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WI DNR Proposes New Rule to Align our State’s Ambient Air Quality Standard for NO2 and SO2

The Wisconsin DNR is proposing a new rule to align our state’s ambient air quality standard for nitrogen dioxide (NO2) and sulfur dioxide (SO2) with the corresponding federal standards under the Clean Air Act.  As you may recall, the U.S. EPA recently approved new, more stringent standards for both of these pollutants:

  • In 2010, the EPA finalized a new hourly NO2 standard at 100 parts per billion (ppb).  This new standard is in addition to the annual NO2 standard of 53 ppb.
  • Last year, the EPA replaced the 24-hour SO2 standard of 140 ppb with a much more stringent hourly standard at 75 ppb.

Moving to hourly standards for these pollutants is very likely to result in actual or predicted air quality violations, which in turn will lead to more costly and complex air permitting activities.  As a result, the proposed rule is likely to increase the operating costs for businesses with NO2 or SO2 emissions.
Because of a new law (2011 Act 21) that WMC advocated for last session, state agencies like the DNR are now required to study the economic impact of proposed rule before the rules are finalized.  Included in the new law is a requirement that agencies solicit information about the cost of proposed rules directly from businesses and organizations like WMC that represent businesses.
The DNR has asked for WMC’s help with quantifying the cost of this proposed rule.  As a WMC member, you are in a unique position to assist in quantifying the potential costs of the rule.  For some businesses, the costs may be significant, as the new standards may drive the need for pollution control retrofits at their facility.  For other businesses, the increased cost will result from additional air dispersion modeling required to demonstrate compliance with the new standards during air permitting activities.
WMC will collect economic cost feedback from members in an effort to help the DNR estimate the anticipated costs for the rule.  As always, no information specific to any individual companies will be shared with the DNR.
Please consider responding to this message with information about how your company may be impacted by this rule.  You can contact me directly at (608) 258-3400 or if you have any questions.
NOx & SO2 Rule




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