Wildfire smoke from Canada is blanketing the skies in the Midwest, leaving millions with dangerous breathing conditions.

Smoke from wildfires blazing across Canada is once again wafting over huge portions of the Midwest and worsening air quality, with conditions particularly bad on August 1 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.