The air quality in New York has hit its worst point since at least the 1980s as smoke from Canadian wildfires continues to engulf the city.
On Wednesday the city’s air quality index rose to 353 out of 500, which is considered “very hazardous”.
Fox Forecast Center meteorologist Brian Mastro said the air quality was even worse than after the September 11 attacks but said the air was fortunately less toxic than the debris cloud from the terror attack.
By Thursday morning, the air quality index had fallen to 256, which is still considered to be “very unhealthy”.
At least 13 US states have air quality alerts issued in places, impacting an estimated 115 million people.
The US National Weather Service has issued air-quality alerts for virtually the entire Atlantic seaboard, while health officials in states from Vermont to South Carolina and as far west as Ohio and Kansas warned residents that spending time outdoors could cause health problems due to the number of fine particulates in the atmosphere.
In New York City, mayor Eric Adams urged residents to limit outdoor activity and told those with respiratory problems to stay indoors – advice echoed in Canada by prime minister Justin Trudeau as crews battled more than 400 wildfires, with the giant eastern province of Quebec among the worst-hit.
About 3.8 million hectares (9.4 million acres) have already burned, some 15 times the 10-year average, with Canada on track for its worst-ever year of fire destruction.
Why is this happening?
Smoke from Canada’s wildfires has been moving into the United States since last month. The most recent fires near Quebec have been burning for at least several days.
The big driver was prolonged hot, dry weather.
“The month of May was just off the charts – record warm in much of Canada,” said Eric James, a modelling expert with the Co-operative Institute for Research in Environmental Science at the University of Colorado who is also with the National Oceanic and Atmospheric Administration.
Those unusual conditions – the type that climate change is making worse – increased the risk of fires, he said.
The Quebec-area fires are big and relatively close, about 500 to 600 miles (roughly 800 to 970 kilometres) from Rhode Island and they followed wildfires in Nova Scotia.
Strong winds high up in the atmosphere can transport smoke long distances and it’s common for large, violent fires to create unhealthy conditions hundreds of miles away from where forests are burning.
The right mix of circumstances had to align for the smoke to blanket major US cities: A dry, hot spring set the stage for big fires. The weather did the rest, said Bob Henson, a meteorologist with Yale Climate Change Connections.
“It’s a simple matter of trajectory,” Mr Henson said. “The smoke goes where the wind takes it.”
In New York City, British actor Jodie Comer was forced to abandon a performance of one-woman Broadway play Prima Facie on Wednesday, reportedly complaining “I can’t breathe in this air” before being helped off stage. The show restarted with an understudy in the role.
The New York Yankees postponed their Major League Baseball game versus the Chicago White Sox, citing “poor air quality due to smoke from the Canadian wildfires” – while New York City’s zoos closed early “out of concern for our staff, visitors and animals”.
The Tribeca film festival, kicking off on Wednesday, said it would “monitor the situation closely” and may cancel outdoor red carpet events in the days ahead.
Some flights into the New York City area and Philadelphia were delayed and others briefly halted because of reduced visibility from the wildfire smoke from Canada.
Mayor Adams told a press conference there were “dangerously high levels” of wildfire smoke – with the air quality index in the city worse than the world’s most polluted megacities.
He added: “This is an unprecedented event in our city, and New Yorkers must take precautions. Vulnerable New Yorkers should stay inside, and other New Yorkers should limit outdoor activity. This is not the day to train for a marathon – stay inside, close windows and doors, and use air purifiers if you have them.”
He also suggested vulnerable New Yorkers should consider wearing face masks if they have to go outdoors.
Mr Adams warned that conditions would improve overnight but “are expected to deteriorate further” on Thursday, adding: “While this may be the first time we’ve experienced something like this on this magnitude, it is not the last.
“Climate change accelerated these conditions. These dangerous air quality conditions are clearly an urgent reminder that we must act now to protect our city, our environment and the future of our children.”
After the press conference, a Home Depot store in Manhattan sold out of air purifiers and masks as residents scrambled to protect themselves.
Some flights into the New York City area and Philadelphia on Wednesday were delayed and others briefly halted because of reduced visibility and Federal Aviation Administration traffic slowing measures.