CANADIANS UNDER AIR QUALITY WARNING AS WILDFIRE BURNS.(PHOTO).

Canadians Under Air Quality Warning As Wildfire Burns

Tens of millions of people in North America have woken up to dangerous air quality levels as intense wildfires burn across Canada.

Smoke blanketed large areas of Ontario and Quebec, while an orange haze hung over much of the north-eastern US throughout Tuesday and into Wednesday.

Canadian officials say the country is shaping up for its worst wildfire season on record.

Environment Canada issued its strongest air quality warning for Ottawa on Tuesday, deeming it a "very high risk" to people's health.

Meanwhile, the US Environmental Protection Agency (EPA) classified the air quality in much of the north-east as "unhealthy" especially for people with respiratory concerns.

In New York, an orange haze blanketed the city's skyline and shrouded landmarks including the Statue of Liberty.

All outdoor activities at the city's public schools have been indefinitely suspended, with Mayor Eric Adams warning that conditions are expected to deteriorate later on Wednesday.

"We recommend all New Yorkers limit outdoor activity to the greatest extent possible," he said.

Local residents in the city said the smell of smoke by Tuesday evening was like a campfire.

On Wednesday morning, schools in the Washington DC area also cancelled outdoor activities as air quality levels were labelled "code red", while Detroit was listed as the fifth worst major metropolitan area in the world on IQAir's air pollution rankings.

Public health officials have cautioned people not to exercise outside and to minimise their exposure to the smoke as much as possible, as the air poses immediate and long-term health risks.

Matthew Adams, a professor at the University of Toronto and the director of its Centre of Urban Environments, said immediate effects of inhaling wildfire smoke include shortness of breath, an elevated pulse, chest pain, or inflammation in the eyes, nose and throat.

"On these elevated air pollution days, we'll see an increased number of visits to hospital," Prof Adams told the BBC. "And the people that are visiting the hospital typically have a pre-existing respiratory 

There were 160 wildfires burning across Quebec as of Tuesday,But wildfire smoke has also been linked to serious, long-term health issues like cancer or lung disease, Prof Adams said, specifically for people who live in areas that experience frequent forest fires.

This is caused by small particles in the smoke haze, he said, which can enter the bloodstream and other parts of the human body, causing possible DNA mutations and other health issues.

Some studies have also shown that prolonged wildfire smoke exposure can affect pregnant women and their unborn children, Prof Adams added.

For people living in cities far away from the fires but under current air advisories, Prof Adams advised people limit outdoor exercise to avoid breathing in the wildfire smoke.