Air Quality_Content Page_NOx RACT

Reasonably Available Control Technology (RACT) For Nitrogen Oxides (NOX)

Emissions of nitrogen oxides (NOx) must be controlled through the implementation of Reasonably Available Control Technology (RACT) regulations in ozone nonattainment areas that are classified as "moderate" or higher. Wisconsin RACT requirements that apply to NOx emissions units are listed in subchapter IV of ch. NR 428, Wis. Adm. Code.

These rules affect NOx emissions units at facilities that meet the following criteria:

  1. The facility has NOx emissions from a unit greater than a specified capacity size as identified in s. NR 428.22, Wis. Adm. Code, which includes boilers; lime kilns; reheat, annealing or galvanizing furnaces; glass furnaces; asphalt plants; process heaters; simple cycle combustion turbines; combined cycle combustion turbines; and reciprocating engines.
  2. The facility is located in an ozone National Ambient Air Quality Standard (NAAQS) nonattainment area that is currently or was previously classified as moderate, serious, severe or extreme ozone nonattainment on or after July 20, 2012. Facilities located in counties previously classified in any of the above categories continue to be subject to NOx RACT requirements even if the county is subsequently redesignated to attainment. Refer to Permitting Requirements for Nonattainment Areas to view a map of areas where NOx RACT is being implemented and the areas' nonattainment classification history.
  3. The facility's combined total maximum theoretical emissions for all NOx emissions units meet or exceed the applicability thresholds listed in the table below. The area's nonattainment classification (current or historical) associated with the lowest emission threshold determines the area’s major source applicability threshold.

Emissions Thresholds

Nonattainment Area Classification Emissions Threshold (tons per year)
Moderate 100
Serious 50
Severe 25
Extreme 10

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