The Missouri Department of Natural Resources, Air Pollution Control Program invites the public to review and offer written comments on the Exceptional Events Demonstration for St. Louis Area until Oct. 17, 2025. Written comments may be submitted by mail to the Missouri Department of Natural Resources, Air Pollution Control Program, ATTN: Air Quality Planning Section Chief, P.O. Box 176, Jefferson City, MO 65102-0176 or by email to apcpsip@dnr.mo.gov. Comments submitted by email are limited to 20 MB in size. Comments larger than 20 MB need to be submitted by mail to the address above or call 573-751-4817 to make other arrangements. The public can review the demonstration below.
The exceptional event is the collective of the 2023 Canadian wildfires, which started in March 2023 and continued through the end of the year. During the year, those fires burned over 42 million acres of Canada. Those wildfires affected both ozone and particulate matter less than 2.5 microns (PM2.5) monitoring concentrations for an extended period across the entire upper Midwest region of the country, including the entirety of the St. Louis area. The Exceptional Events Demonstration requests that the U.S. Environmental Protection Agency (EPA) agree with excluding ozone and PM2.5 concentrations on specific days from regulatory decisions regarding attainment of the ozone and PM2.5 National Ambient Air Quality Standards for the St. Louis area, according to the Clean Air Act Section 319(b). The department will consider and respond to all comments received before submitting the final demonstration to EPA.