Smoke from the explosive forest fires in Minnesota drifted into parts of eastern Canada on a recent Wednesday . Environment Canada flagged areas in Ontario among the worst globally for air quality during this stretch. Toronto faced urgent warnings about hazardous air from the unrelenting smoke . Dry conditions and fierce gusts helped blazes spread at breakneck speed through Minnesota and nearby states. Toxic smoke drifted north, blanketing Canada in a heavy curtain of contaminants.