On September 5, 2025, the U.S. Court of Appeals for the Seventh Circuit issued an order staying the EPA’s December 17, 2024, final rule that determined parts of southeast Wisconsin failed to attain the 2015 ozone national ambient air quality standards (NAAQS), and consequently would be reclassified from “moderate” to the more restrictive “serious” nonattainment category. That reclassification was effective January 16, 2025, impacting portions of southeastern Wisconsin—specifically, Milwaukee and Ozaukee counties and parts of Waukesha, Washington, Racine, Kenosha, and Sheboygan counties.

The reclassification imposed much more stringent requirements on sources in southeast Wisconsin emitting NOx and VOCs (precursors for ozone). Redesignation to serious nonattainment for ozone meant stationa

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