poughkeepsie, New York;

5.

Shoreline Sheboygan County, Wisconsin;

6.

Inland Sheboygan County, Wisconsin;

7.

Denver-Boulder-Greeley-Ft. Collins-Loveland, Colorado;

8.

San Francisco Bay Area, California; and,

9.

Ventura County, California.

•	Publishing these determinations confirms for the public and state air agencies that these areas
attained the standards by the applicable attainment dates and are therefore not subject to
reclassification and other anti-backsliding consequences for failure to timely attain the
standards. The affected states' air agencies were informed of these determinations in
February 2019.

BACKGROUND

•	On July 18, 1997, EPA established the NAAQS for 8-hour average ozone concentrations at a
level of 0.08 parts per million (ppm) for both the primary and secondary standards.
Subsequently, EPA designated areas around the country as either attaining ("attainment") or
not attaining ("nonattainment").

•	On March 27, 2008, EPA revised the 8-hour ozone NAAQS to a more protective level of
0.075 ppm for both the primary and secondary standards. In April 2015, EPA issued
implementing regulations for the revised NAAQS (2008 ozone SIP Requirements Rule). In
that rule, the EPA revoked the 1997 ozone NAAQS and established requirements to ensure
that progress toward clean air would not "backslide." EPA also stated that it would no longer
make determinations of attainment by the attainment date except to trigger relevant anti-
backsliding obligations, as the designations and classifications for 1997 ozone NAAQS areas
were revoked along with the standard.

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•	In South Coast Air Quality Management District v. EPA (882 F.3d 1138 (D.C. Cir. 2018))
(known as the South Coast II decision), the U.S. Court of Appeals for the District of
Columbia Circuit vacated certain portions of the 2008 ozone SIP Requirements Rule, and
held that EPA must reclassify areas that failed to attain the revoked 1997 ozone NAAQS by
the area's applicable attainment date.

•	In February 2019, EPA regional offices issued letters to the affected states' air agencies
identifying the areas that attained the revoked 1997 ozone NAAQS by the applicable
attainment dates. The findings were based on certified quality-assured air quality monitoring
data from the 3 calendar years preceding the respective attainment dates.

•	On October 9, 2020, EPA published the proposal for this final rule. At the same time, EPA
also published a direct final rule to codify its findings, but withdrew the final notice in
December 2020 after receiving adverse comment on the proposal.

•	This final rule addresses the comments received on the proposal and updates the regulations
at 40 CFR part 52 to reflect the Agency's earlier findings.

FOR MORE INFORMATION

•	To download this action from the EPA's website, go to https://www.epa.gov/ozone-
pollution/1997-ozone-national-ambient-air-qualitv-standards-naaqs-nonattainment-actions.

•	This action and other associated information are also available electronically at
http://www.regulations.gov.

•	For further information about this final action, contact Ms. Virginia Raps in the EPA's Office
of Air Quality Planning and Standards, at (919) 541-4383 or by email at
raps.virginia@epa.gov.

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