Smoke from wildfires in the Canadian Prairies has led to air quality warnings across southern Quebec.
Swiss company IQAir this morning ranked Montreal as having the worst air quality in the world.
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Environment Canada has issued warnings that recommend limiting time spent outdoors.
It says people with existing health conditions, seniors, pregnant women, infants, and young children should avoid strenuous outdoor activities this weekend.
Heat warnings are also in effect in southern Quebec for Sunday, Monday, and Tuesday.
Temperatures are expected to top 30 degrees C during the day and remain above 20 degrees C at night.