2008 Ozone National Ambient Air Quality Standards (NAAQS) Nonattainment Actions

Final Determinations of Attainment by the Attainment Date, Extension of the Attainment Date, and Reclassification of Areas Classified as Serious for the 2008 Ozone National Ambient Air Quality Standards

September 16, 2022 - As required by the Clean Air Act, EPA  finalized actions for six nonattainment areas classified as Serious for the 2008 ozone National Ambient Air Quality Standards (NAAQS). This rulemaking will ensure that smog-affected communities achieve healthy air and implement the measures that the Clean Air Act requires to protect public health in these areas.  Learn more about the final determinations.

Proposed Determinations of Attainment by the Attainment Date, Extension of the Attainment Date, and Reclassification of Areas Classified as Serious for the 2008 Ozone National Ambient Air Quality Standards

EPA held a virtual public hearing on this proposal on May 9, 2022. 

April 12, 2022 - EPA proposed determinations as to whether seven areas have achieved levels of harmful ground-level ozone pollution (or “smog”) that meet the 2008 health-based air quality standards for ozone (National Ambient Air Quality Standards or NAAQS). This rulemaking, which is required by the Clean Air Act, is necessary to ensure that smog-affected communities achieve healthy air and implement the measures that the Clean Air Act requires to protect public health in these areas.

The areas addressed in this proposal are currently classified as “Serious” nonattainment, and were required to attain the standards by July 20, 2021. Within six months after this attainment date, Clean Air Act (CAA) section 181(b)(2) requires EPA to determine whether these areas attained the standard by the attainment date, and if not, take specified actions to ensure these areas achieve attainment expeditiously. EPA based these determinations on the most recent publicly available and certified ozone monitoring data, from the years 2018-2020.  Read the proposal and a summary fact sheet below:

Proposed Determinations of Attainment by the Attainment Date, Extension of the Attainment Date, and Reclassification of Areas Classified as Serious for the 2008 Ozone National Ambient Air Quality Standards (pdf) (325 KB)

Fact Sheet: Determinations of Attainment by the Attainment Date, Extension of the Attainment Date, and Reclassification of Areas Classified as Serious for the 2008 Ozone National Ambient Air Quality Standards (pdf) (200.03 KB)

Hoja informativa: Determinaciones de logros propuestas para la fecha de cumplimiento, extensión de la fecha de cumplimiento y reclasificación de varias áreas clasificadas como de gravedad para los Estándares nacionales para la calidad de aire ambiental 2008 para el ozono. 

Findings of Failure to Submit State Implementation Plan Revisions in Response to the 2016 Oil and Natural Gas Industry Control Techniques Guidelines for the 2008 Ozone National Ambient Air Quality Standards (NAAQS) and for States in the Ozone Transport Region 

October 29, 2020 - EPA is finding that California, Connecticut, New York, Pennsylvania, and Texas failed meet the Clean Air Act deadline to submit complete State Implementation Plan (SIP) revisions that satisfy the Oil and Natural Gas Industry Control Techniques Guidelines (CTG) reasonably available control technology requirement for the 2008 ozone National Ambient Air Quality Standard (NAAQS).  The required SIP revisions were due on October 27, 2018 and apply to certain nonattainment areas and the states in the ozone transport Region (OTR). EPA is committed to working with California, Connecticut, New York, Pennsylvania, and Texas to expedite the development and submission of their state plan revisions and to ensure continued progress toward cleaner air.

Proposed Action Finding the Denver Area Failed to Attain the 2008 Ozone National Ambient Air Quality Standard and Reclassification

August 8, 2019- As required by the Clean Air Act, EPA Region 8 has proposed action for the Denver Area classified as Moderate for the 2008 ozone National Ambient Air Quality Standards. This area was required to attain the standard by July 20, 2018.

Final Determinations of Attainment by the Attainment Date, Extensions of the Attainment Date, and Reclassification of Several Areas Classified as Moderate for the 2008 Ozone National Ambient Air Quality Standards

August 7, 2019 - EPA took final actions for 11 nonattainment areas classified as Moderate for the 2008 ozone National Ambient Air Quality Standards.

Proposed Determinations of Attainment by the Attainment Date, Extensions of the Attainment Date, and Reclassification of Several Areas Classified as Moderate for the 2008 Ozone National Ambient Air Quality Standards

November 7, 2018 - As required by the Clean Air Act, EPA has proposed actions for 11 nonattainment areas classified as Moderate for the 2008 ozone National Ambient Air Quality Standards. These areas were required to attain the standards by July 20, 2018. 

Final Actions on State Implementation Plan Components for the 2008 Ozone Air Quality Standards

November 29, 2017 - This final action finds that three states failed to submit timely state implementation plan (SIP) revisions necessary to satisfy certain Clean Air Act (CAA) and EPA requirements for implementing the 2008 ozone NAAQS. Specifically, this action applies to nonattainment areas reclassified in 2016 to Moderate nonattainment after failing to attain the NAAQS by the Marginal area attainment date of July 20, 2015.

February 3, 2017 - This final action finds that 15 states and the District of Columbia have failed to submit specific state implementation plan (SIP) elements to satisfy certain nonattainment area, and/or Ozone Transport Region (OTR), planning requirements for the 2008 ozone National Ambient Air Quality Standards (NAAQS).

Final Actions on Marginal Nonattainment Areas for the 2008 Ozone Standards
May 4, 2016 –  EPA made final determinations for whether the 36 nonattainment areas originally classified as Marginal for the 2008 ozone standards met the standards by the Clean Air Act established attainment date of July 20, 2015.

Proposed Actions on Marginal Nonattainment Areas for the 2008 Ozone Standards
August 27, 2015 – EPA is proposing to take one of three actions for the 36 areas designated as nonattainment and classified as marginal for the 2008 ozone standards and is requesting comment on two options for establishing the submittal deadline for State Implementation Plans (SIP) revisions due for the reclassified areas.

Implementing the 2008 8-hour Ozone National Ambient Air Quality Standards
March 6, 2015 – EPA finalized the SIP Requirements Rule, which establishes the requirements that state, tribal, and local air quality management agencies will need to meet as they develop implementation plans for areas where air quality exceeds the 2008 National Ambient Air Quality Standards (NAAQS) for ground-level ozone.

Proposed Withdrawal of the Determination that Compliance with Regional Emissions Trading Programs meets Clean Air Act Requirements to Control Emissions for the 1997 Ozone and Fine Particle Air Quality Standards
June 9, 2014 - EPA proposed a rule that would revise how emission controls for power plants should be treated in state plans to attain the 1997 ozone and fine particle air quality standards.

Final Approach for Establishing Nonattainment Area Classifications and Attainment Deadlines
May 21, 2012 - Final rule directs key aspects of the implementation of the 2008 National Ambient Air Quality Standards (NAAQS) for ground-level ozone. The portions of this final rule involving attainment deadlines and revoking the 1997 NAAQS for purposes of transportation conformity were vacated by the D.C. Circuit Court in NRDC v. EPA (12/23/2014).

Ground-level Ozone Pollution

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Last updated on March 13, 2025