Chicago air quality remains in the top five worst in the world Friday with an Air Quality Alert in place from Canadian wildfire smoke.

Smoke from wildfires blazing across Canada is once again wafting over huge portions of the U.S. Midwest and worsening air quality there. On August 1 conditions are particularly bad in Minnesota, Iowa and Illinois.

The smoke is expected to remain over the northern and central Plains of the United States for the next couple of days, according to meteorologists.