Smoke from Canadian wildfires is blowing into the United States and might remain for days.

Smoke from wildfires in Canada is moving into parts of the central US and could linger in the days ahead, health and weather officials warned Thursday. Air quality alerts have been posted across several states, including Nebraska, Washington, Montana and Wisconsin, with a special weather statement about air quality in Wyoming. The heaviest smoke concentrations should shift further east into the Midwest later in the day, affecting major metro areas including Chicago, Indianapolis and St. Louis. Canada has had an especially active start to the fire season, with devastating wildfires in Alberta burning more than 150 times more area than in the last five years combined. In Nebraska, the National Weather Service warned that Canadian wildfire smoke is moving through the area today through tomorrow morning, resulting in potentially dangerous air quality and poor visibility across eastern Nebraska and Iowa. The US Environmental Protection Agency’s Air Quality Index indicated parts of the Rockies, the Great Plains and the Midwest, including the Nebraska Panhandle and northeast corner of the state, had “very unhealthy” air quality early Friday.