OTTAWA - Hundreds of uncontrolled forest fires blazing across Canada are threatening critical infrastructure, forcing evacuations and sending a blanket of smoky air wafting over US cities.
Wildfires are common in Canada's western provinces, but this year flames have mushroomed rapidly in the country's east, making it the worst-ever start to the season.
About 3.8 million hectares (9.4 million acres) have already burned, some 15 times the 10-year average, said Federal Minister of Emergency Preparedness Bill Blair.
More than 20 000 people remained displaced across Canada as of Wednesday.
The giant eastern province of Quebec is among the worst affected. The province eagerly awaited the arrival of reinforcements from abroad to help beat back blazes that are overwhelming its firefighting capacity.
After major flare-ups in western Canada last month, firefighting efforts recently shifted to Nova Scotia on the Atlantic coast, before moving this week to Quebec, which is now the epicentre of the crisis.
"Across the country as of today, there are 414 wildfires burning, 239 of which are determined to be out of control," Blair told a briefing on Wednesday.
"We've ... seen continued impacts to critical infrastructure in Quebec such as roads and rural closures, telecommunication interruptions and high-voltage power lines being threatened by the growing fires," said Blair.
Quebec Premier Francois Legault said earlier the province was able to fight 40 fires at the same time.
"But we have 150 fires so we have to make sure that we focus where the problems are the more urgent," he told reporters.
In neighbouring Ontario province, Canada's most populous, deteriorating air quality has been forecast this week in cities including Ottawa and Toronto due to smoke plumes.
South of the border, more than a dozen US states were under air-quality alerts on Wednesday as smoke from the wildfires wafted south.
Schools across the US East Coast cancelled outdoor activities, airline traffic slowed and millions of Americans were urged to stay indoors on Wednesday.
The US National Weather Service issued air quality alerts for virtually the entire Atlantic seaboard. Health officials from Vermont to South Carolina and as far west as Ohio and Kansas warned residents that spending time outdoors could cause respiratory problems due to high levels of fine particulates in the atmosphere.
"It's critical that Americans experiencing dangerous air pollution, especially those with health conditions, listen to local authorities to protect themselves and their families," President Joe Biden said on Twitter.
US private forecasting service AccuWeather said thick haze and soot extending from high elevations to ground level marked the worst outbreak of wildfire smoke to blanket the north-eastern US in more than 20 years.
New York's famous skyline, usually visible for miles, appeared to vanish in an otherworldly veil of smoke, which some residents said made them feel unwell.
New York Governor Kathy Hochul called the situation an "emergency crisis", saying the air pollution index for parts of her state were eight times above normal.
In some areas, the air quality index (AQI), which measures major pollutants including particulate matter produced by fires, was well above 400, according to Airnow, which sets 100 as "unhealthy" and 300 as "hazardous".
Reduced visibility from the haze forced the Federal Aviation Administration to slow air traffic into the New York City area and Philadelphia from elsewhere on the East Coast and upper Midwest, with flight delays averaging about a half hour.
"We encourage everyone in the impacted areas to listen to their state and local conditions," White House spokeswoman Karine Jean-Pierre told reporters.
"Check in on your neighbours, check in on your friends and your family. Take precautions especially if you have health conditions."
She called the situation an "alarming example of the ways in which the climate crisis is disturbing our lives."
An unusually early and intense start to wildfire season has set Canada on track for its worst-ever year of fire destruction as warm and dry conditions are expected to persist for months.
"In coming years we will have to reflect seriously on how we can equip ourselves to deal with this new reality. We will be facing more and more extreme weather events that will cost us a lot more," Prime Minister Justin Trudeau told the briefing.
About 520 firefighters were battling the blazes with another 150 due to join soon from the army, Legault said.
He said he hoped 500 more firefighters would arrive in the next few days from the neighbouring province of New Brunswick as well as France, the US, Portugal, Spain, and Mexico.
Residents of the towns of Chibougamau and Ouje-Bougoumou in northern Quebec received evacuation orders on Tuesday night, becoming the latest group of people in the province to evacuate their homes after thousands were forced out last week.
About 11 400 people have been evacuated so far from remote parts of northern Quebec and another 4 000 will be evacuated soon, Legault said.
REUTERS and AFP