Smoke from the raging wildfires in northern Minnesota drifted into parts of eastern Canada on that day . Environment Canada listed areas in Ontario among the worst globally for air quality in recent reports . Toronto faced urgent warnings about hazardous air from the distant fires . Dry conditions and fierce gusts helped wildfires spread at breakneck speed through Minnesota and nearby states. Toxic smoke drifted north, blanketing Canada in a persistent layer of contaminants.