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Sulfur Dioxide Designations

EPA Completes Third Round of Sulfur Dioxide Designations

On December 21, 2017, the U.S. Environmental Protection Agency (EPA) took an additional step to implement the health-based national air quality standard for sulfur dioxide (SO2) set in 2010. EPA has identified or “designated” areas:
  • “nonattainment” – not meeting the 1-hour health-based national air quality standard for SO2 (six areas in three states and two territories),
  • “unclassifiable” – not enough information to make a determination (23 areas in ten states), or
  • “attainment/unclassifiable” - meeting the standard and not contributing to a violation of the standard (all remaining areas except where additional SO2 air quality monitoring is underway).

Read the Federal Register Notice:  Air Quality Designations for the 2010 Sulfur Dioxide (SO2) Primary National Ambient Air Quality Standard - Round 3

Read the Technical Support Documents supporting this action.

Note: On March 28, 2018, the EPA withdrew the designation of Unclassifiable for the Citrus County, Florida, area that the EPA originally issued on December 21, 2017, and established a designation of Attainment/Unclassifiable for that area. Learn More

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