On June 22, 2010, U.S. EPA strengthened the National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (SO₂). U.S. EPA set a new one-hour primary SO₂ standard at 75 ppb and revoked the existing annual and 24-hour primary standards (for which Ohio had been in full attainment).

• Map of the 2010 one-hour SO2 nonattainment areas

On August 21, 2015 U.S. EPA published the final Data Requirements Rule for the 2010 SO2 standard. [80 FR 51052] This rule required Ohio EPA to characterize SO2 emissions around sources not located in nonattainment areas but with the potential to impact compliance with the 2010 SO2 standard. This characterization was either through monitoring or modeling. Based upon the DRR, under 40 CFR 51.1203, each state was required to submit a list of applicable SO2 sources identified pursuant to 40 CFR 51.1202 by January 15, 2016. 

• January 15, 2016 Letter of DRR Sources
• July 1, 2016 Letter of DRR Sources with chosen air quality characterization pathway

Nonattainment Area Recommendation

Annual Emissions Reviews

The August 21, 2015 Data Requirements Rule for the 2010 SO2 standard [80 FR 51052] established ongoing data review requirements including, for areas where modeling of actual SO2 emissions served as the basis for an unclassifiable/attainment designation, an annual review of emissions data and submittal of a report recommending whether updated modeling is necessary due to emissions increases. The annual emissions review is due to U.S. EPA Region 5 by July 1, annually, beginning the calendar year after the effective date of designation.

• 2017 annual emissions review
• 2018 annual emissions review
• 2019 annual emissions review
• 2020 annual emissions review
• 2021 annual emissions review 
• 2022 annual emissions review

Attainment Demonstration

Redesignations and Maintenance Plans