On May 26, 2021, the U.S. Environmental Protection Agency (EPA) published its final decision expanding the boundaries of ozone non-attainment areas for sixteen counties in the states of Wisconsin, Illinois, Indiana and Missouri. The decision specifically relates to the 2015 National Ambient Air Quality Standards (NAAQS) for ozone and affects the following eastern Wisconsin counties: Milwaukee, Ozaukee, Racine, Waukesha, Washington, Sheboygan, Manitowoc and Door. These newly designated areas will be subject to more stringent Clean Air Act requirements that could limit opportunities for economic growth and development.