Ozone (O3) Air Quality Designations

All National Ambient Air Quality Standards (NAAQS) undergo periodic review and may be revised to reflect the latest health, environmental and technological advances. When a new standard is promulgated or an existing standard is revised for ozone, the first step in implementation is to determine which areas are, or are not, violating the NAAQS or are contributing to a violation of the NAAQS. During the “designation process,” states submit ambient air quality monitoring data and designation recommendations, which the United States Environmental Protection Agency (U.S. EPA) reviews and considers before issuing final designations. IDEM’s map of Indiana Ozone Nonattainment Designations [PDF] shows current air quality designations for all counties. Following are documents relating to U.S. EPA’s air quality designations in Indiana for the ozone NAAQS.

2015 8-Hour Ozone Standard

U.S. EPA issued air quality designations for the 2015 ozone standards in two rounds. In the first round on November 6, 2017, U.S. EPA addressed most areas of the U.S. At that time, U.S. EPA stated it was not yet ready to issue designations for remaining areas and intended to address them in a future, separate action. U.S. EPA issued a second round of designations on April 30, 2018, for remaining areas that were not addressed in the first round.

• Documents – October 7, 2022 to September 16, 2016 [ZIP]
  • Federal Register Notice, U.S. EPA Reclassification from “Marginal” to “Moderate” for Indiana’s Portion of the Chicago, Illinois-Indiana-Wisconsin Nonattainment Area (October 7, 2022)
  • Federal Register Notice Concerning Revised Air Quality Designations for the 2015 8-Hour Ozone National Ambient Air Quality Standards (NAAQS) (June 14, 2021)
  • Federal Register Notice Concerning U.S. EPA’s Air Quality Designations for the 2015 8-Hour Ozone National Ambient Air Quality Standard; Corrections (October 16, 2018)
  • Federal Register Notice Concerning Additional Air Quality Designations for the 2015 8-Hour Ozone National Ambient Air Quality Standard (June 4, 2018)
    • U.S. EPA Technical Support Information for the Chicago, IL-IN-WI Area
    • U.S. EPA Technical Support Information for the Cincinnati, OH-KY-IN Area
    • U.S. EPA Technical Support Information for the Louisville, KY-IN Area
  • Indiana’s Response to U.S. EPA’s Intended Designations for Remaining Areas of Indiana under the 2015 8-Hour Ozone National Ambient Air Quality Standard (February 16, 2018)
  • U.S. EPA’s Proposed Designation Recommendations for Remaining Areas of the State under the 2015 8-Hour Ozone National Ambient Air Quality Standard (NAAQS) (December 20, 2017)
  • Federal Register Notice Concerning Round 1 Ozone Designations, (November 16, 2017)
  • U.S. EPA Final Round 1 Designations Under the 2015 8-Hour Ozone National Ambient Air Quality Standard (NAAQS) (November 6, 2017)
  • Indiana’s Recommendations Including Transmittal Letter and Enclosures 1-3 (September 16, 2016)

2008 8-Hour Ozone Standard

• Reclassification – Moderate to Serious:
  • Document – August 23, 2019 [ZIP]
    • Federal Register Notice, U.S. EPA Reclassification from “Moderate” to “Serious” for the Chicago-Naperville, Illinois-Indiana-Wisconsin Nonattainment Area including Lake and Porter Counties (August 23, 2019)
• Reclassification – Marginal to Moderate:
  • Document – May 4, 2016 [ZIP]
    • Federal Register Notice, U.S. EPA Reclassification from “Marginal” to “Moderate” for the Chicago-Naperville, Illinois-Indiana-Wisconsin Nonattainment Area including Lake and Porter Counties (May 4, 2016)
• Documents - August 10, 2012 to April 13, 2012 [ZIP]
  • IDEM Petition for U.S. EPA Administrator Reconsideration of Final Rule for Lake and Porter Counties (August 10, 2012)
  • IDEM Issue Briefing Concerning Designations for Lake and Porter Counties Under the 2008 Ozone Standard (July 30, 2012)
  • Federal Register Notice Concerning U.S. EPA Final Designations Under the 2008 Ozone Standard for Several Counties in Illinois, Indiana (Greater Chicago Area), and Wisconsin (June 11, 2012)
  • Federal Register Notice Concerning U.S. EPA Final Designations under the 2008 Ozone Standards, Implementation of the 2008 Ozone Standards, Nonattainment Area Classifications Approach, Attainment Deadlines and Revocation of the 1997 Ozone Standards for Transportation Conformity Purposes (May 21, 2012)
  • Indiana’s Response to U.S. EPA 120-Day Letter, Transmittal Letter, Enclosure 1 and Appendices A-D (April 13, 2012)
    • Appendix E (Pennsylvania Area Consistency Evaluation)
    • Appendix E (Tennessee, Illinois-Indiana-Wisconsin, Ohio, and Louisiana Area Consistency Evaluations)
    • Appendix F and Enclosures 2-4
• Documents - January 31, 2012 to December 9, 2011 [ZIP]
  • U.S. EPA Revisions to Preliminary Response to Indiana’s 2008 Ozone Nonattainment Recommendations (January 31, 2012)
  • U.S. EPA Preliminary Response to Indiana’s 2008 Ozone Nonattainment Recommendations (December 9, 2011)
• Documents - March 11, 2009
  • Part 1 [ZIP]
    • Indiana’s Recommendations for Air Quality Designations under the 2008 8-Hour Ozone Standards, Transmittal Letter and Enclosures 1-4
      • Enclosure 4, Appendix A
      • Enclosure 4, Appendix B
  • Part 2 [ZIP]
    • Enclosure 4, Appendix C-Part 1
    • Enclosure 4, Appendix C-Part 2

Previous Ozone Standards

U.S. EPA’s Green Book provides information concerning designations under previous standards:

• 1997 8-Hour Ozone NAAQS
• 1979 1-Hour Ozone NAAQS

IDEM’s Nonattainment Status for Indiana Counties page includes additional nonattainment history.