Wildfire SmokeSkies Darken as Air Alerts Are Issued Across Northern U.S.

“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 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.

“It’s still pretty yucky out there,” said Ms. Eyk, speaking 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.”

Smoky skies hung over eastern Ontario on Tuesday, with few shadows cast by the obscured sun in Ottawa. The capital, Kingston and Belleville all recorded some of the highest risk ratings on the province’s air quality health index.

A cold front on Saturday is slated to shift the winds back east, blowing lingering smoke out, and could bring scattered showers in Toronto, Ms. Eyk said.

Mr. Delfuoco recently took up photography and wanted to shoot sunsets and reasoned that the smoke in the air would allow him to capture some particularly vivid colors. He and a friend, Jillian LaPoint, drove 40 miles from Syracuse to Breitbeck Park in the city of Oswego, N.Y., on Lake Ontario, a popular sunset photography spot.

He dusted off a box of surgical masks left over from the coronavirus pandemic just to be safe. “It definitely felt kind of nostalgic to put one on,” he said.

Mr. Delfuoco’s bet about the sunset proved to be correct, though clouds eventually blocked his view. The smoke gave the sun a brilliant reddish-orange tint.

“It was like nothing I had ever seen before,” he said. “It was just red the whole time.”

“It was like an orange haze,” Ms. LaPoint said. “It kind of looked like the apocalypse was coming.”

In Fairport, N.Y., outside of Rochester, a man reported a light purple sky and a “sickly blood-orange” sun.

And in Macedon, N.Y., Ann Schauman described the sky as beige and the sun as bright red.

“I’m on a hill, so I’ve been able to see this smoke-fog, whatever you call it, very clearly,” said Ms. Schauman, owner of Ann’s Purple Produce, a small organic farm. “I’ve lived on the land 48 years and I’ve never seen anything like it out here.”

The heaviest smoke was projected to reach the southeast corner of the state, where fine particle levels were expected to reach the red category, which is considered “unhealthy for everyone,” according to the Minnesota Pollution Control Agency.

In east central Minnesota, which includes the Twin Cities, pollutant levels were expected to reach an orange category that is considered to be unhealthy for sensitive groups, the agency said.

The heaviest smoke was expected to be near Rochester and Winona, about 100 miles southeast of Minneapolis.

The air quality on Tuesday night appeared to be normal in the state, according to a forecast map on the agency’s website. In Minneapolis, the sky was mostly cloudless in the evening.

Smoke was expected to linger in east central and southeast Minnesota through late Tuesday, the agency said.

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.”

“The eeriness of it all, it really drew me in,” said Mr. Berman, who lives in Rego Park. “It’s like Halloween in spring.”

In downtown Manhattan, foot traffic was sparse. Those outside held phones aloft and snapped pictures. Outdoor tables at one Italian restaurant were untouched. From the Battery Park Esplanade, the outline of the Statue of Liberty was barely visible.

“I didn’t notice it until my throat started hurting,” said Liz Flores, who operates a fruit and grocery stand at the corner of 231st Street and Broadway. She plans to wear a mask tomorrow.

“What is happening out here?” Luis Nazario, 35, shouted in the street, nearby. He was helping a customer with bags at the Lot-Less. He said he had a headache all day. “Since earlier I was like wondering why it’s so smoky,” Mr. Nazario said. “This looks like, have you seen ‘Crow’? ‘City of Angels’? It’s kind of like what the film looks like.”

In Williamsburg’s Domino Park Jocelynn Loebl wore a black mask as she walked her dog. “I’d rather keep that smoke out of my lungs,” she said. “I’m coughing.” She had words of mock gratitude for the smoke’s source: “Thanks, Canada.”

Ayse Muratoglu took photos of the skyline with her cellphone and spoke in apocalyptic movie terms. “It’s pretty scary, very ominous, quite eerie, almost in a cinematic sense,” said Ms. Muratoglu, a marketing manager for a natural food company.

Leo Prather, 27, and his girlfriend Bernice Noel, 25, said their asthma had been exacerbated by the smoke. “I coughed real hard earlier in the day, and I couldn’t understand why,” Mr. Prather said.

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.

The images from those fires — cities glowing under orange skies, smoke billowing around tourist havens and heritage sites, woodland animals badly injured and killed — have become grim icons of this era of unsettled relations between humankind and nature.

“The heating of the planet is turning landscapes into tinderboxes,” said the report, which was published by the United Nations Environment Program.

The report, produced by more than 50 researchers from six continents, estimated that the risk worldwide of highly devastating fires could increase by up to 57 percent by the end of the century, primarily because of climate change. The risks will not be distributed equally: Some regions are likely to see more fire activity, while others may experience less.

In some regions with long histories of brush fires, such as eastern Australia and the western United States and Canada, they have become more intense over the last decade and are ravaging larger areas, the report found.

In a moderate scenario for global warming, the likelihood of extreme, catastrophic fires could increase by up to a third by 2050 and up to 52 percent by 2100, the report estimates. If emissions are not curbed and the planet heats up more, wildfire risks could rise by up to 57 percent by the end of the century.

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.

And keep in mind that no mask will protect you 100 percent. “Wearing an N95 reduces your exposure, but if you have to go out, you will get exposed,” Dr. Balmes said.

There’s also some evidence that you may want to protect your skin when you go outside. In a first-of-its-kind study published in 2021, researchers found associations between short term smoke exposure and health care visits for itchy skin and eczema.

Some skin care creams and products with labels like “antipollution” or “pollution protection” probably won’t help much. Though applying a lotion with emollient properties — like shea butter, lanolin or petroleum jelly — before you go outside may help create an artificial barrier on your skin. Dermatologists advise that you avoid smoke if you can, cover up with long sleeves and pants if you have to go outside, and cleanse your skin after spending time outdoors to remove any pollutants.

“When the sun rises, it’s an unusual bright orange color,” said Richard Linn, of Orchard Park, who is out early every morning with his dogs. “There’s a decidedly smoky smell,” he added.

In Buffalo’s northern suburbs last Friday, the smoke created the conditions for a peculiar sunset. The sun was a deep, bright orange and, at times, appeared as just a small point in the sky, as if it was sinking into the haze.

A local TV station published footage from a webcam overlooking downtown Buffalo, where the smoke appeared thick enough to look like fog.

In Oswego, on the shore of Lake Ontario, the smoke created a haze that settled over the city on Tuesday and gave the sky a yellowish tint most of the day. By evening, a steady breeze had picked up but the smell of smoke was still detectable, and the streets were mostly empty.

School districts in Oswego County canceled athletic events and outdoor after-school activities. The Oswego Little League said it was canceling all of its games out of an abundance of caution. Even a planned D-Day ceremony in the nearby city of Fulton to honor a soldier who received the Medal of Honor for his actions on June 6, 1944, was postponed.

In Manhattan Tuesday evening, some commuters were startled by smell.

At the subway station at West 86th Street and Broadway around 6:45 p.m., passengers trudged up the stairs and onto the street and gasped. The sky was a strange orange-gray, and the cool air smelled of smoke.

“This morning, it smelled like burnt toast, but now it’s more like campfire,” said Benjamin Lukas, 47, who was on his way to his mother’s apartment to cook her dinner. “It’s just wild.”

Mr. Lucas worried about his mother’s breathing — and hoped that she had her windows shut, despite the cost of air-conditioning.

Up the street, Genevieve Cruz was making a quick pit-stop 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.”

For some New Yorkers, the news of the Canadian wildfires came as a surprise, even as they breathed in the smoky air. “That’s what this is?” asked Joe Lerner, as he stood waiting for a crosstown bus. “I figured it was a building fire or something.” Already, he said, his throat felt a little sore.

While ash and soot from burning wood are some of the most concerning types of particle pollution, wildfire smoke can also contain other toxic and cancer-causing substances, including chemicals, heavy metals and plastics. Indeed, said Dr. John Balmes, a pulmonologist and professor of medicine at the University of California, San Francisco: Smoke from fires is “pretty much like tobacco smoke without the nicotine.”

Breathing in wildfire smoke can make anyone cough, wheeze and struggle for air. It can irritate your eyes, nose and throat, and cause headaches.