Smoke from the raging wildfires in northern Minnesota drifted into southern Ontario on a recent Wednesday . Environment Canada flagged areas in Ontario among the worst globally for air quality in recent reports . The region’s urban centers faced urgent warnings about hazardous air from the drifting haze. Extreme drought and howling winds helped wildfires spread at breakneck speed through Minnesota and nearby states. Harmful air drifted north, blanketing Canada in a persistent layer of contaminants.