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May 01, 2023

Canadian Wildfire Smoke Wrecks NY Air Quality: Live Updates

A hazy plume from Canadian wildfires delayed flights and prompted the

A hazy plume from Canadian wildfires delayed flights and prompted the cancellation of three big New York theater productions and two Major League Baseball games. Gov. Kathy Hochul of New York called the worsening air quality "an emergency crisis."

Liam Stack, Luis Ferré-Sadurní, Michael Paulson, Ed Shanahan and Emma Fitzsimmons

A plume of Canadian wildfire smoke rapidly darkened the skies of New York City and sent the air quality index soaring past 400 on Wednesday, well into the "hazardous" range and the worst since the Environmental Protection Agency began recording air-quality measurements in 1999.

By afternoon, Midtown Manhattan was plunged into a deep hazy orange and smoky clouds obscured visibility across the five boroughs and the region, canceling some flights. Earlier in the day, commuters donned masks used amid the Covid-19 pandemic while walking the streets, children stayed indoors at recess, some schools closed and officials warned people against going outside.

The smoke forced the cancellation of three big theater productions, "Hamilton," "Camelot" and a Free Shakespeare in the Park production of "Hamlet," as well as games hosted by the Yankees and the Liberty of the W.N.B.A.

Flight delays of one to two hours caused by low visibility continued into Wednesday night at La Guardia and Newark Liberty International Airports.

New York was not the only city in the state coping with dangerous breathing conditions. For much of Wednesday, the air-quality index in Syracuse topped 400, according to AirNow, which designates a reading above 100 as "unhealthy" to breathe and above 300 as "hazardous."

Speaking to reporters, Gov. Kathy Hochul called the worsening air quality in New York "an emergency crisis," warning that it could last several days: "People have to prepare for this over the long haul," she said.

The worst period of hazy, unhealthy air in New York City will last from Wednesday afternoon through Thursday morning, according to a New York Times analysis of computer forecast models. The haze will most likely vary in thickness through the overnight hours.

Here's what else to know:

Canada, where nearly 250 fires were burning out of control as of early Wednesday, was also in for more haze. Parts of Quebec and Ontario were under a smog warning, and experts warned that the air in Toronto and elsewhere was likely to worsen — probably on Thursday — before getting better.

Satellite imagery showed haze engulfing parts of the United States on Wednesday, and warnings were in effect across a wide portion of the Northeast and Midwest. Philadelphia was under a "code red," meaning sensitive groups could be at risk, and a Phillies baseball game was postponed.

The haze was expected to linger for a couple of days because the weather system pushing it around the atmosphere was relatively stagnant, the National Weather Service said in a forecast. Forecast models showed that a more dense smoke layer could reach further west into cities like Pittsburgh on Thursday.

The poor air quality could have widespread effects among healthy people and serious ones for those with respiratory conditions, according to federal guidelines. Such high readings are typical in smoggy megacities like Jakarta or New Delhi but rare in New York, where decades of state and federal laws have helped to reduce emissions.

Hilary Howard, Luis Ferré-Sadurní, Asmaa Elkeurti and Ed Shanahan contributed reporting.

Ed Shanahan

With another day of dangerously smoky skies expected in New York City on Thursday, it appeared that the city's activity calendar would be upended for a second straight day.

Flight delays of one to two hours caused by low visibility continued into Wednesday night at La Guardia and Newark Liberty International Airports.

GrowNYC, which operates the city's greenmarkets, said that all of its outdoor programming, its fresh food box, farmstand, garden and compost sites, would be closed on Thursday. The city also suspended alternate side of the street parking.

Here's how the smoke disrupted life in New York on Wednesday:

A game between the Yankees and Chicago White Sox was postponed and is to be made up as part of a doubleheader on Thursday, conditions permitting. A game between the Philadelphia Phillies and the visiting Detroit Tigers was also postponed.

A game between the Minnesota Lynx and the New York Liberty of the W.N.B.A. at Barclays Center in Brooklyn was postponed.

Wednesday night's performance of "Hamilton" was canceled after a number of performers called in sick. The Broadway revival of "Camelot" at Lincoln Center was also canceled.

The Public Theater canceled the final dress rehearsal of its free Shakespeare in the Park production of "Hamlet" Wednesday night and the first two scheduled previews of the play, on Thursday and Friday.

The nonprofit Off Broadway Vineyard Theater canceled a performance of the play "This Land Was Made."

A free concert by Taj Mahal and Corrine Bailey Rae in Prospect Park that was to kick off this summer's BRIC Celebrate Brooklyn season Wednesday night was canceled. Organizers said the show would not be rescheduled.

A live dance performance by the Bill T. Jones/Arnie Zane Company scheduled for Times Square was canceled.

The New York City parks department canceled or postponed all outdoor and indoor recreational events. The city's beaches were closed at 3 p.m.

The city's three public library systems closed early, at 3:30 p.m. The New York Public Library was planning a delayed opening on Thursday, at 11 a.m., but also planned to continue to monitor the air quality conditions. The Brooklyn and Queens library systems were set to open as usual.

The city's zoos also closed early, at 3 p.m., on Wednesday "out of concerns for our staff, visitors and animals," according to the Wildlife Conservation Society, which operates the zoos. Zoo officials were monitoring conditions to determine how to proceed on Thursday.

Michael Paulson

Jodie Comer, who left the stage 10 minutes into today's matinee of her one-woman Broadway play, "Prima Facie," because she was having trouble breathing amid New York's poor air quality, returned to the theater for tonight's performance, and has now begun the physically demanding show.

Jesse McKinley

In Buffalo, where the haze remains and tomorrow is expected to be smokier, a reflected image gives us a double sunset, Tatooine style.

Joseph Goldstein

New York City's public hospital system is reporting a minor increase in patients with respiratory ailments because of the smoke-filled air. "Some NYC Health + Hospitals’ emergency departments have seen an uptick in patients with smoke-related respiratory symptoms," a spokesman for the city's public hospital system, Christopher Miller, said Wednesday evening.

Ed Shanahan

Gov. Kathy Hochul announced that a million N95-style masks would be made available to the public, 400,000 of them in New York City, at state-owned sites including Grand Central Terminal, Penn Station, Fulton Center, Jamaica Station, Port Authority Bus Terminal, Denny Farrell Riverbank State Park in Harlem and Roberto Clemente State Park in the Bronx. The rest will be made available to local governments across the state, she said.

Ed Shanahan

GrowNYC, which operates New York City's greenmarkets, said that all of its outdoor programming would be closed on Thursday. In addition to the five greenmarkets that are typically open on Thursdays, the move affects the organization's fresh food box, farmstand, garden and compost sites.

Emily Cataneo

Charlotte, N.C., was still under a hazardous air alert as of Wednesday evening, with a haze lowering over the Bank of America Tower and other iconic Charlotte buildings. Clean Aire NC, a nonprofit based in Charlotte, warned residents by email to limit outdoor time and wear masks, and some day cares limited outdoor time for children. Nate Niezgorski, an Amazon Web Services employee and Charlotte resident who has asthma, said he drove with the windows down on Wednesday and spent time outside with his dog. When he went back inside his house, he had to grab his inhaler. "I noticed I was having difficulty breathing, which was kind of abnormal for me."

Emily Cataneo

Nancy Nicholson, a yoga teacher, said she didn't even notice the dip in air quality in Charlotte during her bike ride this morning. But others did. "It was definitely the talk of the class today," she said.

Kevin Williams

Residents of Middletown, Ohio, are used to black grit coating their cars from the belching smokestacks at the town's sprawling steel mill. But this week, Paula Cohen says that smoke from Canada's wildfires has taken misery to a new level.

"This stuff that is blowing in the air is just driving me crazy," said Ms. Cohen, 78. Typically, she would be outside enjoying her pool or garden on a nice June day, but the smoke chased her indoors.

About halfway between Cincinnati and Dayton in southwestern Ohio, Middletown on Wednesday was also near the western end of the hazy plume engulfing parts of the northeastern United States, with an air quality index of just under 150 for fine particulate matter. That's the border between what health officials designate as unhealthy for sensitive groups and bad for everyone.

Dr. Terri Moncrief, an allergist and immunologist at the Dayton Asthma and Allergy Center, said she has heard many complaints like Ms. Cohen's in recent days, with patient visits and phone calls spiking this week.

Ohio endured a very potent allergy season this spring, aggravated by dry weather, she said. Typically, early June brings relief. But not this year.

"I am worrying most about my asthma patients," Dr. Moncrief said. "They have noticed more difficulty breathing, and their chests are feeling tight. That is a big concern." She said some patients are coming into her office with their "eyes swollen shut."

"Even if you are not an allergic person, this smoke is irritating," she said.

Even Kevin Johnston, a member of the Ohio River Runners Club and volunteer firefighter who is used to smoke, found his eyes watering on his daily five-mile run. "Nobody is really complaining about their health," said Johnston, 60, "but they are asking about the haze."

Some of the thickest smoke plumes could drift west into parts of Ohio and western Pennsylvania later this week, forecasters warned, making things even worse. Matthew Campbell, a meteorologist in the Wilmington, Ohio, National Weather Service office, said relief won't arrive until the weekend, when wind patterns shift.

Sophie Downes

The line of people waiting to enter the Nederlander Theater for tonight's performance of "Shucked" appeared undaunted, but many of the theatergoers were wearing masks — now increasingly uncommon at Broadway shows.

Ashley Wu

Wildfire season has barely begun in Canada, and already fires have scorched more than 10.5 million acres across the country, according to the Canadian Forest Service. For comparison, the average area burned between May and early June each year over the last decade was nearly 680,000 acres.

2023

2014

10 million

acres

2015

2013

8

6

All other years

since 2012

4

2

July

Sept.

May

2014

2023

10 million acres

2015

2013

8

6

All other years

since 2012

4

2

July

Sept.

May

Note: Data is estimated from satellite-derived hotspots.

Source: Canadian Forest Service

By Ashley Wu

Michael Wilson

The smoke from wildfires hundreds of miles north that turned New York into a scene of unsettling gloom on Wednesday arrived as if from a burning building blocks away, draping the city in a thick and otherworldly orange-gray hue.

In the air hung the acrid smell of a campfire. Not fog, not mist, not really weather at all — this was something new to even veteran New Yorkers.

Automobile headlights flipped on midday, as drivers struggled to see. Streetlights lit automatically. Busy summertime sidewalks, their noontime shadows blurred out, gradually emptied. A woman leaving a grocery store stopped and pointed her phone's camera toward the blotted-out sky.

Mayor Eric Adams, at a news conference, gave voice to the way many New Yorkers likely felt when they stepped outside: "What the hell is this?"

City leaders urged caution, and to avoid the outdoors, and the reaction was swift. Yellow tape more familiar at crime scenes stretched across playground entrances. School recess yards remained vacant, and parents were urged to be prompt when picking up their children, to avoid keeping them waiting in the thick haze.

The daily bustle in Sunset Park's Chinatown in Brooklyn was absent on Wednesday. "No good," said Gigi Chen, selling live crabs — three for $25 — from a stand outside Blue Ocean Market. "Here, afternoons are busy," she said. "Not today." As she spoke, a man pushing a cart filled with clean and folded laundry hurried past, as if trying to outrun the odor.

The smoke and plunge in air quality resurrected scenes familiar from the pandemic lockdown in March 2020, and with them, a feeling of helplessness against forces out of our control. Masks returned to faces. Residents checked their screens for fresh data before venturing out — Covid infection rates then, AirNow.gov now.

The needle on the site's Air Quality Index gradually rose for New York City, from the category marked "Unhealthy" to "Very Unhealthy" to, finally, "Hazardous." Elsewhere in the state, the index was higher still.

Commuters flipped their pandemic precautions, wearing masks as they approached a subway station, and pulling them off before boarding. A small comfort: Smoke is not contagious.

And another, that this should pass relatively soon, with fresh air and the possibility of rain expected as the week continues.

But with the smoke still thick, unfamiliar sights were rife. Several of the popular courts at the Central Park Tennis Center sat empty after players canceled their reservations. Gray curtains of smoke lent a ghostly veil over Green-Wood Cemetery in Brooklyn.

On Broadway, the play "Prima Facie" was interrupted 10 minutes into the performance when its star, Jodie Comer, experienced difficulty breathing and was escorted offstage.

Outside in Times Square, the scene was more or less normal, with tourists coming and going — although everyone seemed to be talking about the same thing. Rishabh Mehta, 27, visiting the city with his wife and his parents from India, expressed disappointment at the turn of events.

"We cannot see the buildings if we go on top of the observatories," he said. "It's suffocating. We can't walk long distances. If we keep walking long distances, we get tired early."

Nearby, Rauf Rahimov, 27, a pedicab driver outside Central Park, reclined in the back of his cab where the passengers would sit, if there were any.

"No tourists, no people, no income," he said. He had made about $65 so far Wednesday, less than half of a normal day. In Brooklyn, a food deliveryman, Mohammad Uddin, said he was raised in Bangladesh, a country with a persistently unhealthy air quality. But he said nothing there compared to Wednesday in Brooklyn — "Oh, no, no, no, no, no."

Students gasped as they exited Fordham University's campus in Manhattan. An instructor said: "Smell that barbecue, man!"

In the Bronx, Jeremiah Ducille, 20, stood in slacks and a necktie next to a table advertising wireless phone service. He normally hates the hot sun and humid temperatures, and looked for comfort in the darkening sky above.

"Now that the smoke is out it's covering the sun," he said. "It's kind of better like this."

But on a bus traveling down Fifth Avenue in Manhattan, passengers could barely make out Central Park several feet outside the window. Gone was the queue of horse-drawn carriages outside a park entrance, another city ruling Wednesday.

"It's like the smoke got stuck, there's no breeze," said Dani Harkin, 54, on the bus. The eerie scenes outside her window reminded her of a very specific day.

"Last night, we didn't really realize, but it smelled — it smelled like 9/11," she said. "Like, ‘That's fire.’ It smelled like the day. I won't forget that smell."

Remy Hernandez, 40, a food deliveryman from the Bronx, saw the day through a similarly bleak lens. "To me, it looks like the world is ending," he said.

Uptown, a young child riding a scooter to school asked his father, "Why is it so foggy outside?"

Olivia Bensimon, Emma Fitzsimmons, Sean Piccoli and Michael D. Regan contributed reporting.

Jon Hurdle

Marcus Gaub, on a business trip to Philadelphia from his home in Germany, said he had never experienced such poor air quality, and fears it may become a more frequent occurrence because of climate change. "In the last years, there are more wildfires all over the world," said Mr. Gaub, 57, including in the forests of his home country. "It's too dry. In former times, that wouldn't have happened because of rain."

Megan Swift

Smoky air spread across much of Pennsylvania on Wednesday, with the forecast calling for conditions to worsen on Thursday. Skies over the sprawling Penn State University campus in State College, at the center of the state, took on a grayish-orange hue as the federal air quality index hit 200, considered "very unhealthy."

Air quality across Central PA is very poor this evening as smoke from Canadian wildfires continues to impact the region. More information about air quality can be found at https://t.co/nIkI6nGgYF. pic.twitter.com/2uFBxrUSzK

Eduardo Medina

Rhode Island officials issued an air quality alert for Thursday, saying that the "significant smoke event will unfortunately continue," bringing "wood-burning odors, haze and unhealthy fine particles readings throughout the day." Like millions of other residents across the northeast, Rhode Islanders were advised by the department of environmental management to stay indoors and wear an N95 mask outside.

Michael Paulson

As smoke from Canadian wildfires blanketed New York City and seeped into theaters, alarming both ticket holders and performers, the Broadway productions of "Hamilton" and "Camelot," as well as a Free Shakespeare in the Park production of "Hamlet," canceled performances.

"Hamilton" announced at 6:45 p.m. that it was canceling its 8 p.m. performance Wednesday night because so many cast members had called in sick.

"Tonight's performance of Hamilton will not go on as scheduled," Shane Marshall Brown, a spokesman for the production, said in a statement. "The hazardous air quality in New York City has made it impossible for a number of our artists to perform this evening."

At about the same time, Lincoln Center Theater announced that its Broadway revival of "Camelot" was also canceling a Wednesday night performance; spokeswoman Juliana Hannett cited "the impact of the air quality on our artists."

"Shucked," a new musical, planned a concert-style performance of its show, featuring composer Brandy Clark, after several actors called out sick for reasons that a spokesman said were unrelated to air quality.

The Public Theater canceled the final dress rehearsal for "Hamlet" on Wednesday night, and said the loss of rehearsal time plus ongoing concern about air quality was prompting it to cancel the first two scheduled previews of the play, on Thursday and Friday nights.

Broadway's theater owners and producers held an emergency meeting Wednesday afternoon to discuss the impact of declining air quality, but, mindful that many patrons and performers were already in place for the evening's shows, decided to let any shows that could continue with their performances that night. There were 31 performances originally scheduled to take place at Broadway theaters on Wednesday night; because of upgrades made in response to the coronavirus pandemic, the theaters have air filtration systems that are supposed to be able to reduce pollutants.

"Broadway remains open this evening and most shows are set to perform," the Broadway League's president, Charlotte St. Martin, said in a statement.

The decision came as air quality levels in New York reached record levels of unhealthiness, and as many organizations, including the New York Yankees, were canceling events — initially mostly outdoors, but then, as the haze lingered, indoors, too.

The smoke has been affecting live performances in New York for more than 24 hours. On Tuesday night, the Public Theater cut short a technical rehearsal of "Hamlet," citing air quality concerns, and then on Wednesday morning Little Island, a small park built on the Hudson River, canceled its art-making activities.

Broadway felt its first major impact shortly after 2 p.m., when the actress Jodie Comer stopped her acclaimed (and physically demanding) one-woman show, "Prima Facie," just 10 minutes after it began, saying she was having trouble breathing. The show restarted with her understudy, and Comer returned for the Wednesday evening performance.

There were several other scrapped performances as government officials began talking more loudly about the health risks of going out. Vineyard Theater canceled a performance of its new play, "This Land Was Made." New York Live Arts canceled a dance performance in Times Square by Bill T. Jones/Arnie Zane Company. And BRIC, a Brooklyn-based arts organization, canceled the opening night of its Celebrate Brooklyn festival, which was to include a concert headlined by Taj Mahal and Corinne Bailey Rae.

Eduardo Medina

Officials in Delaware have declared a Code Red Action Day, indicating that the air quality will remain unhealthy across the state through Thursday and that residents should stay indoors as much as possible. The department of natural resources and environmental control cautioned that young children, older adults and those with lung problems "could be more significantly impacted" as the code red remains in effect.

Michael Paulson

The Public Theater canceled the first two previews of "Hamlet," this summer's Free Shakespeare in the Park production, which had been scheduled to take place Thursday and Friday in the open-air Delacorte Theater in Central Park. The nonprofit had cut short its final technical rehearsal on Tuesday and canceled an invitation-only dress rehearsal on Wednesday night, citing air quality, and said those rehearsal cancellations on top of the air quality concerns prompted the decision to delay the start of the "Hamlet" run.

Emma Fitzsimmons

Mayor Eric Adams of New York just held his second smoke-related news conference of the day, urging New Yorkers to stay indoors and warning that the air quality index had hit a hazardous level at 484. The smoke is expected to temporarily improve late Wednesday and on Thursday morning, the mayor said, but should deteriorate again on Thursday afternoon.

Emma Fitzsimmons

Mayor Eric Adams of New York said on Wednesday evening that the city was canceling outdoor events, and he encouraged other organizations to cancel outdoor events on Wednesday night and on Thursday. His health commissioner said that there was no evidence yet of an influx of patients with respiratory or cardiovascular issues at city hospitals.

Emma Fitzsimmons

Mayor Eric Adams of New York City stopped short of calling for most New Yorkers to work from home on Thursday to avoid the smoke emergency. Asked if private employers should encourage people to work remotely, Adams said that New Yorkers should use "proper discretion" and that employers should allow people with pre-existing conditions to work from home. "Unless people must come out, the best thing to do at this time is to remain indoors," he said.

Eduardo Medina

In Syracuse, N.Y., the air-quality index topped 400 for much of Wednesday, a level considered hazardous to breathe, prompting the Syracuse Mets to postpone its Wednesday night game and to cancel its Education Day for children at the ballpark. The city's school district said that while air quality could improve tomorrow, all outdoor activities would still be canceled on Thursday.

Recent reports relating to the air quality in CNY indicate that tomorrow (6/8) we should see an improvement in air quality. Out of an abundance of caution, we are still going to cancel all outdoor activities incl. sports, recess, field trips, after school & evening activities. pic.twitter.com/1ljXpfKeDm

Sarah Maslin Nir

As the air quality in New York City climbed to the worst on record, people who make their living outdoors faced a hard decision: focusing on their health, or their jobs.

Mohammad Uddin, a food delivery worker, was making do the best he could in Bedford-Stuyvesant, Brooklyn, as he drove his electric scooter though the yellow haze. His visor was up, and he had a length of printed cloth tucked under his bike helmet that covered his mouth. He was considering cutting short his typical nine-hour shift, as he drove through thick air that stung his eyes and throat, but not until he had earned at least $100.

Then his phone rang. "My wife is calling," Mr. Uddin, 30, said. "She said, ‘You can come back.’"

All across the city outdoor workers were getting a similar call on Wednesday. The New York City Parks Department closed all city beaches, and parks maintenance staff were given the option to work indoors today.

The Worker's Justice Project, which advocates for delivery workers, advised drivers to stay home, though many cannot afford to, Ligia Guallpa, the executive director, said in a statement. "Numerous delivery workers on duty are directly experiencing the effects of this air pollution, including shortness of breath and other adverse health effects," she wrote. "It is not the first time they have been at the front lines, ensuring the safety of New Yorkers by allowing them to stay indoors."

Sitting on top of his black and red scooter in front of the Bronx County Hall of Justice, Remy Hernandez, 40, an Uber and DoorDash delivery driver, said orders had dropped considerably since the smoke rolled in on Tuesday.

"People are scared to come out in this smoke," Mr. Hernandez said. "To me it looks like the world is ending."

Grubhub advised delivery workers with pre-existing conditions to stay inside, according to Liza Dee, a spokeswoman. Drivers would not be penalized if they believed a delivery was unsafe to complete.

Neither Uber nor the Department of Transportation responded to repeated inquiries about precautions they were taking for employees regarding the air quality.

Selling Yankees T-shirts and hats from her table on Grand Concourse Boulevard in the Bronx, Trina Elliott, 20, a Washington Heights resident, said that she was asthmatic but had not yet had an episode.

"I have my inhaler," she said. "I’ve just been praying," she added.

At his newsstand outside the 161st Street subway station nearby, Ahmed Babu, 49, said the smoke had slowed business, but not him. Originally from Dhaka, Bangladesh, where air quality is regularly unhealthy, he said he was used to pollution. "It's not too bad here," Mr. Babu said.

Con-Ed, the power company, limited outdoor work for all but the most essential jobs, according to Karl-Erik Stromsta, a spokesman.

Even nonhuman employees were off the job: The 200 horses who pull Manhattan's 68 carriages were ordered back to their stalls by the New York City Health Department, along with all equines employed in the several barns across the five boroughs.

With the competition from the horse carriages in Central Park gone, pedicab drivers waited idly for tourists without luck. They appeared to have fled for the safety of indoors.

Rauf Rahimov, 27, was sprawled in the back of his pedicab, waiting for customers as the haze enveloped the treetops above. By the afternoon, he had made only about half of what he usually draws in a day. "No tourists, no people, no income," he said.

From the vantage point of his halal food cart near the Bronx County Civil Court building, Mohamed Sharf, 50, a Manhattan resident, thought the fear of the smoke was overblown.

"Some people are acting like the zombies are coming," he said. "New Yorkers don't care."

Olivia Bensimon, Sean Piccoli and Michael D. Regan contributed reporting.

Emily Cataneo

Raleigh, N.C., got some rain during rush hour on Wednesday, while clouds and a barely perceptible haze hovered over downtown. The air quality alert had been downgraded to a Code Orange, and residents were going about their business downtown on Wednesday evening, running, delivering pizza on bikes, walking dogs and texting under the shelter of umbrellas. Some schools in Wake County, which includes Raleigh, and surrounding towns moved outdoor activities indoors during the day.

Troy Closson

The attendance rate for New York City's public school students was just over 84 percent on Wednesday, according to new data from the Education Department, only a slight drop from about 87 percent on Tuesday, even as some families and teachers worried over the air pollution.

Hilary Howard

The apocalyptic skies, hazardous air and stinging eyes of the last two days may soon be regular occurrences for New Yorkers because wildfires are on the rise, said Daniel Westervelt, a professor at Columbia University's Lamont-Doherty Earth Observatory.

"Anecdotally, we’ve seen a few of these," Dr. Westervelt, who is also an air pollution adviser to the State Department, said. He noted that smoke from West Coast wildfires engulfed New York City in 2021, creating conditions that he described as similarly "unhealthy."

According to a 2021 report published by the journal GeoHealth, despite most large wildfires occurring in the western United States, most deaths, emergency room visits and hospital admissions in America that are attributable to smoke occur elsewhere, particularly in the East.

Katelyn O’Dell, an author of the report and a researcher at George Washington University, said there are more people in the East, which is why more smoke-related health issues occur there, and that wind patterns, which bring dangerous air conditions from the ever-increasing number of fires in the West to the East, also play a role.

"It's really important to monitor air quality before embarking on outdoor activities," Dr. O’Dell said, citing resources like AirNow.gov. One's nose and eyes are not always good indicators, she added.

The link between traveling smoke and climate change, via the increase in wildfires, is real, Dr. Westervelt said. Extreme heat, caused by carbon emissions, means drier conditions, which affect soil moisture, he said. "That fuel on the ground, like leaves and sticks, is more susceptible to sparks," he explained.

When there is less precipitation than normal, warmer temperatures cause vegetation to dry out more quickly, said Ethan Coffel, a climatologist at Syracuse University.

All of that means more fires. Earlier this week, Canada had over 400 active wildfires, while New Jersey, which is still recovering from its most recent major wildfire (one that covers more than 100 acres) and which has had over 14,000 acres burn this year, is now getting pummeled from the smoke traveling from the north.

Not every wildfire produces air emergencies far away, Dr. Westervelt said — that depends on meteorology. He attributed the current situation along the East Coast to an air mass, or low-pressure system, in upper New England that is creating the perfect conditions for wind to bring the smoke down the East Coast.

The good news is that air masses are always in motion, Dr. Westervelt said. When they change direction, so will the smoke. It could also rain, he said, which is nature's way of clearing the air.

Andy Newman

The air quality index in New York City, which peaked at 413 around 4 p.m., has dropped slightly to 364, though it is still classified as "hazardous," according to airnow.gov

Asmaa Elkeurti

The concentration of pollutants in the air around New York City hit the highest levels ever recorded on Wednesday afternoon, more than doubling the previous record set the day before.

As smoke from hundreds of Canadian wildfires continued to billow south over the region, the air quality index hit 413, darkening the skies and prompting many New Yorkers to remain indoors.

Established by the Environmental Protection Agency to measure air pollution around the United States, the air quality index tops out at 500. An index number above 100 typically triggers health warnings for children, older people and other vulnerable groups. A number above 300 is considered hazardous to everyone.

Before Wednesday afternoon, the highest air quality index figure ever registered in the New York City region was recorded on Tuesday, when it hit 174. The next highest was recorded more than 20 years earlier, on July 7, 2002, when the index hit 167 thanks to smoke from another rash of Canadian wildfires.

The air quality index, a measure of pollutants in the air, was more than twice as high on Wednesday as any measurement previously recorded.

Note: Record-keeping begins in 1999

Source: U.S. Environmental Protection Agency

By Asmaa Elkeurti

The E.P.A. has been recording air-quality index figures since 1999. The number in New York on Wednesday was driven upward by high concentrations of fine-grain particulate matter from the wildfires, the agency said.

New York City's air quality has generally improved in recent years, federal data shows, with the number of days when the air quality index number was above 100 declining each year.

George Thurston, an air pollution researcher at New York University's Grossman School of Medicine, said that although the air outside might have looked alarming, it was not as hazardous as the fossil fuel pollution that the index was created to measure.

He said the federal legal standards for air quality were based on particles from those emissions, which tend to contain toxic metals and chemicals like sulfur and sulfuric acid. Such contaminants are not typically found in wildfire smoke, Professor Thurston said.

"You have to be careful comparing these numbers for a forest fire with the ambient standards, which is what the air quality index is doing," he said.

Dani Blum

An air purifier, like one that uses a HEPA filter, is the best way to improve the quality of your indoor air — but if you are staying inside to avoid wildfire smoke and don't have access to an air filter, there are a few other things you can do to keep the air in your home as clean as possible.

The next best tool after an air purifier is an air-conditioner, said Dr. Panagis Galiatsatos, a pulmonary and critical care medicine physician at Johns Hopkins Medicine. Keep your windows closed, and make sure your air-conditioner is set to recirculate air, said Dr. Samantha Green, a family physician at Unity Health Toronto. You may want to replace the air filter in your central air-conditioner. Wirecutter, a New York Times company, has guidance on the air filters and purifiers that can help protect against wildfire smoke, and a tutorial on how to create a D.I.Y. air purifier.

If you don't have air-conditioning, portable fans and ceiling fans can help. Keep fans close to where you are inside — and if you happen to have multiple fans, turn on all of them. "Anything that can help circulate the air is better than nothing," Dr. Galiatsatos said.

You should keep bathroom exhaust fans off as much as possible if they bring in outdoor air, Dr. Green said. Some range hoods over kitchen stoves also allow outside air to infiltrate your home (if you’re cooking, you should use the range hood but try to limit the amount of time it's on).

To further minimize the pollutants in the air, don't burn candles or light a fire, and refrain from frying meat. Smoking indoors is always a bad idea, Dr. Galiatsatos said, but particularly when you’re already susceptible to exposure from wildfire smoke. "Now is the time to promote lung health," he said.

Richard Fausset

Atlanta was one of the many places across the eastern U.S. on Wednesday where the sky remained a light, bright blue, with big cotton clouds and perhaps the slightest tinge of haze. But the National Weather Service warned of potentially unhealthier conditions in the hours to come. The air quality index had risen to 108 by 4 p.m., according to a federal air-quality monitoring website, a level deemed unhealthy for sensitive groups. But it was expected to drop to a less troublesome "moderate" level on Thursday.

Reduced air quality is possible today and tonight due to smoke from Canadian fires🔥. Particularly sensitive groups may be affected in North GA. Visit https://t.co/N4vGvi8AJF to check current air quality conditions.Expect hazy conditions with red sunrise/sunsets🌅.#gawx pic.twitter.com/jMK6pdYEdQ

Luis Ferré Sadurní

Gov. Hochul said the haze was forecast to drift more heavily into the western parts of the state next: "Buffalo and West New York are going to be in trouble tomorrow. This plume is moving."

Jesse McKinley

The governor said the air quality in Buffalo right now: 155

Luis Ferré Sadurní

She said state officials expected the situation "to abate possibly over the weekend," but cautioned that the movement of the smoke remained fluid and subject to wind patterns and other factors.

Jesse McKinley

New York itself had a surprising round of wildfires last year, with several significant blazes in the Hudson Valley.

Jesse McKinley

Gov. Hochul in Albany right now: "Please don't go out if you don't have to."

Luis Ferré Sadurní

Gov. Kathy Hochul of New York said the state will make available one million N-95 masks from a state stockpile. The masks will be distributed in subway stations, state parks and directly to local governments.

Dani Blum

Breathing in wildfire smoke can cause a headache right away, according to the Centers for Disease Control and Prevention, and short-term exposure to particulate matter from wildfires has been linked to an increase in emergency room visits for headaches.

Researchers are not entirely sure why wildfire smoke causes headaches, but one reason may be that it can alter the sensitivity of certain neurons, which in turn can increase the risk of headaches, said Dr. Raj Fadadu, a researcher at the University of California, San Francisco School of Medicine who has studied the health effects of wildfire smoke.

Wildfire smoke can lead to lower oxygen levels if you have an underlying lung condition like asthma, which can contribute to a headache, said Dr. Panagis Galiatsatos, a pulmonary and critical care medicine physician at Johns Hopkins Medicine. Inhaling wildfire smoke can also lead to inflammation, which can itself induce headaches.

If you are outside in an area with poor air quality and you feel a headache coming on, that's most likely a sign you should head indoors, said Dr. Fadadu. To ward off headaches — and any other effect from smoke — restrict the amount of time you spend outdoors, he said, and try to optimize the quality of your indoor air. If you have access to an air purifier, like one with a HEPA filter, that can help. You should also steer clear of smoking or vaping.

If you do need to go outside, consider wearing a tightfitting mask, like an N95. While wearing a mask indoors is not typically recommended to reduce smoke exposure, if you believe you are encountering poor air quality, putting on a mask may lower your risk of inhaling polluted air, and therefore could help address headache symptoms, Dr. Fadadu said.

The most effective treatment for headaches can vary from person to person, but over-the-counter medications like Tylenol or Advil can help. Staying hydrated is also critical, Dr. Fadadu said. If you can, try to avoid looking at screens while your headache persists; at the least, consider reducing the brightness of your screen, which can ease the strain on your eyes. If your headache is not responding to treatments at home, or is becoming more intense, you may want to go to an urgent care center or emergency department, he added. A physician may prescribe stronger medications to better manage the pain.

If you have underlying pulmonary issues and you are experiencing a headache after exposure to wildfire smoke, consider testing your oxygen levels and contacting your doctor, Dr. Galiatsatos said.

There's another possible reason for your wildfire-smoke headache: stress. A growing body of research shows that environmental disturbances take a toll on mental health, and stress can contribute to tension headaches, which are mild, throbbing headaches typically felt on both sides of the head.

The anxiety that people may feel looking at the orange-tinged haze, or assessing whether to put on a mask before leaving their homes, might itself contribute to headaches — particularly on the East Coast, where people are not used to grappling with the tangible impact of wildfire smoke, Dr. Fadadu said.

"That ecological stress that we’re seeing with wildfires is, for sure, a real phenomenon that a lot of people are experiencing," Dr. Fadadu said.

Jesse McKinley

Schools in Western New York are canceling after-school activities, though the air is largely clear in downtown Buffalo.

Jennie Coughlin

The view from the Manhattan Bridge is hazier than it was at 6:30 a.m., but visibility has improved since early afternoon.

Dana Rubinstein

Citing poor air quality, New York City has suspended alternate side parking for Thursday.

Michael Paulson

Vineyard Theater, an Off Broadway nonprofit in the Union Square neighborhood of Manhattan, has canceled tonight's performance of the play "This Land Was Made," citing "hazardous air quality conditions."

Benjamin Hoffman and Tyler Kepner

With air quality in the Bronx registering at "hazardous" levels because of smoke from wildfires in Canada, Major League Baseball postponed a game between the Yankees and the Chicago White Sox, which had been scheduled for 7:05 p.m. on Wednesday at Yankee Stadium.

The game is scheduled to be made up on Thursday as the first game of a single-admission doubleheader, the Yankees said. That could change if the air quality continues to be unhealthy. Manager Aaron Boone said he had been told that conditions were expected to improve, but "obviously we’ll get here and see."

A game between the Phillies and the Detroit Tigers in Philadelphia was also postponed on Wednesday, as was a W.N.B.A. game between the Minnesota Lynx and the Liberty in Brooklyn.

The decision to postpone the M.L.B. games — made at the league level with input from the teams, the players’ union and weather experts — came at 4:30 p.m. Eastern, with the air quality in the Bronx registering at 413 on the Environmental Protection Agency's Air Quality Index, according to AirNow. Philadelphia's A.Q.I. was at 233.

The Yankees and the White Sox played a night game on Tuesday when the A.Q.I. was higher than 150 at the first pitch and higher than 200 shortly after the game ended. (Anything from 101 to 150 is classified as unhealthy for sensitive groups. From 151 to 200 is unhealthy, 201 to 300 is very unhealthy, and anything over 301 is hazardous.)

"One thing we did right away was we canceled batting practice — we were going to do our stuff inside," Boone said. "I don't know why I wanted to walk outside, but I just walked out, and you see the orange coming through the doors and you’re like, ‘Whoa!’"

Carlos Rodón is pitching at Yankee Stadium right now. He's throwing a live session against hitters like Jake Bauers and Oswaldo Cabrera. pic.twitter.com/w4kc94WwET

Despite Boone's decision to cancel batting practice on Wednesday, several players worked out on the field at Yankee Stadium, including Carlos Rodón, a starting pitcher trying to work his way back from the injured list.

"I was just focused on throwing the ball over the plate, really," Rodón said of his workout. "I didn't think about the breathing part. But it's thick air, that's for sure. I can't imagine it would be easy to see fly balls."

Other M.L.B. games in the Northeast were not postponed on Wednesday because the conditions in those cities were not as severe. The Pirates played an afternoon game against the Oakland Athletics in Pittsburgh with an A.Q.I. in excess of 150 at various points. The Guardians were expected to play their night game against the Boston Red Sox in Cleveland with the A.Q.I. at around 100.

While there were numerous complaints from journalists and fans on social media about the decision to play the full schedule of games on Tuesday, players and coaches for the Yankees played down the difficulty. Third baseman Josh Donaldson said that it had seemed foggy but that it had been "nothing out of the ordinary," and Boone compared it to the smog that teams are used to playing through in Southern California.

One White Sox player said he had felt some adverse affects after Tuesday's game.

"You know, I had a cough this morning, sore chest — nothing too terrible," Andrew Vaughn told reporters on Wednesday. "Some of those balls went up and you kind of lose them for a second. It got a little hazy, and you kind of lose them in the lights. It was definitely tough to see."

A situation similar to this week's events played out on the West Coast in 2020. The Oakland Athletics and the Seattle Mariners played a September doubleheader that season with an A.Q.I. of 220 at the first pitch, also as a result of wildfires, only for M.L.B. to relocate the Mariners’ next two games to San Francisco after criticism from players and fans.

Asmaa Elkeurti

New York City's Air Quality Index has just reached a "hazardous" 413, according to data from AirNow.

Benjamin Hoffman

A game between the Minnesota Lynx and New York Liberty has been postponed because of air quality issues that were affecting conditions at Barclays Center in Brooklyn, according to the W.N.B.A.

Benjamin Hoffman

Major League Baseball has postponed two of Wednesday night's games because of poor air quality. The Yankees were expected to play the Chicago White Sox in the Bronx, and the Philadelphia Phillies were expected to play the Detroit Tigers in Philadelphia, but both will now be rescheduled.

Troy Closson

New York City's public schools were previously scheduled to be closed for children on Thursday, taking one major issue off the plate of city officials. Still, tens of thousands of teachers and staff were set to attend a professional development workshop, and officials have not yet decided whether it will become virtual.

On Wednesday afternoon, the chair of the City Council's education committee and a group of educators within the city's teachers union both called for all in-person programming to be canceled.

In light of the recent public health advisories from both State and City agencies; I am calling for @NYCSchools staff to be permitted to work remotely tomorrow, especially since students will have off due to Brooklyn Queens Day.

Here is MORE's response to the Air Quality Advisory & Chancellor's Day tomorrow:As this statement is written, the New York State Department of Environmental Conservation has extended the Air Quality Health Advisory for New York State to June 8th, & Air Quality is considered 1/7

Campbell Robertson

Even as the haze hung heavy in the blue-white sky over the nation's capital on Wednesday afternoon, the weekly market carried on in Woodrow Wilson Plaza, just north of the National Mall.

The booths had been open since the morning, and the after-lunch crowd filtered through, looking over produce, crepes, popcorn and jewelry, seemingly unconcerned by the unusual sky above.

Across the Washington, D.C., area, though, schools had been taking steps to limit students’ exposure, as the air quality deteriorated to Code Red levels. Public schools in the District, and some of the Maryland and Virginia suburbs, canceled all outdoor activities.

At the market in Wilson Plaza, two vendors, Sunah Blu and Milton McCarl, chatted over the tables of body butter and herbal soap, talking about the air around them.

"It looks like a heavy fog, but a dirty fog," Ms. Blu, 46, said.

They both agreed: It seemed part of a pattern of odd phenomena recently. The weather was strange over the weekend, getting colder and then hotter suddenly. At the Eastern Market on Capitol Hill, where they set up shop on Saturdays, a couple of fights broke out, which was unusual, they said. There was the sonic boom on Sunday. And now this.

"It feels like something broke in the atmosphere," Mr. McCarl said.

Lauren McCarthy

In a news conference, Gov. Kathy Hochul encouraged New Yorkers to stay indoors if they can. She said the state saw an 800 percent increase in worsening air conditions over the past 24 hours, reaching hazardous conditions. "The bottom line is this: If you can stay indoors, stay indoors. This is detrimental to people's health," she said, adding, "You may not see it, you may not even feel it, but it is having a negative effect on everyone."

Judson Jones

The worst period of hazy, unhealthy air in New York City will last from Wednesday afternoon through Thursday morning, according to a New York Times analysis of computer forecast models. The haze will most likely vary in thickness through the overnight hours and could last through the day Thursday.

The Washington, D.C., region can expect dense smoke to arrive Wednesday night and last into the day Thursday.

Forecast models for smoke near the surface show that from Thursday night into Friday, the main swath of dense smoke could move further west, into western Pennsylvania and Ohio.

Places like Toronto may get a burst of more dense smoke early Thursday as the storm system pushes the smoke further west and before it crosses the Great Lakes into the United States. In Toronto and other places, haze and smoke density may vary and change hour to hour through Friday, with possible improvements this weekend.

However, the further into the future you go, the less confident forecasters are in predicting the effects and density of the smoke.

That is partly because the high-resolution computer models get refreshed once an hour and are distributed a little less than a day in advance. Also, the models can't predict how much smoke the wildfires will produce over the next several days.

This has been a perfect weather scenario to create extremely unhealthy air. A persistent blocking pattern has locked the weather in place, leaving a storm system hovering near Nova Scotia and pushing strong northerly winds over the Canadian wildfires.

Strong wind has kept the smoke together and nearer to the surface as it pushed into the United States. If there had been calmer winds, the smoke would have risen and dispersed more in the atmosphere, making it less concentrated.

The weather pattern may finally break down this weekend, and by Sunday the winds may shift, providing relief from the smoke. Relief could come even earlier if progress is made on putting out the wildfires.

Don't hold your breath, though; experts say this is only the start of wildfire season in North America.

Ian Austen

Speaking with reporters, Prime Minister Justin Trudeau of Canada said on Wednesday that his government is looking into the possibility of creating a federal disaster response organization.

"We continue to discuss and look at new mechanisms and new ways of doing that," he said.

"We need to continue to make sure we are doing everything possible to both keep Canadians safe when these extreme weather events hit, but also make sure we’re doing everything we can to predict, protect and act ahead of more of these events coming."

Sean Piccoli

Outside a popular soul food restaurant in Bedford-Stuyvesant, Mohammad Uddin, a food delivery worker, said he had started his shift around 1 p.m. He would normally work until 10 p.m., but with a greenish haze settling overhead, Mr. Uddin said he would not work past 6 p.m. A native of Bangladesh who said he has lived in Brooklyn for five years, Mr. Uddin estimated that he would earn about $100 for the day — a figure he described as middling.

Jeff Mays

All three of New York City's library systems closed their doors at 3:30 pm today, a few hours earlier than normal, because of deteriorating air quality conditions, according to spokeswomen for the agencies. The three systems have hundreds of combined locations and normally stay open until at least 6 p.m. on weekdays. Many unhoused people spend time at the city's libraries during the day.

Michael Paulson

The actress Jodie Comer, who has been nominated for a Tony Award for her tour-de-force performance in the one-woman show "Prima Facie," stopped a performance on Broadway shortly after it had begun on Wednesday afternoon, citing difficulty breathing because of the wildfire smoke that has blanketed New York City.

"Today's matinee of ‘Prima Facie’ was halted approximately 10 minutes into the performance after Jodie Comer had difficulty breathing due to the poor air quality in New York City because of smoke from the Canadian wildfires," Jim Byk, a spokesman for the production, said in a statement.

The performance then restarted with an understudy, Dani Arlington.

Ms. Comer, known for her work on the TV show "Killing Eve," is a leading contender to win the Tony for best actress in a play during the awards ceremony on Sunday. In "Prima Facie" she plays a defense lawyer whose clients have included men accused of sexual assault, but who then is sexually assaulted herself and begins to see the legal system in a different way.

Sharon Otterman

The New York City Air Quality Index has reached 392, even higher than the record set earlier today, according to the AirNow Index.

Judson Jones

Visibility — measured in miles in the United States — indicates how far a person can see and is most commonly used during dense fog and blizzards. Today it is being used to measure how far people can see in the dense smoke layer. In New York, visibility has at times been reduced to around a mile making the city's skyscrapers seem to disappear.

Check out this almost unbelievable time-lapse of wildfire smoke consuming the World Trade Center and the New York City skyline.Those vulnerable to poor air quality, including seniors and young children, should limit time outdoors if possible.More: https://t.co/ChRuWv7X6E pic.twitter.com/mtKtLun8lN

Olivia Bensimon

Rauf Rahimov, 27, a pedicab driver in Central Park, heard on the news that the polluted air would last for days but that did not deter him from coming to work. "We’re doing outdoor businesses, most of our income comes from the tourists. No tourists, no people, no income," he said while laying on the back of his cab waiting for tourists to call on him for a ride.

Tracey Tully

A blaze that spread overnight to 70 acres in central New Jersey now has a name: Glory Wildfire.

By Wednesday, the fire was about 70 percent contained, a technical term used to define the portion of a blaze surrounded by a so-called fuel break, which limits its risk of spreading, according to the state's Forest Fire Service.

But residents of Jackson, N.J., where the wildfire was still threatening 15 homes and businesses, were urged to take precautions as airborne particulate levels climbed to levels considered unhealthy for the second day in a row.

The cause of the wildfire remains under investigation, a spokeswoman for the Department of Environmental Protection said.

Wildfires are relatively common in New Jersey. So far this year, 819 wildfires have burned more than 14,500 acres, according to the environmental protection agency.

In April, one large blaze, Jimmy's Wildfire, burned nearly 4,000 acres in Manchester Township, southeast of Jackson.

The number of fires that have burned during the first five months of the year is significantly higher than the state experienced in either 2022 or 2021.

Last year, 539 wildfires burned 740 acres between January and early June, state officials said. In 2021, 650 wildfires burned 1,800 acres during the same period of time.

"Make no mistake, from the wildfires in Canada to those cropping up with increasing frequency and severity in our own backyard, these extreme weather events are tangible — and devastating — evidence of the intensifying climate crisis," New Jersey's governor, Philip D. Murphy, a Democrat, said in a statement.

WILDFIRE UPDATE: Glory Wildfire - East Commodore Blvd. - Jackson Twp, Ocean County@njdepforestfire made substantial progress overnight in containing a wildland-urban interface wildfire burning in Jackson Twp.The wildfire has grown to 70 acres in size and is now 70% contained. pic.twitter.com/zQJafI86eg

On Wednesday, the air quality near Jackson had slipped into the red "unhealthy" zone, according to AirNow, which tracks particle pollution nationwide.

Conditions were not much better throughout the rest of New Jersey as smoke from wildfires raging in Canada blanketed much of the region.

Residents were advised to limit their time outdoors Wednesday and Thursday, particularly those with heart or lung disease.

"A little bit of caution isn't necessarily bad coming on the heels of the pandemic," said Dr. Eric Costanzo, director of pulmonary critical care at Hackensack Meridien Jersey Shore University Medical Center.

Inhaled particulate matter can cause an "inflammatory cascade," he said, leading airways to constrict. This, in turn, can cause coughing, wheezing and shortness of breath, he said.

"It's reasonable to be adhering to the warnings," he added.

The Port Authority of New York and New Jersey took the unusual step of closing several of its container terminals at 3 p.m. on Wednesday. "Due to wildfires there is poor visibility," the Port Authority wrote on Twitter. "Please drive with care."

And in a practice that has become more common on the West Coast, where recent studies show summertime air quality has been degraded by wildfires, many schools in New Jersey postponed sports activities and outdoor celebrations scheduled for Wednesday.

One of the practices canceled was in Bergen County, in northern New Jersey. High school seniors preparing for next weekend's all-star football game were told early Wednesday that their 4 p.m. practice had been called off as the state braced for the air quality to get even worse by late afternoon and evening.

For Dennis Hard, who has been coaching football for 43 years, it was a first.

"This is really weird," said Mr. Hard, who is retiring and expects next Saturday's all-star game to be his last. "I can't blame them for being careful."

Gregg Vigliotti

Orchard Beach in the Bronx, which is often filled with people from throughout the city, was all but empty Wednesday, as smoke from wildfires in Canada inundated the city.

Jesus Jiménez

As air quality worsened across the Northeast on Wednesday and officials urged people to stay inside as much as possible, zoos brought their residents indoors — prioritizing some animals over others.

At the Toronto Zoo, Grant Furniss, the zoo's director of wildlife care, said that workers were eyeing the air quality levels and using that information to decide which animals needed to be brought indoors.

Mr. Furniss said that animals with previous respiratory illnesses were among the first to be brought inside. Those animals are put in buildings with ventilation systems, and extra fans are set up "to try and get any of the smallest smoke particles moving in and out of those buildings as quickly as possible."

"We really do treat them as if they were human beings," Mr. Furniss said.

Birds are also at the top of the list, because they are more susceptible than other animals to poor air quality, Mr. Furniss said.

Many of the rest of the animals, he said, are free to roam between the indoor and outdoor portions of their habitats.

"But if we do see any distress in any of those animals, we bring them in immediately," Mr. Furniss said.

Despite high levels of air pollution in Toronto as smoke spreads from wildfires in Canada, Mr. Furniss said that the Toronto Zoo had been "pretty busy" on Tuesday and Wednesday, with hundreds of visitors and school groups. Workers were given N95 respirator masks if they needed to be outside, the zoo said.

In upstate New York, zoos in Syracuse and Rochester, where air quality was also at "unhealthy" levels, closed.

The Seneca Park Zoo in Rochester said in a statement that zoo staff were monitoring the air quality and that "select species" could be brought indoors if it worsens.

Zoos in the New York City area opened on Wednesday, but closed early at 3 p.m. The Wildlife Conservation Society, which oversees the city's zoos, said that the zoos closed "out of concern for our staff, visitors and animals."

Carriage horse rides in New York City were suspended on Wednesday because of the air quality, according to Shari Logan, a Health Department spokeswoman.

Mr. Furniss said that in general, wild animals are resilient and find ways to adjust to their environments.

"It's very much a scenario of being adaptable and being able to adapt to the situation," he said.

Dana Rubinstein contributed reporting.