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1. Revised SO₂ (2010 Standard) Designation Notices
   1. Extension of Deadline for Promulgating Designations for the 2010 Primary Sulfur Dioxide NAAQS (August 3, 2012)
      See 77 FR 46295
   
   
   2. Air Quality Designations for the 2010 Sulfur Dioxide (SO₂) Primary NAAQS (August 5, 2013)
      See 78 FR 47191
   
   
   3. Air Quality Designations for the 2010 Sulfur Dioxide (SO₂) Primary NAAQS - Round 2 (July 12, 2016)
      See 81 FR 45039
   
   
   4. Air Quality Designations for the 2010 Sulfur Dioxide (SO2) Primary National Ambient Air Quality Standard - Supplement to Round 2 for Four Areas in Texas: Freestone and Anderson Counties, Milam County, Rusk and Panola Counties, and Titus County Air Quality Designations for the 2010 Sulfur Dioxide (SO₂) Primary NAAQS - Round 2 (December 13, 2016)
      See 81 FR 89870
   
   
   5. Air Quality Designations for the 2010 Sulfur Dioxide (SO₂) Primary NAAQS - Round 3 (January 9, 2018)
      See 83 FR 1098
   
   
   6. Reconsideration of the Area Designation for the 2010 1-Hour Sulfur Dioxide (SO₂) Primary National Ambient Air Quality Standard for Williamson County, Illinois (September 13, 2019)
      See 84 FR 48286