Sulfur Dioxide Designations - Regulatory Actions
Round 4 Area Designations
EPA Supplemental Amendment for the Fourth Round of SO2 Area Designations
April 8, 2021 - EPA modified one of its area designations for the 2010 sulfur dioxide (SO2) primary National Ambient Air Quality Standard (NAAQS). Learn more about the April 8, 2021 action.
Final Round of SO2 Area Designations
December 21, 2020 - After reviewing all available data and information, EPA completes the final round of area designations. Learn more .
Intended Area Designations
August 13, 2020 - EPA is responding to state recommendations by announcing the Agency's fourth round of intended area designations. EPA’s letters to state governors will initiate a 120-day period for states to provide additional information, if desired, to inform our final designations. EPA is also opening a 30-day public comment period for interested parties to provide input on these designations. The Agency intends to finalize these designations by December 31, 2020. Learn more about the August 13, 2020 action.
Round 3 Area Designations
EPA Redesignates Portions of Westmoreland and Cambria Counties, PA for the 2010 SO2 NAAQS.
December 17, 2024 - EPA is redesignating as “nonattainment” certain portions of Westmoreland and Cambria Counties, Pennsylvania to address modeled violations of the 2010 SO2 NAAQS. Learn more about the December 17, 2024 action.
EPA Supplemental Amendment for the Third Round of SO2 Area Designations
March 28, 2018 - EPA is withdrawing the designation of Unclassifiable for the Citrus County, Florida, area that the EPA originally issued on December 21, 2017, and establishing a designation of Attainment/Unclassifiable. Learn more about the March 28, 2018 action.
EPA Completes Third Round of SO2 Area Designations
December 21, 2017 - After reviewing all available data and information, EPA is completing a third round of area designations. Learn more about the December 21, 2017 action.
Intended Area Designations
August 22, 2017 - In response to recommendations from state and tribal representatives, EPA has sent letters to state and tribal leaders outlining the area designations the agency intends to complete by December 31, 2017, for the 2010 primary standard for sulfur dioxide. Learn more about the August 22, 2017 action.
Round 2 Area Designations
EPA Redesignates Two Unclassifiable Areas One in Texas and One in Nebraska
June 30, 2021 - Date - EPA is redesignating as “attainment/unclassifiable” an area in Nebraska, and an area in Texas. Learn more about the June 30, 2021 action.
EPA Responds to Administrative Petitions and Withdraws Proposed Error Correction for Areas in Texas
June 24, 2021- EPA is denying two petitions for reconsideration and two requests for administrative stay of its 2016 nonattainment designations for certain areas in Texas. Additionally, EPA is withdrawing its August 2019 proposed error correction. Learn more about the June 24, 2021 action.
Proposed Redesignation of Certain Unclassifiable Areas
August 6, 2020 - EPA is proposing to redesignate as “attainment/unclassifiable” certain “unclassifiable” areas in Missouri, Ohio, Nebraska, and Texas. When these areas were initially designated, EPA did not have sufficient information to determine if they attained the 2010 1-hour health-based National Ambient Air Quality Standard for Sulfur Dioxide. Learn more about the August 6, 2020 action.
EPA Finalizes Reconsideration of Nonattainment Designation for Williamson County, Illinois
September 5, 2019- EPA finalizes action in response to petition for reconsideration. Learn more about the September 5, 2019 action.
EPA Proposes Error Correction of Designations for Areas in Texas
August 13, 2019- EPA proposes action in response to petitions regarding portions of Freestone and Anderson Counties, Rusk and Panola Counties, and Titus County in Texas. Learn more about the August 13, 2019 action.
EPA Proposes Reconsideration of Nonattainment Designation for Williamson County, Illinois
May 28, 2019 - EPA proposes action in response to petition for reconsideration. Learn more about the May 28, 2019 action.
EPA Responds to Reconsideration Requests for Areas in Texas
September 21, 2017 - EPA responds to a petition requesting action on area designations in Texas. Learn more about the September 21, 2017 action for Texas.
EPA Responds to Petition for Error Correction for Williamson County, Illinois
September 21, 2017 - EPA responds to a petition requesting action on area designations in Illinois. Learn mor about the September 21, 2017 action for Illinois.
EPA Responds to Reconsideration Requests for Areas in Illinois, Missouri and Ohio
January 18, 2017 - EPA is taking action on three petitions requesting the Agency to reconsider certain area designations for the 2010 health based sulfur dioxide air quality standard. Learn more about the January 18, 2017 action.
EPA Supplements Second Round of SO2 Area Designations
November 29, 2016 - EPA supplements second round area designations with additional designations for Texas. Learn more about the November 29, 2016 action.
EPA Completes Second Round of SO2 Area Designations
June 30, 2016 - After reviewing all available data and information, EPA is completing a second round of area designations. Learn more about the June 30, 2016 action.
Intended Area Designations
February 17, 2016 - In response to recommendations from state and tribal representatives, EPA has sent letters to state and tribal leaders outlining the area designations the agency intends to complete by July 2, 2016, for the 2010 primary standard for sulfur dioxide. Learn more about the February 17, 2016 action.
Round 1 Area Designations
EPA Completes Initial Round of SO2 Nonattainment Designations
July 25, 2013 - After reviewing input on initial nonattainment designations, EPA is designating parts of 16 states as nonattainment for the 2010 sulfur dioxide standard. EPA will address the designations for all other areas in separate actions in the future. Learn more about the July 25, 2013 action.
Recommendations for Areas to be Designated “Nonattainment” for the 2010 National Air Quality Standard for Sulfur Dioxide
February 7, 2013 - In response to recommendations from state and tribal representatives, EPA sent letters to state and tribal leaders outlining the areas it is considering designating as “nonattainment” for the 2010 primary standard for sulfur dioxide. Learn more about the February 7, 2013 action.
EPA Extends Date of Designations for 2010 Primary SO2 Standard
July 27, 2012 - EPA is extending the deadline for area designations for the 2010 primary SO2 standard by up to 1 year due to having insufficient information to make initial area designations at this time. With this extension, EPA is required to complete initial designations by June 3, 2013. Learn more about the July 27, 2012 action.