The US EPA, in an April 12, 2012 letter to DENR Secretary Dee Freeman, outlined EPA’s next steps for implementation of the 1-hour primary National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (SO2) promulgated in June 2010.

In the letter EPA identified several actions it will take:

  • EPA will move forward with area designations as soon as possible. It is analyzing and responding to recommendations made by state and tribal leaders made in June 2011 and expect to issue letters in the near future.
  • EPA will initiate focused stakeholder outreach to help refine the approach for determining whether air quality in a given area is meeting the SO2 NAAQS. EPA is requesting input on monitoring, modeling, and implementation issues, particularly for areas that will be designated as "unclassifiable."
  • EPA does not expect state's June 2013 State Implementation Plans (SIP) submittals to contain modeling demonstrations showing attainment of the standard in unclassifiable areas, as was outlined in the final SO2 NAAQS rule and described further in the draft implementation guidance.

EPA has now set up an outreach process that allows for focused discussion of monitoring, modeling and implementation issues. This effort will ensure that the agency has the information it needs to protect public health from unhealthy levels of SO2 in the outdoor air. EPA's SO2 implementation website ( has been updated with the current outreach and other related information.

EPA is convening three small group meetings with stakeholders to discuss issues associated with implementation of the SO2 standard. These issues will be outlined in a white paper that will be available in mid-May 2012.

Schedule for stakeholder discussions

  • Session 1: Environmental and Public Health Organization Representatives
    May 30, 2012, Washington, DC
  • Session 2: State and Tribal Representatives
    May 31, 2012, Research Triangle Park, NC
  • Session 3: Industry Representatives
    June 1, 2012, Research Triangle Park, NC

EPA will provide a summary of key comments from the stakeholder meetings following the conclusion of all three meetings. For more information about these meetings or if you are interested in attending, please contact Carolyn Childers at (919) 541-5604 or