Six metropolises in North America appeared Friday morning in the ranking of the ten most polluted cities in the world.
Rankings from the IQAir website showed Toronto dominating this list and Montreal in eighth place.
Environment Canada also maintained warnings for these two cities, early Friday.
The other most polluted major North American cities were, in order, Washington, New York, Detroit and Chicago.
The ranking of the ten most polluted cities in Canada showed smaller municipalities. Nine of them are located in Ontario: Brampton, Uxbridge, Peterborough, Oakville, Ottawa, Newmarket, Barrie, St. Catharines and Mississauga. The other was the Quebec municipality of L’Ange-Gardien, in Outaouais.
Environment Canada warned Thursday evening that in the Toronto area, smoke from forest fires raging in northeastern Ontario and Quebec is expected to cause poor air quality and reduced visibility, possibly up to to Saturday, Canada Day.