The Iowa Department of Natural Resouces (DNR) announced Saturday morning that fine particulate (PM2.5) levels near federal health standards were expected in northern and central Iowa all day Saturday.
The source of the air pollution is a plume of smoke originating from Canadian wildfires and passing southward through the state. The smoke plume caused a spike in fine particle levels in northern Iowa this morning, according to the DNR, and the condition might persist into Saturday afternoon or evening.
The DNR recommends that prolonged outdoor exertion be avoided by individuals in northern and central Iowa with heart or lung disease, the elderly and children until the smoke plume passes and air quality conditions improve.
Iowans can keep track of evolving air quality conditions at the DNR air quality website.
The federal standard for human exposure to airborne particulate matter is set by the U.S. Environmental Protection Agency (EPA). The EPA’s 24-hour health threshold for PM2.5 is 35 micrograms per cubic meter (µg/m3).
The DNR reported that at noon Saturday, one-hour concentrations were above 36 µg/m3 in much of northern and central Iowa. Hourly levels in Des Moines, Emmetsburg, Iowa City, Muscatine and Cedar Rapids were 206, 152, 98, 80, and 62 µg/ m3 respectively.
Averages so far Saturday for these sites are 16, 107, 30, 24, and 29 µg/ m3 respectively. Levels are expected to drop later this afternoon or early this evening, the DNR said.