PORTLAND, Maine >> Smoke from Canadian wildfires started making air quality worse in the eastern U.S. on Wednesday as several Midwestern states battled conditions deemed unhealthy by the federal government.

The fires have forced thousands of Canadians to flee their homes and sent smoke as far as Europe.

In the U.S., smoke lingered on the skylines of cities from Kansas City to Minneapolis, and a swath of the region had unhealthy air quality Wednesday, according to an Environmental Protection Agency map.

In Stoughton, Wisconsin, Nature’s Garden Preschool was keeping its kids indoors Wednesday due to the bad air quality, which interferes with the daily routine, said assistant teacher Bailey Pollard. The smoke looked like a coming storm, he said.

The 16 or 17 kids ages 12 weeks to 5 years would typically be outdoors running or playing with water, balls and slides, but were instead inside doing crafts with Play-Doh or coloring. The situation was unfortunate because kids need to be outside and have fresh air and free play, Pollard said.

“It’s something where we’ve got to take precaution for the kids,” he said. “Nobody wants to stay inside all day.”

Iowa issued a statewide air quality alert through early Thursday, urging residents to limit certain outdoor activities and warning of possible health effects due to the thick smoke.