News

Aug 17, 2023

Canada Wildfires Worsen Air Quality for Millions in North America: Live Updates

Air pollution warnings were in effect across Canada and the United States,

Air pollution warnings were in effect across Canada and the United States, including New York City, where residents were advised to limit outdoor activity on Wednesday.

Mike Ives

Millions of people across North America on Wednesday faced another day of hazy skies and serious air pollution caused by smoke that had drifted down from Canadian wildfires a day earlier.

Hundreds of wildfires have been burning in eastern Canada for weeks. On Tuesday, eye-watering smoke from the fires drifted south and cast a pall over parts of the U.S. Northeast and Midwest. The grayish haze had hints of orange, yellow or purple, depending on where you stood. One New York City commuter described the smell as progressing during the day from "burnt toast" to "campfire."

The air in New York on Wednesday was clearer than the day before, but the air quality was expected to deteriorate during the day, forecasters said. Although the city's schools were open, they were not holding outdoor activities, Mayor Eric Adams announced. The city and much of New York State were under an air quality health advisory alert — indicating that the index was expected to surpass 100 — that was in effect until Wednesday night.

On Tuesday night in Manhattan, the Air Quality Index hit 218, indicating that it was very unhealthy and was likely to produce widespread effects among healthy people and serious ones for those with respiratory conditions, according to federal guidelines. Such a reading is typical in a smoggy, traffic-choked megacity like Jakarta or New Delhi but rare in New York City, where decades of state and federal laws have helped to reduce emissions.

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.

Warnings were in effect early Wednesday across a wide portion of the Northeast and Midwest. Philadelphia was under a "code red," which could put sensitive groups at risk. 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.

Victor Mather

On an evening when the sky was filled with an eerie haze, the smell of smoke lingered and the air quality index hit unhealthy levels, baseball went on as usual at Yankee Stadium in the Bronx.

The Yankees faced off against the Chicago White Sox, starting at 7:05 p.m. on Tuesday, and while players and coaches said they were not bothered by the smokiness, the smell was certainly present, making it an unusual experience for fans and players alike.

"I didn't really think much about it other than that it looked odd out there," Yankees Manager Aaron Boone said after Chicago's 3-2 victory.

Smoke from wildfires in Canada drifted into numerous parts of the northern United States on Tuesday, and New York City had some of the worst conditions. By 10 p.m., around 30 minutes after the game ended, the air quality in the city rose to 218 on the Environmental Protection Agency's Air Quality Index. A score above 200 is considered "very unhealthy." At the time of the first pitch, the index was around 150, the cutoff for "unhealthy."

Mayor Eric Adams recommended limiting outdoor activities when possible and urged people with heart or breathing problems to stay indoors.

Air quality postponement decisions are made by Major League Baseball, in conjunction with the players’ union, not the teams involved. M.L.B. did not immediately respond to a request for comment. The Yankees and the White Sox are scheduled to play again on Wednesday night at 7:05 in the Bronx.

In September 2020, the Oakland Athletics and the Seattle Mariners played a doubleheader in Seattle despite smoke from wildfires on the West Coast and a "very unhealthy" air quality rating of 220 at the first pitch of the day. Two games the next day, between the Mariners and the Giants, were postponed and moved to San Francisco.

At least one player on Tuesday night got a laugh out of the situation. "The air wasn't thick enough," Yankees pitcher Clarke Schmidt, who gave up a home run to Seby Zavala, told The New York Post. "The homer down the line might not have gone out."

Kevin Yamamura

Some New Yorkers were out running this morning under orange skies, and all I could think was, why didn't they check their air quality apps?

Wildfire smoke has changed our way of life in California each summer and fall. Forget hours or even days of smoke. We have lived through weeks and months of hazy air, stretches where you forget what blue skies even look like.

In Sacramento, where I live, the air quality can change quickly depending on which way the wind is blowing, especially the Delta breeze — the wind coming off the Sacramento and San Joaquin Rivers — from the coast.

Sometimes the winds push smoke into our valley. Other times, particulates get sent the other way to the Bay Area, forcing residents there to live in a blanket of haze.

Californians have their favorite air quality websites and apps. Those run by the E.P.A. and local air boards are the gold standard, but crowdsourced sites like Purple Air are also helpful.

We have become well-versed in the color-coding schemes that are tied to the air quality index for particulate matter. As with traffic lights, green and yellow mean we are usually fine to exercise. Orange makes you think twice.

But red is usually a no-go, an indicator that the A.Q.I. is above 150. Purple or maroon? Don't even consider it.

The worst recent years here coincided with my training for cross-country races or a fall marathon.

My Sacramento Running Association team of competitive runners was wise enough to recognize we needed to save our lungs but obsessive enough to know we needed to get our miles in. One teammate who works at the California Air Resources Board would regularly chime in with time-of-day forecasts based on wind patterns and conditions.

Unlike the Northeast today, our region sometimes had pockets of relatively clean air within driving distance. After days of living with this, we would become desperate enough to check the map and head for a run in a nearby neighborhood with an orange or yellow rating.

We have great outdoor options, so many of us hate treadmills (or "dreadmills," as we call them). But some would break down and get gym memberships. Even that is not foolproof — we learned quickly that not all gyms have great ventilation systems.

The first whiff of smoke often sends California residents scurrying to replace their HVAC filters with the highest-rated ones they can find; if you’re too late, you’ll find the shelves bare of all but the weakest options. (Head to the hardware store now!)

When the smoke arrives, we alter our outdoor activities based on the rhythms of the wind. We keep our windows closed. Some become "air tourists," desperately seeking relief by staying with friends and family in locations with clean skies.

And we constantly refresh our air quality apps and websites, hoping for a green light.

Jenna Russell

In western Massachusetts, emergency department visits for respiratory illnesses ticked up this week at Pittsfield's 300-bed Berkshire Medical Center, a spokesman said. An air quality advisory issued by the state's Department of Environmental Protection, in effect through midnight Wednesday, urged people with asthma or heart or lung disease to avoid prolonged outdoor exertion, and to keep medications close at hand for quick relief. Smoke was forecast to spread slowly eastward toward the coast.

Ana Ley

Some commuters this morning were wearing heavy-duty masks on their walk to the subway in Brooklyn, where the air has been smoky and thick, then removing them once they packed into trains.

Troy Closson

New York City's schools chancellor, David Banks, was asked about reports that some public schools still have field trips or outdoor lunches planned, even as all outdoor activities for students are supposed to be canceled. "There are no trips that should be planned," Banks reiterated.

"I don't know if there's a specific principal or teacher that wasn't aware," he said. "But the system at large has been fully notified."

Luis Ferré Sadurní

Gov. Kathy Hochul of New York urged school districts statewide to cancel outdoor activities. "According to the most recent forecast, much of the state outside of the North Country is expected to be in an air quality index of unhealthy to very unhealthy today," she said.

Judson Jones

The "sun is no longer visible, everything's orange, the parking lot lights have come on," forecasters from the National Weather Service office in Binghamton tweeted Wednesday morning. The swath of more dense smoke will continue to move south over the next several hours and visibility is expected to decline as it does.

9:45 AM at NWS Binghamton. Sun is no longer visible, everything's orange, the parking lot lights have come on, and we're stuck at 50°F. pic.twitter.com/Ibu2oE2af5

Dana Rubinstein

Mayor Eric Adams on Wednesday pushed back against complaints that the city did not communicate quickly enough with New Yorkers about the dangerous air quality. "Let's not create a controversy where there is none," the mayor said.

Chris Stanford

You’ll be hearing a lot about the Air Quality Index today. A measure of pollution, the index runs from 0 to 500, with higher numbers indicating unhealthier air. We answered other common questions about the index here.

Chris Stanford

You can find air quality data for where you live here.

Claire Moses

Yes, it's Global Running Day. No, you probably shouldn't go for a run today.

The New York Road Runners canceled all its Global Running Day-related events on Wednesday as smoke from wildfires in Canada drifted over large parts of the United States. "If you’re in NYC or any affected area, please read and follow your city's health advisory regarding air quality for June 7, and consider running another day."

On Tuesday, the running club had already urged people not to go for a run outside, and to log their outdoor miles after the skies had cleared. This is especially true for people who suffer from chronic respiratory conditions like asthma.

A 2021 study by the European Heart Journal concluded as much, saying that an increase in exercise in a highly polluted environment "may adversely affect cardiovascular health."

"People should avoid exercising outdoors during smoky conditions," California's Air Resources Board advises. "Exposure and the resulting health effects depend on the amount of time spent outside, level of exertion, level of air pollution, and possible existing health conditions."

Smoke from wildfires includes a mix of particles. Some — like dust or smoke — are big enough to be seen with the naked eye. Others, however, are microscopic, about one-fifth to one-30th as wide as a human hair. Those tiny ones can travel deep into a person's lungs and bloodstream. For runners, smoky conditions can also hinder visibility.

During exercise, people largely breathe through their mouths instead of their noses. The mouth — unlike the nose — doesn't have a natural filtration system for pollutants, which means more pollutants can enter the body, according to the American Lung Association. And the ultrafine particles aren't exhaled during exercise.

"If you’re a New Yorker with heart or breathing issues, be careful when you’re outdoors," New York City's mayor's office advised. "Try to limit outdoor activities today to the absolute necessities."

On Tuesday, New York's air quality rating briefly ranked as the worst of any city in the world, according to the IQAir World Air Quality Index.

For competitive athletes, there may be another reason to postpone an outdoor run: Polluted areas may also cause you to run slower, a 2019 study found.

If the conditions last, several days’ worth of polluted air could have a cumulative effect, Australia's Sports Commission said, "lowering an athlete's threshold for symptoms."

Dana Rubinstein

The air quality in New York City is the worst it has been since the 1960s, according to New York City health commissioner Ashwin Vasan.

Dana Rubinstein

Mayor Eric Adams of New York City urged vulnerable residents to stay inside this morning and warned that the conditions would likely stretch over several days. "This is not the day to train for a marathon," he said.

Jon Hurdle

Rocky Balboa's view from the Philadelphia Art Museum steps would be hazy this morning if he ignored advice from health officials and went for his famous training run. "If you must go outside," the city's Health Department said, "avoid excessive activity, such as jogging or running, and wear a mask, if available."

Emily Cataneo

The sun struggled to break through the clouds and a light haze this morning in Raleigh, N.C., over Hillsborough Street, a main thoroughfare on North Carolina State University's campus. With temperatures 10 degrees cooler than yesterday and a persistent wind, it felt like the calm before a storm.

Emily Cataneo

To the west, Charlotte, N.C., and the surrounding region were forecast to see their worst air quality since November 2016, when a fire from South Mountains State Park about an hour to the northwest spread smoke to the city.

Troy Closson

In New York City, the smoke had a disappointing consequence for some schoolchildren: The cancellation of long-awaited field trips that are common in the final weeks of the year. For most schools, Friday is the last day for a field trip — which means that for some, rescheduling plans might not be an option.

Jon Hurdle

After 10 minutes walking to work through the haze in Philadelphia, Jamie Gallagher, who has asthma, put on a Covid mask for the rest of the 35-minute trek. "I wasn't fully wheezy, but I wasn't able to take as deep an inhale as I normally do," said Gallagher, a 32-year-old musician. "So I thought it would be better to be safe than sorry."

Jon Hurdle

Skyscrapers in downtown Philadelphia were obscured by haze early Wednesday. The air quality index was in the unhealthy range, and the city health department recommended that residents try to avoid going outside, or wear a mask if they needed to. State officials warned that much of Pennsylvania would see similar poor air quality.

Emma Fitzsimmons

Update from Manhattan this morning. Less hazy than last night, but not great! My kindergartener is bummed he has to wear a mask on his field trip. (He thought his mask wearing days were over.)

Campbell Robertson

Citing air quality concerns, public schools in Washington, D.C., announced that all outdoor activities — including recess, outdoor P.E. classes, sports practices or field trips — would be canceled on Wednesday.

Claire Moses

Today's the day to put that mask back on.

As smoke from wildfires in Canada drifts over large parts of the United States, the best thing to do to prevent breathing in pollutants on Wednesday is to stay indoors. For many people, of course, that's impossible. So if you do have to brave the outdoors, putting on a mask is the next best thing.

But beware, not all masks work equally well. A surgical mask, scarf or bandanna won't do much to keep you from breathing in pollutants.

N95 masks can filter tiny particles that are less than 0.3 micrometers. By comparison, the width of a single human hair is approximately 60 micrometers, according to California's health department.

Instead, use N95 face masks (you may still have some of those left from the pandemic), or respirator masks, which you can find in hardware stores or online. Make sure to cover both your nose and mouth.

"Air quality is at unhealthy levels in New York today due to wildfire smoke drifting down from Canada," Lucky Tran, a scientist, wrote on Twitter. "Reminder that N95 masks help protect against smoke too. It's a good idea to wear a mask outside today!" He also advised people to turn on indoor purifiers.

People in areas affected should take the smoke seriously, experts warned. "Wear N95 or better masks and stay inside if you can, with air purifiers," Mask Oakland, a project that responds to smoke in the Bay Area-based community organization, advised.

Sarah Garland

Many New Yorkers who were headed to work or school on Wednesday pulled out their Covid masks to wear outdoors as a haze continued to hang over the city.

Campbell Robertson

The haze was steadily wafting into the Mid-Atlantic, with Baltimore and Washington waking up to air-quality alerts. The air carried the faint scent of smoke.

Campbell Robertson

The National Weather Service cautioned people to avoid exercising outside, and TV weather anchors suggested commuters take a few more minutes to drive, given lower visibility.

Sean Plambeck

The sunrise over Brooklyn this morning was once again obscured by hazy skies, though the sun appeared less red than it had the day before. Joggers and dog walkers were out in McCarren Park, with only a few wearing face masks to help with the poor air quality.

Molly Peterson

Thick smoke can sneak into your home through loose seals and cracks; closing those up can help. Simply shutting windows can cut pollution by about 30 percent. If it still smells like a barbecue inside on a smoky day, placing wet towels around cracks under doors and around windows can slow smoke's entry into your home.

The E.P.A. also recommends avoiding activities like cooking, vacuuming or smoking on smoky days, which can stir up pollutants already inside your home. And the American Lung Association recommends using a good welcome mat to wipe your shoes on, or taking shoes off altogether when you’re walking around inside your house, to avoid tracking in contaminants.

If your indoor space is larger than an air purifier can filter, the E.P.A. recommends dedicating one room as a "clean room" to use as a refuge on smokier days. But avoid using rooms where you create smoke or other particles indoors, like the kitchen, or any room with a lot of windows and doors.

Judson Jones

Smoky skies are possible through Friday as the current weather pattern pushes the wildfire smoke south. The intensity of the smoke will vary.

Judson Jones

Forecasters with the National Weather Service in Buffalo warn that today's plume of smoke in their region could make the sky even more opaque than it was on Monday, when the sun was barely visible at times because of how thick and low to the ground the smoke was.

Judson Jones

Haze and smoke will continue today, with another significant push of thick wildfire smoke likely across the Northeast, according to forecast weather models. The more intense plume of smoke is expected to hit major cities like New York later today and into tonight.

Jennie Coughlin

The skies above Times Square are hazy with wildfire smoke on Wednesday morning.

Mike Ives, Jin Yu Young and Muktita Suhartono

The dangerous haze hovering over parts of the Northeast and Midwest on Wednesday morning was highly unusual for the United States. For many people around the world, it would be somewhat normal.

Cities across Asia, Africa and Latin America have been so polluted for so long that air-quality readings like the ones expected across parts of New York State on Wednesday — which is expected to pose risks for people with respiratory problems — would not be seen as particular cause for alarm.

"Maybe foreigners can feel it, but for me it's just the normal air I breathe every day," Paiboon Kaewklangrong, a taxi driver in Bangkok, said on Wednesday. "Polluted, hot, dusty. But it is what it is."

In a prepandemic study, the World Health Organization found that 99 percent of the world's population lived in places that did not meet its guidelines for healthy air quality.

Bad air can be dangerous, especially if you’re breathing it over a lifetime. Short-term effects include coughing, congestion and inflammation. Longer-term exposure can damage your liver and brain, and increase the risk of blood clots that can cause heart attacks.

An added risk with smoke from wildfires is that the particulate matter they produce, known as PM, can mix with emissions from cars, factories and stoves in urban areas, said Rajasekhar Balasubramanian, an air quality expert at the National University of Singapore.

"It is therefore reasonable to assume that the PM in smoke haze is more toxic than the usual urban PM," he said.

The W.H.O. estimates that the effects of outdoor and household air pollution are associated with about 6.7 million annual deaths worldwide, mostly in low- and middle-income countries.

South Asia has nine of the world's 10 cities with the worst air, and "persistently hazardous" pollution that causes an estimated two million premature deaths a year, the World Bank said in a recent report. That pollution is partly a function of emissions from vehicles and heavy industry, but also from brick kilns, burning fields and other sources. People from poor families, who spend more of their lives outdoors and can't afford air filters, tend to face the greatest risks.

In East Asia, years of chronic air pollution is one reason that wearing face masks was common well before the coronavirus pandemic. School children there are used to playing inside on bad air days. In the Korean language, bad air has a specific term — fine dust — and its levels are displayed in real time in places like train stations, bus stops and elevators.

"I know fine dust is a problem, and I don't think twice about it anymore," said Lee Hyung-ko, a university student from Seoul, the South Korean capital. "It's not going away soon, so we just have to live with it."

Air pollution can also weigh heavily on politics. In South Korea, would-be presidents have made reducing air pollution part of their campaign platforms. In China, smog over Beijing and other cities has been seen over the years as a failure of leadership. And smoke that occasionally wafts from forest and peatland fires in Indonesia to other parts of Southeast Asia tends to infuriate neighboring governments.

Sometimes political pressure over bad air leads to tangible changes. Starting in the late 1980s, as Mexico City came under international criticism for its bad air, the city and nearby state government undertook a series of measures, such as limiting how many days cars could circulate each week and shutting an urban refinery. The reforms mostly worked: The city's air improved dramatically.

In other cases, urban air has improved because of something that no one saw coming. In Bangkok, as in New Delhi and other cities, for example, the air in the city of 11 million people improved noticeably during the coronavirus pandemic, said Mr. Paiboon, the taxi driver, who has been driving a cab for 18 years.

Now it's back to normal.

"If you drive early morning up on the tollway, you can see it's all hazy," he said. "It looks like fog, but it's not. It's all dust particles."

Steve Kenny

Even in the dark, as New Yorkers wait to see what color the sky will be at dawn, it is impossible to escape the smoke. A 50-block subway ride from Midtown to the Upper West Side, which takes about 15 minutes, ends with a sore throat and stinging eyes. You can't escape the smell, and clothes go right in the washer.

Eduardo Medina

Complaints of dry eyes, coughing and hoarseness. Patients calling their doctors to describe their difficulty breathing. Parents asking if their asthmatic children should attend school in-person.

Across New York City, doctors fielded questions and health problems from residents confronting dangerous smoke originating from Canadian wildfires and drifting through city streets on Tuesday, casting the sky in a pale hazy hue and prompting calls to medical providers.

A wave of New York City residents sensitive to smoke and feeling symptoms caused by the poor air quality were contacting health professionals on Tuesday night as the pollutants hovered above, according to Dr. Ramon Tallaj, the chairman of SOMOS Community Care, a network of health care providers in the city that treats more than 1 million patients in lower-income neighborhoods.

"We have to sound the alarm," Dr. Tallaj said, "because all these symptoms are going to happen."

New York City had the worst air quality of any major city in the world at one point on Tuesday night, according to a live ranking by IQAir, a technology company that tracks air quality and pollution around the world. Historically, New York City does not rank in the top 3,000 cities with the worst air quality, according to IQAir.

Dr. Tallaj said that many doctors have been busy all day answering calls from patients experiencing symptoms like coughing and loss of breathe, and wondering what to do.

In an interview, Dr. Tallaj said that his voice sounded hoarse because he has respiratory problems and was already suffering from the smoke, too.

Some people have had to go to urgent care because they were having difficulty breathing, he said.

"A lot of particles are in the air," he said. "It's going to get into your body through your skin, through your eyes and through your respiratory tract. It's going to cause you irritation."

Dr. Denise Nuñez, a pediatrician in the Bronx who is a part of the SOMOS network, said that most of the patients she saw on Tuesday at the urgent care center and at her clinic were for lung-related irritations, especially from people with asthma.

Most patients have been advised by doctors to stay home and to put on a mask if they have to go outside.

Nathaniel Styer, a spokesman for New York City Public Schools, said education officials were "making schools aware of the air quality health advisory," recommending that outdoor activity be limited and asking that "special attention be made to vulnerable students and staff populations."

Mayor Eric Adams said on Twitter that New Yorkers with heart or breathing issues should limit their time outside to "to the absolute necessities." Gov. Kathy Hochul urged residents in a statement "to take appropriate steps to help limit risk of exposure."

Dr. Tallaj said doctors have been reiterating the same message: "This is not the time to be in the street."

Dan Bilefsky and Vjosa Isai

More than 400 active wildfires were burning across Canada on Wednesday, according to the authorities, exacerbating a wildfire season that has forced the evacuation of tens of thousands of people, created a sense of anxiety across the sprawling country and triggered air quality alerts hundreds of miles south in the United States.

The danger of wildfires, which over the past few weeks have stretched from British Columbia on the west coast to Nova Scotia, nearly 2,900 miles away in the east, was brought home on Tuesday to the political heart of the nation. A thick haze hovered over Parliament Hill and the soaring Gothic Revival building that houses Canada's Parliament in Ottawa. The sun was obscured by smoke, the sky an apocalyptic orange hue.

Prime Minister Justin Trudeau of Canada said that hundreds of soldiers were deployed across the country to help with firefighting efforts. "This is a scary time for a lot of people," Mr. Trudeau said early this week, noting that many Canadians who had to evacuate in recent days had just a few hours to pack before fleeing their homes.

Bill Blair, the emergency preparedness minister, told reporters last week that over the month of May an area of roughly 2.7 million hectares, or about 6.7 million acres, of forest in British Columbia, Alberta, Manitoba, Saskatchewan, Nova Scotia, New Brunswick, Ontario and the Northwest Territories had been scorched. "The equivalent of over 5 million football fields has burned in Canada so far this year," he wrote on Twitter.

In a country known for its picturesque landscapes and orderliness, the out-of-control wildfires have stoked unease and underlined the perils of global warming. Scientific research suggests that heat and drought associated with climate change are major reasons for the increase in bigger and more intense fires buffeting the country.

The fires have also underscored the interconnectedness between Canada and its neighbor to the south with smoke from the hundreds of wildfires blazing in eastern Canada casting a hazy pall over New York City and polluting air quality from Minnesota to Massachusetts.

In eastern Canadian cities like Toronto, Montreal and Ottawa, where the majority of the country's people live, which had thus far been largely immune from wildfires in far away provinces, Tuesday ended any sense of complacency. Ottawa was among the places in Ontario with the highest health risk from its poor air quality, according to local authorities.

Palls of smoke also hung over Toronto, the country's financial capital, on Tuesday night and schools announced that students would be spending recess on Wednesday inside. During the day, an acrid smell filled parts of the city as many residents avoided going outside.

"With wildfire smoke in the forecast for Toronto, is it time to bring back masks?" asked The Toronto Star, evoking bad memories of pandemic times.

With more than 160 active wildfires in Quebec on Tuesday, some residents in Montreal were shutting their windows. A smog hung over parts of the city, and health authorities advised residents in Laval, a city north of Montreal, to wear N95 masks.

The wildfires were also hurting businesses, with many mining companies suspending operations in Quebec.

Katrina Eyk, a senior meteorologist at Environment and Climate Change Canada, the ministry that coordinates environment policy, said that winds had been pushing plumes of wildfire smoke from Quebec across southern Ontario, undermining air quality and visibility. Canadian health authorities have warned the smoke can cause symptoms ranging from sore and watery eyes to coughing, dizziness, chest pains and heart palpitations.

"It's still pretty yucky out there," Ms. Eyk said from Toronto on Tuesday evening. "But on Thursday, it looks like with the wind overall shifting to the northeast, that plume could move directly overtop of the Greater Toronto Area and give pretty poor conditions."

The wildfires have already shaken British Columbia and Alberta, an oil and gas producing province, where residents of its largest city Calgary have sat down for breakfast in recent weeks as pungent smoke leaked in from cracks under their front doors.

On the east coast of Canada, in Halifax, Nova Scotia, a wildfire late last month forced the evacuation of more than 16,000 people.

Michael Mehta, an environmental social scientist and professor at Thompson Rivers University in Kamloops, British Columbia, said that the visceral reality of smoke hovering over major cities could foster renewed debate on the risks of climate change.

Until now, he said, many on the east coast had not been exposed, firsthand, to the health risks of air pollution caused by wildfires that have gripped the western provinces over recent years. "There's essentially a disconnect," he said. "They haven't had this experience."

Ed Shanahan

Mayor Eric Adams said in a news release late Tuesday that by 10 p.m. air quality in parts of New York City had become "very unhealthy," rising to 218 on the Environmental Protection Agency's Air Quality Index.

New York's air quality rating briefly ranked as the worst of any city in the world on Tuesday, according to the IQAir World Air Quality Index. By comparison, the city's air quality has generally been below 50 on the index in recent years, in the "good category," and even improved during the pandemic-driven lockdown in 2020, according to IQAir.

"While conditions are anticipated to temporarily improve later tonight through tomorrow morning, they are expected to deteriorate further tomorrow afternoon and evening," Mr. Adams warned. He noted that the state's Department of Environmental Conservation had issued a citywide air-quality health advisory.

The mayor indicated that the city's schools would be open on Wednesday and he urged all students to attend, but he added that schools would not be holding outdoor activities. About 10 Public Schools Athletic League soccer, baseball and softball games had been scheduled for Wednesday.

"We recommend all New Yorkers limit outdoor activity to the greatest extent possible," Mr. Adams said. "Those with pre-existing respiratory problems, like heart or breathing problems, as well as children and older adults, may be especially sensitive and should stay indoors at this time."

The mayor said he would brief the public on his administration's plans Wednesday morning.

Ed Shanahan

In a message posted on Twitter late Tuesday, Nathaniel Styer, a spokesman for New York City Public Schools, said education officials were "making schools aware of the air quality health advisory," "recommending that outdoor activity be limited" and asking that "special attention be made to vulnerable students and staff populations." It was not clear whether Public Schools Athletic League games scheduled for Wednesday would be postponed.

Jon Hurdle

Looking out from the 18th floor of a skyscraper in downtown Philadelphia on Tuesday afternoon, Megan Harper noticed that the city looked different. The light, filtered through a fog of smoke particles, cast the buildings in a "shimmery purple."

The city felt different, too. The poor air quality kept her "sneezing like a maniac" on her walk home.

Wildfires raging in eastern Canada have sent smoke drifting south, shrouding areas of the United States — like Philadelphia — largely unaccustomed to the effects of the conflagrations that tend to consume landscapes in the West. The hazy skies that draped Philadelphia reminded Ms. Harper, she said, of a visit to Colorado, where the air had been polluted by fires in Montana.

Carolyn Moneymaker, a software engineer who works in Center City Philadelphia, used to live in Colorado. During wildfires there, she said, the smoke would obscure the sun much as it did in Philadelphia on Tuesday.

"You would get this very distinct look where the sun is clearly shining but something is in front of it," Ms. Moneymaker, who now lives in suburban Malvern, Pa. "You can see something is blocking it out."

When she was out walking on Monday, Ms. Moneymaker noticed a grayish tinge to the sky. By Tuesday, she could hardly see other buildings from the window of her 27th floor of her workplace.

Maddy Wescott, a product manager for a technology company, said she noticed the poor air quality when she went outside her office building on Monday.

"I sat outside on the patio, and I could not stop coughing," said Ms. Wescott, 28, who lives in the Fairmount section of Philadelphia. "I almost went back in."

Tracey Tully

In Jackson, N.J., residents were coping with more than just poor air quality from Canadian wildfires. New Jersey's Forest Fire Service was struggling to contain a wildfire that was covering about 30 acres Tuesday evening near East Commodore Boulevard and Cedar Swamp Road in Jackson, a 60,000-resident community in Ocean County. Several roadswere closed and 30 structures were at risk of being consumed by fire, state officials said.

Scott Dodd

As wildfire smoke fills the skies with gray haze, it can also turn the sun (or moon) a bright red. I asked Kofi Donnelly, who teaches physics at a Brooklyn high school, to explain why. White light from the sun is made up of all colors in the spectrum, he said. But smoke particles in the air "tend to scatter the shorter wavelengths (bluish light) more than the longer wavelengths (reddish light). Therefore bluish light from the sun is scattered in a bunch of directions (not into your eyes), while reddish light still gets to your eyes."

Jesus Jimenez

That's a wrap in the Bronx, where the Yankees lost 3-2 against the Chicago White Sox. The announced attendance was 38,049 fans, who watched a two-hour and 28-minute ballgame on a night when officials were recommending limiting time outdoors. Several other minor league baseball games in the Northeast also went on tonight despite air quality alerts.

Molly Peterson

By some estimates, a good air filtration system can cut smoke pollution indoors by about 50 to 80 percent. When skies grow hazy, if you have central air and heating, close your windows and switch your system's filtration settings to recirculate.

Adding a higher efficiency filter, like one with at least a Minimum Efficiency Reporting Value (MERV) 13 rating, to central air systems makes them even more effective at removing small particles from smoke. If you don't have central air, portable air purifiers with HEPA filters can work well in smaller spaces.

Experts caution that you should avoid using air purifiers that rely on and emit ozone, which can be harmful even at low levels and can irritate the lungs. Check with your local public agencies to see if they provide guidance or financial support for buying air filters. Low-income people with certain respiratory conditions who live in the Bay Area, for instance, are eligible for free portable air filters.

If you can't find an affordable air purifier, you can make one out of a box fan, some tape and some high efficiency filters.

Jesus Jimenez

Bryan Ramsey, a National Weather Service meteorologist in New York, said that the New York City area could see some smoke clear by Wednesday morning, but that it was possible another thick plume of smoke could move into the region by Wednesday afternoon, much like the one New Yorkers saw on Tuesday. "It's going to be here for a while," Mr. Ramsey said of the smoke.

Jesus Jimenez

New York City has the worst air quality of any major city in the world right now, according to a live ranking by IQAir, a technology company that tracks air quality and pollution around the world. Historically, New York City does not rank in the top 3,000 cities with the worst air quality, according to IQAir.

Ben Shpigel

The New York Road Runners, the organization that owns and stages the New York City Marathon, urged runners living in areas polluted by the smoke to consider not running on Global Running Day on Wednesday. Jennifer Stowell, a postdoctoral fellow at Boston University's School of Public Health, who has studied the health effects of wildfires, told The Times in 2020 that wildfire smoke "may be more toxic" to the lungs than standard urban air pollution.

June 7 is Global Running Day, but if you're in NYC or any affected area, please read and follow your city's health advisory regarding air quality, and consider running another day. pic.twitter.com/YPYfgr284b

Molly Peterson

If a wildfire is close enough that you can see flames or if your community is blanketed in smoke and ash, you should be prepared to evacuate if you’re instructed to do so, according to the Environmental Protection Agency.

Even if you’re far from flames, but the smoke is darkening your skies, your safest choice may be to leave, Dr. Prunicki said. If that's not feasible, the likely next best thing is to stay inside and take steps to limit your smoke exposure.

According to the E.P.A., vulnerable people like older adults, children and those with heart or lung conditions should avoid going outside when the air quality index — a numerical value from 0 to 500 that indicates air pollution and health risk levels — goes over 100. Anything over 150 means it's unhealthy for anyone to be outside without a high-quality mask.

You can consult AirNow's interactive fire and smoke map, a federally-run tracker for air quality conditions. PurpleAir can also offer a more local picture of air quality, as can other products and apps, like IQAir and BreezoMeter.

For children, safety concerns arise when the air quality index is even lower. Because breathing smoke can increase the risk of asthma in children and might even have irreversible consequences for their immune cells, experts recommend that, when the air quality index is above 50, caregivers should start thinking about keeping children inside, especially if they already have asthma.

Eduardo Medina

New York State officials said that an air quality health advisory, an alert that indicates a health concern related to pollution in an area, will be in effect for much of the state starting at midnight. Long Island, New York City, eastern Lake Ontario, Central New York and Western New York will be affected.

Felice Belman

On her way home from work on the Upper West Side of Manhattan, Genevieve Cruz was making a quick pitstop into the CVS on Amsterdam Avenue, hoping the pharmacy was still selling masks. "I used to have one on me all the time for Covid," she said. "I can't believe I don't even have a single one anymore."

Eduardo Medina

The North Carolina Environmental Quality Department said the state would be under Code Red or Code Orange air quality alerts on Wednesday because of the "rapidly rising levels of fine particle pollution attributed to smoke" from the wildfires. Officials are urging residents to stay indoors as much as possible, particularly those with asthma.