Toronto had the fifth most polluted air of the world’s major cities early Tuesday morning, according to Swiss air technology company IQAir’s ranking,

The smoke from forest fires is still expected to cloud Toronto’s skies on Monday, according to Environment Canada’s special air quality statement.

Wildfires burning in Canada were causing unhealthy air quality across parts of North America on Monday. Canadian wildfires burning across northern Manitoba and Saskatchewan are sending smoke through central Canada, the Great Lakes region and the northeastern United States, reducing air quality and visibility in major cities.