Smoke from the more than 700 wildfires burning in Canada is continuing to blanket parts of the Midwest for a final day.

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.

Wildfire smoke from Canada turned Chicago into one of the world’s most polluted metro areas as the Lollapalooza music festival began.