Ontario wildfires drive Toronto's air quality to the world's worst level

A series of wildfires in Ontario has severely degraded air quality in Toronto. Measurements show the city now has the worst air quality among major global cities. The Guardian reports the situation on July 15, 2026. Smoke from the fires has spread across the Greater Toronto Area. Residents are advised to limit outdoor activity and use masks. Health officials warn of increased respiratory risks. Authorities are monitoring the fires and air quality indices continuously. The episode highlights the broader impact of climate‑related events on urban health.