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Sulfur Dioxide (SO2) Attainment Demonstrations

This page is dedicated to attainment demonstrations for the sulfur dioxide (SO2) National Ambient Air Quality Standards (NAAQS). An attainment demonstration describes measures Indiana is taking to improve air quality and achieve the NAAQS in areas that did not meet the standards when United States Environmental Protection Agency (U.S. EPA) issued designations.

IDEM submits attainment demonstrations to U.S. EPA according to requirements in the federal Clean Air Act (CAA) at Title I, Part D, Subpart 1, Section 172. Once a nonattainment area meets CAA requirements, IDEM asks U.S. EPA to redesignate the area to attainment status. IDEM’s Nonattainment Status of Counties page contains a map of current nonattainment areas and historical information.

Following are attainment demonstrations IDEM has prepared and submitted to U.S. EPA for review under the SO2 standards.

2010 Primary 1-Hour SO2 Standard

Daviess, Marion, Morgan, Pike and Vigo Counties
  • Documents - August 17, 2020 to May 2, 2016 [ZIP]:
    • Federal Register Notice Concerning U.S. EPA Approval and Promulgation of the 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document for the Southwest, Indiana Nonattainment Area (August 17, 2020)
    • Federal Register Notice Concerning U.S. EPA Approval and Promulgation of the 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document for the Morgan County, IN Nonattainment Area (September 23, 2019)
    • Federal Register Notice Concerning U.S. EPA Approval and Promulgation of the 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document for the Indianapolis and Terre Haute, Indiana Nonattainment Areas (March 22, 2019)
    • Supplement to the 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document for the Morgan County, IN Nonattainment Area (February 8, 2019)
    • Clarification Letter to U.S. EPA Regarding Revisions to the Indiana State Implementation Plan for Sulfur Dioxide and the Final 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document (TSD) for Central, West Central, and Southwest Indiana Nonattainment Areas (November 15, 2017)
    • Technical Addendum for Revisions to the Indiana State Implementation Plan for Sulfur Dioxide and the Final 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document (TSD) for Central, West Central, and Southwest Indiana Nonattainment Areas (May 2, 2016)
  • Revisions to the Indiana State Implementation Plan for Sulfur Dioxide and the Final 1-Hour Sulfur Dioxide Attainment Demonstration and Technical Support Document (TSD) for Central, West Central, and Southwest Indiana Nonattainment Areas (October 2, 2015)
    • Part 1 [ZIP]:
      • Transmittal Letter and Attachments A-J
      • Attachment K Including Appendix A
    • Part 2 [ZIP]:
      • Appendices B-D (Attachment K)
      • Appendix E (Attachment K)
      • Appendices F-J (Attachment K) and Attachment L