ST. PAUL, Minn. — The Minnesota Pollution Control Agency is expanding its air pollution warning due to smoke from wildfires in Canada.

The agency on Monday expanded the alert previously issued for the northern two-thirds of Minnesota to include the southern, central and northeastern parts of the state. The expanded area includes the Twin Cities.

Heavy smoke from Canadian wildfires is slowly moving across Minnesota. As of 3 p.m., fine particle levels had reached unhealthy levels in a band across the state that includes Marshall, St. Cloud, Brainerd, Duluth and Grand Portage.

All areas of Minnesota are expected to see improved air quality by Tuesday morning, but smoke could return to the state that afternoon.