Effective August 1, 2016, the Wisconsin Department of Natural Resources (WDNR) revised the state implementation plan (SIP) to adopt the federal National Ambient Air Quality Standards (NAAQS) for sulfur dioxide (SO2) and nitrogen dioxide (NO2) for the 1-hour averaging period.  These standards are shown below:

  • 0.075 ppm (196 µg/m3) SO2 primary 1-hour average concentration
  • 0.100 ppm (188 µg/m3) NO2 primary 1-hour average concentration

These standards were originally promulgated by the EPA in 2010, but were never incorporated into the state SIP.  Modeling to demonstrate compliance with the 1-hour standards may now be required for certain construction and operation permit actions moving forward.

The WDNR is looking for input on the implementation of these standards through the permitting process and will take comments through the end of September.  Comments can be sent to Kristin Hart.  The WDNR plans on addressing public comments and implementing additional guidance and tools throughout the rest of this year.

The adoption of the NO2 standard may be an additional permitting hurdle for sources with high short-term (hourly) emissions of nitrogen oxides (NOx) or SO2, such as reciprocating internal combustion engines and other combustion sources.  If your facility has not modeled for compliance with the 1-hr NO2 or SO2 NAAQS, or if you have questions on how this might impact your facility, please contact Jon Frost at (651) 275-9900 x6.  Also, expect updates on any new WDNR guidance and tools on the Trinity Consultants website and in future newsletters.