Smoke from the explosive forest fires in northern Minnesota drifted into Ontario on the current stretch of days. Environment Canada reported areas in Ontario among the worst globally for air quality on some days . Toronto faced urgent warnings about hazardous air from the distant fires . Prolonged dryness and howling winds helped fires spread at breakneck speed through Minnesota and nearby states. Toxic smoke drifted north, blanketing Canada in a thick veil of contaminants.