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Sulfur Dioxide Designations

Sulfur Dioxide Designations - Where You Live

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State designations

Round 1

On July 25, 2013, EPA identified or “designated” 29 areas in 16 states as “nonattainment” for the 2010 SO2 standard.  Learn more about this action

See also: Round 1 state recommendations and EPA’s responses

Round 2

In response to court-order, EPA must complete remaining designations for the 2010 primary 1-hour SO2 standard on a schedule that contains three specific deadlines. By July 2, 2016, EPA must designate two groups of areas:

  1. areas with newly monitored violations of the 2010 primary 1-hour SO2  standard, and
  2. areas containing stationary sources that had not been announced as of March 2, 2015, for retirement and that according to EPA’s Air Markets Database emitted in 2012 either (i) more than 16,000 tons of SO2 or (ii) more than 2,600 tons of SO2 with an annual average emission rate of at least 0.45 pounds of SO2 per one million British thermal units (lbs SO2/mmBTU).

Round 2 state recommendations and EPA's responses


Tribal designations

Round 1 – no tribal areas were designated during the first round of designations for the 2010 SO2 standard.   See tribal recommendations and EPA's responses.

Round 2 – no tribal areas are expected to be impacted during the second round of designations for the 2010 SO2 standard.


Area designation maps

Round 1

Nonattainment Area Designations 

Round 2

Preliminary Area Designations for the SO2