The Minnesota Pollution Control Agency has issued an air quality alert for east central, central, west central, southeast, north central, northwest, and northeast Minnesota. The alert runs until 11:00 a.m. on Friday. The affected area includes the Twin Cities metro area, Brainerd, Alexandria, Hinckley, St. Cloud, Winona, Moorhead, International Falls, Two Harbors, Hibbing, Ely, Duluth, and the Tribal Nations of Mille Lacs, Prairie Island, Leech Lake, White Earth, Red Lake, Grand Portage, and Fond du Lac. Very heavy smoke was expected across the Arrowhead Tuesday, as large wildfires continue to spread. Hot temperatures, when combined with air pollution, will exacerbate health impacts A frontal boundary will then spread heavy smoke further south Tuesday evening in to this morning, as it moves across northern and central Minnesota. The onset of smoke will be rapid. Much of Minnesota also remains under an Extreme Heat Warning until at least 9:00 p.m. on Thursday.