DES MOINES – Exceedances of the National Ambient Air Quality Standards (NAAQS) for fine particulates are expected today and tomorrow over most of the state. Smoke from wildfires in northwestern Canada has converged over Iowa and is expected to lead to fine particulate matter exceedances over most of the state today.
The smoke is expected to remain over the area and affect air quality until about midnight Saturday night, with possible residual effects extending into early Sunday. While continuous monitors for fine particulate recorded exceedances of the NAAQS across almost all of Iowa on Thursday, the final results will not be available until filters from federal reference monitors have been manually weighed. Wildfire smoke carries large amounts of particulates as well as gases that may act as ozone precursors and can lead to exceedances of the NAAQS for both fine particulate matter and ozone.
The national standard for fine particulate matter is 35 micrograms per cubic meter (µg/m3) averaged over a 24-hour period, and this level is considered “unhealthy for sensitive groups.” Groups sensitive to particulate matter include people with heart or lung disease, older adults, children and teenagers, and outdoor workers. Fine particulate levels will likely reach levels considered “unhealthy” where even healthy adults should consider limiting their activities.
Real-time air quality maps and information about the air quality index can be found on EPA’s airnow.gov site. A graphic approximation of the extent and trajectory of the smoke plume can be seen on the map at fire.airnow.gov. EPA’s specific guidelines on what precautions can be taken to minimize the impact of high ozone and fine particulate levels are available at: https://www.airnow.gov/publications/activity-guides-publications/. In general, these guidelines involve limiting outdoor activities, especially prolonged outdoor exertion.