Wildfires Burn Across Canada as Air Quality Improves in U.S.

Hundreds of wildfires are burning across Canada, displacing tens of thousands of people. In the eastern United States, the air quality continued to improve.

Source: AirNow · Data as of 6 a.m. Eastern.

Dan Bilefsky

MONTREAL — Hundreds of wildfires continued to burn across Canada on Friday, as residents braced for what could be the worst wildfire season in recent memory, and one that is far from over. But the storm system that sent clouds of noxious smoke into the United States was moving on, and air quality in the United States was improving for most.

Steven Flisfeder, a warning preparedness meteorologist at Environment and Climate Change Canada, predicted that the weekend could bring better air quality in Toronto, the country's largest city and its financial capital, thanks to some rain and cloud cover near wildfire areas, with scattered rains expected in parts of southern Ontario on Sunday.

"That's going to help flush out the contaminants from the air a little bit," he said.

Here's what else to know:

In Quebec, where nearly 150 wildfires this week diminished air quality in Ontario and the Northeast of the United States, Premiere François Legault said on Thursday that the number of evacuees had hit 13,500 but that he expected that number not to rise over Friday and Saturday.

The scale of the fires has stretched firefighting capacity across the country, and firefighters from the United States, South Africa, France, Australia and New Zealand, along with members of the Canadian Armed Forces, have been supporting local fire crews.

Drought in parts of Canada's western provinces contributed to the early, explosive start to the wildfire season in the country, experts say. Some parts of northern Alberta, which is under a heat warning, are seeing severe drought conditions, according to the Canadian Drought Monitor, a monitoring system the federal government maintains.

The eastern half of the United States could see some reprieve from the poor air by early next week when a cold front is expected to sweep through the region, the National Weather Service said.

Vjosa Isai contributed reporting from Toronto.

Remy Tumin

Canada's ferocious wildfire season has burned nearly 10 million acres and displaced more than 20,000 people. Many have been able to return home, but others are still stranded away from their communities.

Federal and provincial governments have pledged to match donations to the Canadian Red Cross for those affected by wildfires in Nova Scotia, Alberta and the Northwest Territories, raising more than $32 million in total so far.

Other fund-raising efforts have popped up from Canadian figures, such as Shawn Mendes, who released a song on Friday that he wrote this week in response to the wildfires. He said that he, too, would be making donation to the Red Cross.

Here are ways to help:

The Canadian Red Cross: Every $1 donated to the Canadian Red Cross will become $3 to support those affected by wildfires. The funds will be directed to people living in Nova Scotia and other Atlantic provinces, some of the hardest hit areas, for immediate and ongoing relief and recovery efforts as well as community preparedness initiatives.

United Way: The Canadian federal government joined the government of the Northwest Territories in a similar matching program to support disaster relief and recovery efforts. The funds will be used to support nonprofit community groups who are helping local residents.

Donate a Mask: This volunteer-run charity ships free N95-equivalent masks to anyone in Canada who requests them, with priority to Canadians who cannot afford or do not have access to high-quality masks.

Firefighters Without Borders: This Ontario-based nonprofit donates equipment and training to communities across Canada and in other countries.

Meagan Campbell and Dan Bilefsky

HALIFAX, Nova Scotia — As firefighters battled one of the worst wildfires in Nova Scotia history on Friday, one firefighter, Ralph Swansburg, said that the ground had been so brutally hot over the past two weeks that when an emergency helicopter dropped water on the blaze, it immediately "boiled" upon impact.

"It's been a very traumatic experience for everybody," said Mr. Swansburg, 46, a former wildland firefighter.

Mr. Swansburg has spent 11 days helping to fight a fire in Shelburne County, Nova Scotia, a rural area of about 14,000 on the maritime province's coast where the fire broke out late last month.

The fire has wreaked devastation, spreading toxic fumes across the bucolic area known for its white sand beaches and handsome lighthouse, destroying 150 buildings, including 60 homes, and forcing the evacuation of 5,500 people.

Shortly after the fire erupted, provincial firefighting authorities called Mr. Swansburg to pitch in. Mr. Swansburg, who currently manages a heavy equipment construction company in Shelburne, said he was eager to help. Since then, he has been working 14-hour days, using his excavator to dig firebreaks — the barriers wildfire fighters typically dig to try and slow or contain a fast-moving blaze.

Mr. Swansburg said the ferociousness of the fire had stunned him. "When you can watch a fire burn that intensely at 11, 12, one o’clock at night, that's unheard-of. Typically, at that time of night, it's just crawling along the ground," he said. In this case, he said, the fire was crowning, or jumping from treetop to treetop at breakneck speed.

"It's running, and it's going very fast," he said. "It's consuming the entire tree."

Mr. Swansburg was assisted from the air. "There was one day, I had a helicopter, he was basically babysitting me all day," he said. "I’d call him. He’d come and drop some water down."

Fighting wildfires was dangerous because trees could be standing one minute, and then fall the next, Mr. Swansburg said. "You always had to have your head on the swivel, looking for the fire," he said. "Since the fire burned many tree roots, the standing trees were very unstable. You just barely touch them, and they fall over."

While Mr. Swansburg has fought such blazes for many years, he said the sound of a wildfire was something a firefighter never forgets. He didn't get as close to it as some other crews did, but he recalled the sound of previous wildfires that he has fought up close.

"When it gets into a good thicket of trees, you can hear it coming," he said. "You can hear it roar."

Christopher Maag

As wildfire smoke from Canada arrived in the New York region, the skies turned dark and, around noon on Wednesday, the temperatures plummeted 10 degrees.

"Without a cloud in the sky — it was remarkable," said David Robinson, a professor at Rutgers University and New Jersey's state climatologist. For scientists studying climate change, he said, "there's a lot of research opportunities here."

Some of his colleagues agree. Events like wildfires and volcanic eruptions send clouds of particles into the atmosphere, reflecting some of the sun's radiation back into space and cooling temperatures on the ground. A growing number of climate researchers suggest humans should try something similar, if radical: Inject a thin layer of sulfates into the upper atmosphere, creating a heat shield to reduce temperatures around the planet.

Big wildfires like the ones that affected much of the continent this week could be used as natural experiments for such a project, helping researchers understand how ecosystems respond to more diffuse sunlight, said Daniele Visioni, a climate scientist at Cornell University.

In wildfires, as in the proposed solar radiation modification, "the principle is the same," said Mr. Visioni, who is seeking funding for experiments that would study the effects of wildfire shade on plants. "You reflect part of the incoming solar radiation, you cool the surface."

The risks of a chemically induced, planet-enveloping sun screen remain too complex to calculate. Preliminary research suggests it could partially deplete the ozone layer, make monsoons more unpredictable, cause lung damage or exacerbate geopolitical conflicts.

Daniel Schrag, director of the Harvard University Center for the Environment, acknowledges the idea has unknown risks. But, he said, it could also give humanity a few more decades to transition away from carbon-intensive energy sources. If humans continue to emit carbon at current rates without stratospheric protection, Mr. Schrag said, millions of people will die from heat stroke, floods, crop failures, droughts, and wars over drinking water.

"We know what's going to go wrong if we don't do solar engineering," said Mr. Schrag.

There's also the question of aesthetics. Some critics worry solar radiation modification might turn the earth's blue skies a milky gray, similar to the atmosphere over New York this week. Researchers including Simone Tilmes, a scientist at the National Center for Atmospheric Research, counter that sulfate chemicals would be injected so high up, and would spread so thinly across the stratosphere, they would be nearly invisible.

"Wildfires change the atmosphere dramatically. It's huge!" said Mr. Schrag. "Whereas what we’re talking about is a very tiny change, but over the entire planet."

For now, Mr. Visioni sees research opportunities in wildfires. How might plants respond to diffuse sunlight, caused either by wildfires or a radiation modification? Perhaps more important, how might humans?

"I’ve been thinking about this for the last three days: How do people react?" Mr. Visioni said. "I’ve been talking to my husband about how gloomy the sky looks."

Remy Tumin

Smog continued to blanket Raleigh, N.C., and the surrounding area on Friday as state officials maintained a code orange for air quality in the region. Forecasters are expecting a low pressure system to move in from New England on Saturday, which should help push the smoke out of the Raleigh area for good.

Dan Bilefsky

MONTREAL — With fires burning across Canada as summer approaches, Prime Minister Justin Trudeau warned Canadians this week to brace for a fierce wildfire season that could worsen as the heat intensifies.

Hundreds of out-of-control fires raged from the east to the west, evoking the feeling of a country under siege.

"Our modeling shows this may be an especially severe wildfire season throughout this summer," Mr. Trudeau told reporters, suggesting that areas not usually considered fire hot spots could be affected. "This is a scary time for a lot of people, not just in Alberta, but right across the country, including in the Atlantic, the North and Quebec, too."

Higher summer temperatures present a danger because drier conditions and high heat can kill trees and dry out grass, pine needles, and any other material on the bottom of the forest floor that act as kindling when a fire sweeps through.

Over 400 fires burned in Canada, and blazes this year have already scorched roughly 9.8 million acres of forest — more than 10 times the acreage that had burned by this time last year. The fires sent smoke billowing down the East Coast of the United States, from New York to Washington, D.C., and as far west as Minnesota.

According to the Canadian government, June projections indicate the potential for continued higher-than-normal fire activity across most of the country as a result of drought and long-range forecasts predicting warmer temperatures.

"We are already seeing one of the worst wildfire seasons on record, and we must prepare for a long summer," Steven Guilbeault, the country's minister of environment and climate change, said in a statement.

Ian Austen

This year's fire season in Canada has several dubious distinctions. It started earlier, the fires have been larger and more intense than is typical in the spring and fires are simultaneously spanning much of the country.

All that has left Canada's fire fighting system, which is divided among 10 provinces and three territories, under strain. Many Canadians are wondering if the country is adequately protected.

While provinces do share resources, when fires are burning in just about every corner of the country, sharing resources isn't really an option.

Canadian "resources are getting overwhelmed," said Mike Flannigan, who studies wildfires at Thompson Rivers University in Kamloops, British Columbia.

Canada's Armed Forces have also been in to help, though members are generally not fighting fires, but providing transportation and other logistical support.

In Canada, natural resources, like land, belong to the provinces so the country, unlike the United States, does not have large tracts of federally owned forestland. That means it lacks a large federal force to fight wildfires.

Canada's ability to tackle the blazes has also been hindered by provincial cuts to firefighting services, according to Jen Beverly, a former firefighter in Ontario who now studies wildfires at the University of Alberta.

And while dividing the system between 13 different agencies might seem inefficient, Ms. Beverly said that it does have advantages, namely local knowledge. As a firefighter in northeastern Ontario, where lakes provided abundant water, she said she often found it difficult to adapt when she was sent to fight fires in the arid mountains of the Yukon territory.

"There are risks when firefighters move across the country into terrain and conditions that they have no experience with," she said. "This is really dangerous work."

Rather than creating a special federal strike force for wildfires, Ms. Beverly said provinces should consider retraining and certifying retired firefighters to create reserve forces. Because wildfire fighting is a seasonal job and often performed by students or recent graduates, many retirees are still young enough and physically fit enough to do the work, she said.

"There's tons of people who could be called upon," she said. "It makes more sense leveraging the experience that already exists."

Vjosa Isai contributed reporting from Toronto.

Vjosa Isai

Wildfires are burning through millions more acres than ever before in Canada, and Indigenous communities, who have been stewarding these forests for thousands of years, may hold some answers.

Last week, the government announced it would be funding several hundred firefighting positions in Indigenous communities across the country, including to train 130 firefighters in the Yukon territory and northern British Columbia and another 425 in Manitoba.

Canada has turned to Indigenous people for conservation efforts in boreal forests, which are home to hundreds of reserves and provide a backdrop for traditional and cultural activities, such as trapping and herbal medicine gathering. About 40 percent of Canada's Indigenous population of 1.8 million still live on reserves.

Wildfires disproportionately impact Indigenous people because they often live in fire-prone areas, some remote and unreachable by emergency services over roads, according to a June 2018 parliamentary report.

Some have taken matters into their own hands. Two years ago, while a record-breaking heat wave exacerbated wildfires across British Columbia, some of the flames roared close to the Westbank First Nation, an Indigenous community in the Oakangan Valley. But years of thinning the forest and managing their land using cultural burning practices prevented the fire from causing any major damage to the community.

Also called prescribed burns, the practice involves putting a specific area on fire to incinerate trees, dead branches, brush and other materials that could otherwise be fuel for wildfires.

Some Indigenous communities feel neglected by the government. A concern echoed by many was the lack of resources to prepare for wildfires, or respond to them, causing a reliance on external agencies to come to their communities and complete the work, said Amy Cardinal Christianson, an Indigenous fire specialist for the country's national parks service.

Diverse communities have varying beliefs about the cultural significance of fire, but it is commonly seen as a gift by the creator and used to "put mosaics on the land," Ms. Christianson said, describing the image of contrasting green and charred patches on the landscape.

"When a fire gets moving, Indigenous people believe it's alive, it's breathing, as it's moving," and is thwarted when it hits one of the "mosaics," she said.

Still, as fires damage traditional lands, even down to the mineral soil, its effects threaten to prevent Indigenous cultural activities.

"For lots of people, the fire is over once the smoke leaves," Ms. Christianson said, "but for many Indigenous people, that's almost just the start."

Remy Tumin

They’ve come from as close as the United States and as far as the other hemisphere. They have brought reinforcements, and in at least one case, good cheer.

More than 1,100 firefighters from around the world have been dispatched across Canada to help combat the country's raging fire season, officials said, including groups from France, Chile, Costa Rica, the United States, Australia, New Zealand and South Africa.

Some of those countries have bilateral agreements with Canada to share firefighting resources. But, because the scale of the fires have stretched Canada's firefighting capacity so thinly, Canada has had to ask for extra help from new partners, said Marieke deRoos, a communications officer with the Canadian Interagency Forest Fire Center, which is coordinating the response to the fires.

Canada has called on help from their partners before, but "this magnitude is certainly unprecedented," she said.

Canada has mutual aid agreements with Australia, Mexico, New Zealand, South Africa and the United States, and nearly all have sent help. There are currently 352 firefighters from Australia deployed in the field; 295 are from the United States; 200 from South Africa; 46 from New Zealand; 40 from France; and one each from Chile and Costa Rica.

Firefighters from South Africa arrived in Edmonton with particular fanfare, performing a song and dance as they collected their gear. They were part of Working on Fire, a public works program that provides job training for young people, and are expected to be deployed for about a month.

#2023WoFCanadianDeployment Song and dance from #MZANZI1 as they arrive in Edmonton, Canada.#MZANZI1@environmentza@CIFFC@epwpza@kishugu pic.twitter.com/alj2IEnkuJ

"It was really heartwarming and touching for us," Ms. deRoos said.

More help may be on the way.

Ms. deRoos said Canada is also in talks with Spain and Portugal for relief.

Judson Jones

It is just after midday and air quality is improving in most of the Eastern U.S. There is still a widespread haze creating moderate conditions across much of the East but some locations like New York are reporting good air quality.

Dan Bilefsky

Martin Turgeon, a veteran Quebec City firefighter of 28 years, has seen it all.

He has pulled children from crashed cars. He was on the scene at the Quebec City Armory in 2008 when a raging fire tore through the building, the home of Canada's oldest French infantry regiment, reducing one of the province's most historic architectural gems, built in 1884, to ashes.

But as more than 150 wildfires convulsed Quebec this week, sending hazardous smoke billowing over Ottawa, Montreal, Toronto and traveling across the American northeast, Mr. Turgeon said wildfires often presented firefighters with a challenge of a different scale and intensity.

The massive fires simultaneously burning in Quebec have severely stretched the province's provincial forest firefighting agency, SOPFEU, which is equipped to fight about 30 fires at a time. So when two wildfires threatened the city of Sept-Îles last Friday, forcing the evacuation of 5,000 people, Mr. Turgeon didn't hesitate to volunteer.

He and his team of 11 firefighters traveled nearly eight hours by fire engine to the city, located in the Côte-Nord region of eastern Quebec, and helped secure critical infrastructure, including the city's water supply.

"When there is a fire, it is every man on deck and firefighters from across Quebec — and as far away as France — have rushed to help," said Mr. Turgeon, whose 24 year-old son Bryan is a firefighter, and who has a father who is a paramedic and an uncle who is also a firefighter. "Firefighting is in my blood," he added.

Fighting wildfires was especially difficult, he said, since forest fire firefighters had to contend with vast and highly flammable spaces, erratic weather such as wind and rain, and the need for heavy machinery like bulldozers and, in some cases, planes and helicopters to transport water.

"In a building, you have a door or window," said Mr. Turgeon, who is chief of operations for Quebec City's fire department. "A forest is so vast and that can mean fires that are vast, too."

Mr. Turgeon said that being a firefighter had long been his chosen vocation.

"It was my dream since I was a kid,’’ he said. "There is the adrenaline, you never know what you are going to get when you go for a shift at the station. But the main thing is the desire to help people."

Judson Jones

Light rain has been falling in parts of Quebec on Friday and that can be beneficial to fighting these wildfires. There is also a smaller chance of some thunderstorms, which could be more problematic because lightning strikes could trigger more fires and localized winds could make existing fires more erratic.

Somini Sengupta

With so much toxic wildfire smoke moving across the Canadian border and upending life across the Eastern United States, it raises a troubling question: Will there be more of this in the years ahead, and if so, what can be done about it?

First, let's take a step back. Global average temperatures have increased because of the unchecked burning of coal, oil and gas for 150 years. That has created the conditions for more frequent and intense heat waves.

That extra heat in the atmosphere has created a greater likelihood of extreme, sometimes catastrophic, weather all over the world. While that doesn't mean the same extremes in the same places all the time, certain places are more susceptible to certain disasters, by virtue of geography. Australia could see more intense drought. Low-lying islands are projected to experience higher storm surges as sea levels rise.

In places that become hot and dry, wildfires can become more prevalent or intense.

The unifying fact is that more heat is the new normal.

The best way to reduce the risk of higher temperatures in the future, scientists say, is to reduce the burning of fossil fuels. There are also many ways to adapt to hotter weather and its hazards.

Eastern Canada, which erupted in extraordinary blazes, is projected to be wetter, on average, especially in winter. The projections are less clear for summers, when soil moisture is important for creating fire conditions, according to Park Williams, a climate scientist at the University of California, Los Angeles.

Eastern North America is also projected to become much hotter, with many more days when the maximum temperature will climb above 35 degrees Celsius, or 95 degrees Fahrenheit, according to the Intergovernmental Panel on Climate Change.

So, in a dry year, the extra heat is likely to aggravate fire risks. That's what happened this year in parts of Quebec. Snow melted early. Spring was unusually dry. Trees turned to tinder.

The Northeastern United States is also projected to be wetter in the coming years. But as Ellen L. Mecray, the eastern regional climate services director at the National Oceanic and Atmospheric Administration, said, "We have also been experiencing seasonal droughts more often, in part due to increasing temperatures, changing precipitation patterns, and loss of soil moisture."

As for air pollution, she said, wildfire smoke from the West, even dust across the Sahara, can travel across the globe to the United States, bringing with it hazardous particulate matter, according to the latest National Climate Assessment, published in 2018.

"From a human health perspective, we are concerned about the frequency and duration of such smoke events," said Lesley-Ann Dupigny-Giroux, a climate scientist at the University of Vermont who led the report's Northeastern U.S. chapter.

First, heat. By 2035, according to the National Climate Assessment, average temperatures are projected to increase by more than 2 degrees Celsius (3.6 degrees Fahrenheit) from the preindustrial era. That's larger and earlier than the global average.

Rising average temperatures increase the chances of more frequent and intense heat waves. That's especially risky for people who work outdoors or who cannot afford air-conditioning.

Second, for coastal areas of the Northeast, there's the risk of sea level rise. That means flooding dangers affecting millions of people. Cities have long been warned to prepare by improving drainage, opening up floodplains, planting shade trees and encouraging better insulation for buildings.

In the Southeastern United States, climate models indicate "increased fire risk and a longer fire season." Fires ignited by lightning (as opposed to humans) are projected to increase by at least 30 percent by 2060, the National Climate Assessment said.

In Western states, the wildfire season is already longer because of higher temperatures, drought and earlier snowmelt. By midcentury, the assessment concluded, the area burned there could at least double.

California could get a break this year because of a wet winter and spring. But not necessarily the Pacific Northwest. Dr. Williams, the climate scientist, said that "if a major heat wave occurs in that region this summer, I expect that fuels will be plenty dry to sustain large fires."

Most fires in Quebec appear to have been started by lightning. Elsewhere, such as in the Western United States, human carelessness and the mismanagement of aging power lines have led to catastrophic fires. Both are fixable problems.

Fire experts say that the mechanical thinning of forests, as well as "prescribed burns" — the intentional burning of underbrush — can also reduce the spread of wildfires, but with risks.

Some things that protect people from heat also help protect from wildfire smoke. Leaky, poorly insulated buildings are as hazardous on hot days as they are in smoke.

The most efficient way to keep temperatures from rising further is to reduce the combustion of fossil fuels. They are the drivers of heat and its hazards.

Norimitsu Onishi

St-FELICIEN, Quebec —More than 100 French firefighters have arrived in Quebec to help battle an outbreak of wildfires that is threatening several communities in northern Quebec, including one of its biggest cities, Chibougamau.

The firefighters, who landed in Quebec City on Thursday, were expected to arrive on Friday evening in Roberval, a city where Quebec's fire agency has based its operations and where many evacuees from Chibougamau have taken shelter.

"We plan to be operational on Saturday morning,’’ said Lt. Col. Jérôme Bonnafoux, a spokesman for a team of firefighters from Hérault, a department in southern France.

Quebec is expected to also receive additional reinforcements from other countries, including the United States and Portugal.

About a third of the 400 wildfires burning in Canada are in Quebec, a province that has experienced its worst wildfire season on record, with three months left in the wildfire season. The fires have scorched roughly 1,603,700 acres of forest so far, compared with an average of 3,326 acres at the same date for the past decade, according to the Quebec government.

Fires had moved closer on Friday morning — within 9 miles — to the city of Chibougamau, though winds were favorable and blowing in the opposite direction, Nichèle Compartino, a city councilor, said by phone from Chibougamau.

"But the winds could change suddenly,’’ Ms. Compartino said.

Roads to Chibougamau and other evacuated communities in the area remained blocked on Friday, and it was not clear when the city's 7,500 residents would be able to return. Residents were forced to suddenly evacuate on Tuesday evening after fires came within 15 miles of the city.

Aishvarya Kavi

Life continued on in the nation's capital. A group of Marines gathered on the steps of the Lincoln Memorial to celebrate one of their own being promoted to major. Jason Bullis said he had been nervous about the forecast, but was glad the air was clearer. "Yesterday I was going, ’Ooh, it's pretty smoky,’" he said.

Jacey Fortin

As wildfire smoke engulfed skies across eastern North America, it brought echoes of the coronavirus pandemic. Children were forced off playgrounds and cooped up inside. Adults dug out N95 masks. Brightly colored maps tracking public health threats presented a whole new language of risk.

For many in the worst-hit places, the anxiety and stress came tumbling back, assuming it had ever left.

"I think this goes to show that the mental health impacts of Covid have, in some ways, persisted," said Sarah Lowe, a clinical psychologist and associate professor at the Yale School of Public Health, "and that Covid's impacts have a longer tail than we would like."

Dr. Lowe spoke to the idea of "cumulative, collective trauma," with stressful, unfamiliar events piling up on one another. "There's an additional wear and tear on our psyches," she said.

For Chloe Bambara, 23, the hazy orange air she woke up to in Washington, D.C., on Thursday — and the desire to see it lift quickly — brought flashbacks to the uncertainties and false hopes of early 2020, when nobody knew when, or if, the pandemic would end.

It did not help, she said, that faraway forest fires, as well as broader global trends like climate change, felt largely out of her control, just as Covid had.

"A lot of people in my generation might feel this way, too," Ms. Bambara said. "Is this going to be the new normal? Is this what we have to look forward to?"

Still, she said, there was a "weird silver lining" to the parallels: She already had N95 masks on hand.

Dr. Lowe saw another possible silver lining, as well: In some cases, she said, stressful shared experiences like the pandemic and wildfire smoke "can motivate action, both initially and also thinking longer-term about how we, as a human population, are going to face climate change."

Ian Austen

TORONTO — Canada's fire prevention capacity and efforts have been shrinking for decades, because of budget cuts, a brain drain from the country's forest service, and red tape, turning some of the country's forests into a tinderbox.

At a time when many Canadians are asking if the country has enough wildfire fighting resources, several experts say the country should be focused on doing all it can to prevent wildfires.

"We need to do more to get ahead of the problem," said Mike Flannigan, who studies wildfires at Thompson Rivers University in Kamloops, British Columbia, a community in the heart of that province's wildfire country. "And progress on that has been slow, primarily because we are kind of stuck in this paradigm that fire suppression is the solution."

British Columbia spent 801 million Canadian dollars (about $601 million) on fighting forest fires during an unusually hot year that saw fire wipe out the town of Lytton. But the province's current wildfire prevention budget is just 32 million dollars a year.

That disparity exists in other provinces, which tend to invest in small, community-based programs that protect villages and towns rather than mitigating the risk of fire throughout forests.

The small programs are helpful, involving measures like clearing forest floors on the periphery of towns and creating fire breaks between settlements and forests. But to avert runaway wildfires, broader measures are necessary.

It is a provincial responsibility that the federal government could help with, Professor Flannigan said. There has to be "adequate funding to the provinces to scale up mitigation strategies from just small community based programs to thinking about entire landscapes," he said.

Remy Tumin

In New York City, life was slowly returning to the pre-haze days. I saw many commuters wearing masks on the subway the last few mornings, but today, they were few and far between.

Aishvarya Kavi

Washington's mayor, Muriel Bowser, has issued a code orange air quality alert for the nation's capital on Friday, although in most of the city and surrounding areas the Air Quality Index has dropped to well below 100.

Aishvarya Kavi

D.C. parks and the National Zoo reopened Friday, but D.C. public schools have continued to suspend outdoor activities.

Aishvarya Kavi

The monuments in Washington appear clear against blue skies, and tourists and commuters alike have not been wearing masks.

"It's way more clear," said Kay Rich, 19, who sells drinks out of a cooler on the National Mall and had never seen anything like yesterday's heavy smoke. But today, "you can see the sky more, and you can't really smell it."

Aishvarya Kavi

Organizations that work with unhoused people in the New York and Washington metropolitan areas say the pandemic has prepared them to protect that population from hazardous wildfire smoke.

The toxic air quality has only underlined the vulnerability of unhoused people and the urgent need for solutions like affordable housing and access to medical care, advocates say.

Joe Mettimano, president and chief executive of Central Union Mission, a faith-based nonprofit organization that provides services to the homeless in Washington, said that experience with Covid had enabled the group to respond quickly to the unprecedented conditions in the capital on Thursday.

"We saw a little bit of an increased number from what we normally see on a weekday when the weather is nice," Mr. Mettimano said. He said the group's shelter was handing out masks and was prepared to expand the number of available beds on Thursday night.

"This reminded us of Covid," said Susie Sinclair-Smith, the executive director of the Montgomery County Coalition for the Homeless, which runs the main emergency shelter for men in the Maryland county that borders Washington.

The coalition followed an approach it took during the pandemic that successfully kept the infection rate low in their shelters: educating the hundreds of people it serves, including those with disabilities who are permanently housed but require regular support services, about the severity of the smoke in the air, symptoms associated with exposure to it and ways to seek help if they experienced symptoms.

"It's become increasingly clear to us that homelessness and public health are interconnected," Ms. Sinclair-Smith said.

Organizations in Washington and New York that do direct outreach with the street homeless have also been reaching out to those they interact with regularly, pointing them to shelters with open beds, places they can go to be indoors and other resources, like free bus services in Montgomery County on Thursday. Others have distributed masks and staples like food and water.

Most said that they had not encountered medical emergencies among the street homeless caused by exposure to the smoke, but that exposure alone was concerning given that life expectancy among the homeless is already far below that of the average American, largely because of chronic illnesses.

John Mendez, the chief executive of Bethesda Cares, an organization that works to end homelessness in Montgomery County, said the air quality concerns only highlighted the importance of moving the homeless into permanent housing and increasing the number of medical providers who work with those populations.

"We often say that housing is health care," Mr. Mendez said. "This is one of those times."

In a statement, Dave Giffen, the executive director of the Coalition for the Homeless in New York stressed that the city's Right to Shelter mandate had helped to shelter thousands of people who do not have homes from the toxic air, and criticized Mayor Eric Adams's attempt to weaken it.

"The air quality crisis hitting New York City is another reminder that safe shelter saves lives," Mr. Giffen said, adding that Mr. Adams "should be focusing on providing even more safe spaces for those currently sleeping on our streets."

Andy Newman contributed reporting.

Jon Hurdle

In Philadelphia, the air quality was much better on Friday morning than in the last two days. Ashley Fischer, an editor for a medical publisher, was walking to work for the first time this week, having worked from home during the air-quality alert because of the smoke pollution. "The air is so much better today," she said. "It has significantly improved."

Jon Hurdle

Ms. Fischer, 37, said she wore a mask for any trips outside over the last two days but was walking without a mask on Friday during her one-mile journey to work.

Jesus Jimenez

New York City zoos and the New York Aquarium will reopen today, citing improving air quality.

Jenny Gross

New York City's smoke-clogged air reached 407 on the Environmental Protection Agency's 500-point Air Quality Index at one point this week, signifying that pollution levels were "hazardous" and at historically dangerous levels.

But it's not the worst air quality that the United States has seen. There have been about 40 times over the past decade when the index has risen above 500, into what the E.P.A. calls "Beyond the A.Q.I." Most of those instances have occurred in Western states, including California, Oregon and Washington, the E.P.A. said in an email, as wildfires spread a blanket of smoke over parts of the region.

The E.P.A. in 1999 released the current version of the six-tier index as a way to communicate to the public the density of five pollutants. A rating anywhere between 301 and 500 is considered "hazardous," and air quality at that level will trigger health warnings. At that level and beyond, everyone should stay indoors and reduce activity levels. "Use the same information that is for the ‘hazardous’ category," the E.P.A. advises.

While the A.Q.I. measurement used in the United States does not support values above 500, such values occur so infrequently that the issue rarely comes up, said Robert Rohde, the lead scientist at Berkeley Earth, an organization focused on environmental data science.

"Such levels do occur more often in some foreign countries, such as India," Dr. Rohde said. Some third-party air quality tracking platforms extend the U.S. A.Q.I. scale and track figures over 500, he added.

Harshal Salve, a professor at the All India Institute Of Medical Sciences in New Delhi, said that as air quality reaches hazardous levels close to or above 500 on the U.S. A.Q.I. scale, people will experience symptoms of respiratory illnesses, such as coughing and a burning sensation in their eyes, with people over 65 years and under five years at the highest risk.

The negative effects can continue even after air quality levels have improved, since pollution particles can cause inflammation of the lung tissue and increase the vulnerability to infections.

By Friday, the cities with the highest A.Q.I.s were seeing improved air quality, with Susquehanna Valley, Pa., at 150, down from 448 on Thursday morning, the highest of anywhere in the United States, according to AirNow, a source for air quality data. Levels below 100 are considered to be below the level known to cause adverse health effects.

The E.P.A. said it has proposed changes to the A.Q.I. to make it more accurately reflect recent scientific studies about particle pollution and health, and to improve the quality of monitoring data. The agency said air quality in the United States is generally improving, even if climate change is contributing to more frequent and severe wildfires.

Olivia Clifton, an atmospheric scientist at NASA Goddard Institute for Space Studies, said that if air quality levels like the ones this week become more frequent, the E.P.A. should consider defining what A.Q.I. levels above 500 say about air quality for the public.

"Is this still hazardous or beyond hazardous?" Dr. Clifton said. "What is the qualitative description of the air quality that would need to be described for a higher A.Q.I.?"

Chris Stanford

Here are the air quality indices for several major cities at 7 a.m. Eastern time. The index runs from 0 to 500; the higher the number, the greater the level of air pollution. The index in some places was less than half the number on Thursday. Find your city here.

Baltimore: 71

Buffalo: 95

Chicago: 62

Detroit: 109

New York: 69

Philadelphia: 131

Pittsburgh: 119

Richmond, Va.: 134

Washington: 76

In Canada, which does not use the Environmental Protection Agency's index, the major city with the worst air quality on Friday morning was Saskatoon, Saskatchewan, which was described as "unhealthy."

Derrick Bryson Taylor and Judson Jones

People in the Great Lakes and Mid-Atlantic regions will again face smoke from Canada's wildfires on Friday, capping a chaotic workweek that brought hazy conditions and poor air quality to millions of people as far south as North Carolina. However, based on a New York Times analysis of the forecast models, there will be far less dense concentrations of wildfire smoke for most people on Friday.

Pockets of dense smoke could significantly reduce air quality and lead to low visibility, the National Weather Service said early Friday, singling out areas around southern Ontario and across parts of Pennsylvania. Pittsburgh and Philadelphia could be the two cities that see the worst of the smoke Friday, but even then it should be better than it has been.

A wider region across the eastern United States of light to moderate haze may continue to lead to opaque skies and orange sunsets and sunrises, which have dotted social media profiles this week.

Air quality alerts were in effect for parts of Connecticut, Delaware, Indiana, Michigan, New Jersey, New York, Ohio and Pennsylvania. While most alerts were scheduled to expire at midnight Friday night, a smaller number will end earlier in the day, by early afternoon.

Smoke from Canadian wildfires continues to be transported south by winds into the U.S. resulting in moderate to unhealthy air quality across parts of the Northeast, Mid-Atlantic, Ohio Valley, and Midwest on Friday. Some improvement is expected this weekend. Excessive rainfall may… pic.twitter.com/NMfv6Ft7Dn

Although most of these areas could still see worse air quality than normal, nothing is expected to be anywhere close to the historic levels on Wednesday and Thursday in New York.

There, the air is "much improved," said forecasters with the Weather Service. However, the air quality levels were still predicted to be greater than 100 on the Air Quality Index. Officials once again recommended limiting strenuous outdoor physical activity. Farther west, in Michigan, weather forecasters said an air quality alert would be in effect until noon, and said pollutants in certain areas were expected to be unhealthy for sensitive groups and may occasionally rise to an unhealthy level.

The breath of fresh air that everyone has been hoping for should come Saturday as the stubborn storm system drawing in the smoke from the north and into the Northeast should begin to move slowly out of the region.

See maps of where smoke is traveling and how harmful the air has become across the region.