Smoke from more than 100 active wildfires in northern Ontario have made Toronto’s air quality the current worst in the world and caused yellow, smoky air in cities across the north-east US.

Environment Canada issued health warnings on Wednesday after the sky over country’s largest city turned a sickly yellow and was ranked the worst in the world according to IQAir, the Swiss technology company that racks global air quality.

The city is also suffering a heatwave that shattered a three-decade record after reaching 37.3C in the downtown core, with runways at its main international airport hitting 55C.

The wildfires burning across northwestern Ontario have prompted mandatory evacuations from a number of First Nations communities.

An orange haze has washed over Toronto’s skyline as wildfire smoke drifts into the region, leaving Toronto with some of the worst air quality in the world on Wednesday.

Meanwhile, CN Rail employees in northern Ontario have been evacuated as a viral social media video shows a wildfire surrounding a train.

The video, which was taken inside the train, shows raging flames around it. A crew member can be seen also capturing the incident on their cellphone.

The train car was stopped in Armstrong, Ont., which is north of Thunder Bay. A CN Rail spokesperson told Global News all employees in the area were evacuated overnight Monday.

“CN has temporarily suspended rail operations near Armstrong, ON as a precaution due to wildfire activity in the area. As a safety measure, CN employees in the area and residents of the Town of Armstrong were evacuated overnight,” the spokesperson said in an email.

Source: The Guardian