Chicago's Air Quality Plummets to World's Worst Amid Canadian Wildfires

Wildfires in Quebec and Ontario have caused dense smoke to invade the Great Lakes region, with Chicago, Minneapolis, and Detroit ranking among the top 10 cities with the worst air quality in the world. Code Red conditions have been reported in many areas, with some reaching Code Purple and even Code Maroon. The primary pollutant in wildfire smoke is PM2.5, which are fine particles from burned organic matter. The smoke is expected to continue moving eastward and southward, potentially affecting the Mid-Atlantic and Northeast regions.