TORONTO/NEW YORK: Toronto’s air quality ranked the worst among major cities globally on Wednesday as wildfire smoke from northwestern Ontario blackened skies and spread into the northeastern United States, prompting health warnings and calls for residents to limit outdoor activities. Environment Canada reported an Air Quality Health Index (AQHI) reading of 10+, classified as “very high risk,” for Toronto, while forecasts suggested hazardous conditions could persist through Thursday night.

As of Tuesday night, just under 200 total active wildfires have been reported, according to the province.

Environment Canada has issued health warnings after sky over city turns yellow