Smoke from Wildfires Is a Growing Health Threat to Both People and Birds

Olivia Sanderfoot hadn’t been too worried about the wildfire risk warnings on the morning of January 7, 2025. Such alerts were a part of California life. But when her husband texted her a photo of a blaze in the Santa Monica Mountains, she became nervous. She went outside her apartment in West Los Angeles and saw the billowing cloud of smoke in the hills. News of deadlocked traffic poured in as people started fleeing neighborhoods about 10 miles away. Sanderfoot picked up her nine-month-old son early from daycare and gathered some essentials, just in case.

By evening, the Palisades Fire evacuation warning zone was about a block from her home. She wasn’t taking chances. As an ecologist who has dedicated her career to studying the effects of wildfire smoke, Sanderfoot was not only worried about the fire itself; she was also terrified at the idea of her baby breathing its dangerous fumes, which can cause respiratory damage and other harm. “Even just thinking about the smoke in small quantities, I was like: ‘I am not doing this to my kid,’” she says. Amid sounds of sirens and whipping wind, the family got in the car to head to her father’s place a few hours away. Noxious smoke from a second conflagration, the Eaton Fire, briefly inundated the vehicle as they drove. 

Looking back, Sanderfoot recognizes how lucky she was to have a safe place to go and, ultimately, a home to which she could return. Many did not. These Los Angeles wildfires were among the costliest in the nation’s history, killing 31 people, ruining nearly 16,000 houses and other structures, forcing more than 200,000 people to evacuate, and burning 22,000 acres of open space and natural areas. Devastating as they are, those figures don’t account for a less visible, likely deadlier toll: Overall hundreds more people died in Los Angeles that month compared to a typical January. Poor air quality generated by the Palisades and Eaton fires is likely a major reason why. 

At one emergency room in the 90 days after the fires, visits for pulmonary illness surged 24 percent and heart attacks rose 46 percent. Abnormal blood work linked to general illnesses also more than doubled—a surprising and highly significant finding, says Cedars-Sinai cardiologist and researcher Susan Cheng. While all wildfires produce pollution, this smoke may have been particularly toxic given how many buildings, vehicles, and hazardous materials incinerated. The consequences for the millions of people exposed to the emissions will take years to unravel, says Cheng. She and dozens of other experts are collaborating on a 10-year research program to better understand the short- and long-term public health effects. 

Such investigations are increasingly important. Today larger and higher-intensity wildfires are generating more air pollution across North America, often hundreds or thousands of miles beyond the flames themselves. In 2020, smoke from western wildfires turned the skies of San Francisco and Seattle apocalyptically orange. The eastern United States suffered similarly in 2023, when Canada’s record-breaking wildfires exposed 43 million people from Chicago to Washington, D.C., to sooty air. In New York City, I experienced the worst air quality in the world at the time, and like many friends, I purchased my first air purifier. I’d long assumed wildfires were only a threat in the West. It felt like a wakeup call.

For Sanderfoot, who fell in love with birds as a senior in college, these intense smoke events confirmed that her research was on the right track. She and a growing number of scientists want to know how birds, too, fare when smoke pollutes the air and what people can do to help them. When she began looking into the question for her doctorate about a decade ago, she stood largely alone. “In wildlife ecology, we had often thought about air pollution as a done deal; we have the Clean Air Act,” she recalls. In an era of intensifying wildfires, we may need to think again.

Both people and wildlife are breathing dramatically easier than they did before Congress passed the Clean Air Act in 1970. Back then factories, power plants, and motor vehicles spewed emissions largely without federal limits, and smoggy skies obscured city skylines from coast to coast. By reducing multiple pollutants through decades of regulation and technological advancement, air quality steadily improved.  

As a result, millions of people who might otherwise suffer from asthma, heart disease, or stroke live longer and healthier lives. Birds benefit immensely, too. A 2020 study found that a Clean Air Act program aimed at reducing ground-level ozone, or smog, prevented the early deaths of some 1.5 billion birds in 40 years.  

Now smoke from wildfires is stalling and even reversing some of these invaluable air quality gains. “What the data really show is how rapidly we’re unraveling decades of progress we had made,” says Marshall Burke, director of Stanford University’s Environmental Change and Human Outcomes Lab. 

Take a regulated pollutant called particulate matter 2.5, or PM 2.5. These tiny particles are less than 2.5 microns in size—smaller than most of our cells—and become airborne when something burns, whether trees, grass, or fossil fuels. When we breathe them in, they work their way deep into our lungs and bloodstream, exacerbating respiratory ailments, increasing cardiovascular disease risk, and shortening lifespans, says University of Wisconsin-Madison air quality expert Tracey Holloway. Greater PM 2.5 exposure also correlates with higher rates of preterm births; lower fertility; increased dementia, depression, and autism; and less successful organ transplants. “When they study whether almost any adverse health outcome gets worse with air pollution, the answer is: It does,” Holloway says. 

That’s why the findings of a study that Burke conducted were so concerning. By combining air monitor data for particulate pollution with satellite imagery that tracks smoke plumes, he and his colleagues estimated that, in nearly three-quarters of the United States, wildfires between 2016 and 2022 were responsible for erasing 25 percent of PM 2.5 air quality improvements since 2000. Another study published this past June found a similar trend for smog over the past decade; again, wildfires are to blame. 

Are we headed back to 1970? Holloway doesn’t think so. Smoke isn’t nearly as pervasive as industrial pollution, she notes. But the effects of smoke can be severe and are projected to get worse: Extreme heat and drought fueled by climate change, combined with the misguided fire suppression policies of the 20th century and the spread of invasive species, are creating more flammable habitats in the 21st century. As a result, wildfires in North America are expected to continue emitting more greenhouse gases and air pollutants, and other regions around the world are similarly at risk, according to the World Meteorological Organization. Last September, one study estimated that PM 2.5 emissions from wildfire smoke are now responsible for 40,000 premature deaths per year in the lower 48 states—more than the number of U.S. residents killed in car crashes. The toll could increase to 70,000 by 2050 under current warming rates. 

Increased smoke, in other words, could become one of America’s deadliest climate disasters. Birds face the same exposure. The question is how they’ll respond.

Coal miners once carried around caged canaries for a reason: Birds are more sensitive to toxic air than we are. To support a rapid metabolism that fuels flight, their lungs process more oxygen with each breath. They also take in more pollutants. “Their efficiency is a double-edged sword,” says Lauren Hamlett, director of the wildlife program for Pasadena Humane. She treated wildlife for smoke inhalation during the Los Angeles fires last year. Many of her avian patients didn’t make it.  

Severe smoke also changes an animal’s visceral experience of its environment. “The smell is different. The sound is different. The sky is different,” Sanderfoot says. A bird could struggle to navigate, for example, or spot insects to eat. 

Still, birds aren’t helpless when skies get hazy, says Sanderfoot. While they can’t stay indoors or put on a mask, some may shift their behavior to limit their exposure—perhaps hunkering down and reducing their activities—or simply fly away. Ecologist Morgan Tingley, who was Sanderfoot’s postdoctoral adviser at UCLA, observed these varied responses when, in 2025, he donned an N95 mask and went into his yard as wildfires spread around Los Angeles. While his local Acorn Woodpeckers appeared to be sheltering in their cavities, he spotted Yellow-rumped Warblers overhead, seemingly leaving the burning area. Although interesting, however, such ad hoc observations alone aren’t enough to understand how different species cope in smoky conditions and how exposure affects birds’ survival or reproduction. 

Rather than trying to be at the right place at the right time when smoke spreads, ecologists are turning to a cornerstone of avian research: collaboration. Sanderfoot, who now works at the Cornell Lab of Ornithology, is launching an interdisciplinary network that brings together experts interested in smoke who are already collecting or analyzing all kinds of avian data. That includes sampling birds at banding stations, using recorders to monitor birdsong, affixing GPS tags to migrants, and working with community science databases such as eBird and Project FeederWatch. One of her latest collaborators is Adriaan Dokter, a colleague at Cornell who runs BirdCast, a program that uses weather radar to track mass avian movements. Smoke events tend to be widespread, and BirdCast measures migration across the contiguous United States, so it could help reveal if flight patterns shift in hazy conditions. “It’s a nice match,” Dokter says. 

While a lot of this research is in the early stages, some studies are already illustrating how smoke affects avian health, distribution, and behavior. “Everywhere we look, we find some response,” says Tingley. “That’s somewhat surprising and kind of unusual in the world of science. It means that the impact of smoke is relatively strong and appears to be pervasive across birds.” 

During wildfires in Oregon in 2020, for example, four Greater White-fronted Geese wearing GPS trackers diverted their migration paths hundreds of miles to avoid a smoke plume. Meanwhile, scientists tracking 21 American Robins in the state during the 2023 and 2024 wildfire seasons found that the birds were less active, but didn’t flee the toxic air. Smoky conditions have also been linked to reduced birdsong in eastern Washington State and New York and, according to North American Breeding Bird Survey data, to reduced bird diversity overall. And an analysis of two decades of data from the San Francisco Bay Bird Observatory concluded that birds were less active on and immediately after smoky days, and that chronic exposure to poor air was tied to lower body fat, which could put them at greater risk of starvation. 

Ornithologists are also concerned about the timing of smoke pollution, as wildfire seasons kick off earlier and last longer. Typically, conflagrations peak in late summer or early fall, as young birds fledge and migrants begin heading south. In recent decades, however, they’ve become more common during breeding and nesting. At the 2025 American Ornithological Society meeting, Tingley presented results from a preliminary analysis of two community science databases, NestWatch and Project MartinWatch. The data indicate that when smoke was present, four beloved cavity-nesting species—Eastern Bluebirds, Northern House Wrens, Tree Swallows, and Purple Martins—delayed laying eggs. The timing of other activities, such as hatching and fledging, also shifted. 

Ultimately, Sanderfoot hopes that gaining a nuanced understanding of how smoke affects different avian species will pinpoint ways for people to better support them. One of her recent initiatives, Project Phoenix, is directly aimed at that. During fire season, volunteers in three western states regularly conduct surveys at local spots, many of which have feeders and baths. She aims to use that data to determine whether birds are more reliant on such resources when the air is smoky. “That would suggest that there’s something that everybody can do to help,” she says. Other data, she says, could inform bigger-picture strategies, such as identifying and protecting patches of habitat that provide a refuge from smoke or determining which species are most vulnerable and when, and incorporating these threats into conservation plans. 

While such actions could ease the burden of smoke on birds, they don’t get at the root issue: uncontrolled wildfires. Slowing down climate change would reduce this threat and help all living creatures on many fronts. But there are other interventions at our disposal. Paradoxically, one of them involves producing a little more smoke.

For millennia, healthy landscapes in the West burned regularly. Lightning sparked some fires, and Indigenous peoples managed land with controlled burns. Mostly low in intensity, both natural and human-made wildfires created habitat for woodpeckers, nuthatches, and owls and also burned up flammable vegetation, decreasing the likelihood of massive blazes. 

In the 20th century, however, land managers in the United States and parts of Canada implemented a policy of extinguishing all fires at all costs. The underappreciated consequence: Natural “fuel” didn’t burn; it built up instead. When wildfires did inevitably start, their spread was fast and intense. 

Over recent decades, land managers have slowly relearned the lessons of the past and now recognize fire’s essential role in maintaining healthy ecosystems. From Audubon sanctuaries to private timberlands to U.S. Forest Service tracts, they conduct controlled burns to reduce wildfire risk. And while every fire inevitably generates smoke, over time low-intensity, intentional blazes are typically a win for air quality, emitting less pollution than the catastrophic fires they’re designed to prevent, Burke says. According to his recent research, expanding prescribed fires to 500,000 acres a year in California’s conifer forests—half of the state’s ultimate goal—could reduce fine soot by about 10 percent over a decade. “There is a net benefit to air quality,” Burke says, “but those benefits take time to accumulate.”

Despite these benefits, there are hurdles to implementing prescribed burns over millions of acres in the United States. This work has long been underfunded, and in many regions, there’s a backlog of sites to be burned. Recently Congress has sought to improve coordination and increase funding for fire prevention efforts, including through the Inflation Reduction Act of 2022. However, experts say that available resources still don’t match the scale required.

Public buy-in is another potential issue. While prescribed burns may improve long-term average air quality by preventing large wildfires across a region or state, the smoke they emit can impact the short-term air quality of people nearby. That can be a hard sell to affected communities. 

Regulations also complicate matters. The Clean Air Act treats wildfires as “exceptional events” beyond anyone’s control, allowing states to seek permission to strike smoky days from the record when calculating whether they’re meeting federal pollution limits. Under this policy, as wildfires worsen, the quality of the air people breathe could decline while states remain in compliance on paper. Meanwhile, because prescribed fires are planned and permitted, it is more difficult to have them qualify for exemptions. In states already struggling to meet pollution standards, this can make it harder for air regulators to greenlight beneficial burns, says Matthew Wibbenmeyer, an environmental economist at Resources for the Future, a nonprofit research group. 

The EPA has, in recent years, tried easing the permitting path, which many agree is needed. But clean air advocates are also wary of too much tinkering, especially as the Trump administration and Congress have pushed to weaken and roll back environmental protections. The Environmental Defense Fund, for example, lambasted a bill passed by the House of Representatives in April that proposes to redefine an “exceptional event” with language that the EDF says creates loopholes for industrial polluters.

Surmounting such challenges while protecting public health is possible. Leaders in southwest Georgia are showing how. Around the city of Albany, where quail hunting is a key economic driver, landowners rely on regular burning to prevent wildfires and preserve habitat. “There’s about 700,000 acres of privately owned hunting preserves, and fire is critically important to maintain quail habitat,” says D. Clay Sisson, who runs the Albany Quail Project.

In 2023, when the Biden administration was finalizing a rule to tighten federal limits for PM 2.5, Georgia officials, landowners, and nonprofits sprang into action. They wanted to meet the stricter standard while continuing their extensive use of fire. To do so, they developed a simple system that uses real-time air quality, wind, and weather data to determine where and when properties within 30 miles of Albany could conduct burns while minimizing the pollutants wafting into the city. The pilot project was a success, says Holly Nowell, smoke science director at Tall Timbers, a land conservancy and research group involved in the work. “We were able to burn 5,000 more acres last year,” she says, “while our PM 2.5 average did not increase.” 

Nowell hopes that the work offers a model for other regions seeking to prevent wildfires and create habitat through prescribed burns. At the same time, as climate change drives unprecedented blazes, it’s clear that prescribed fires and other land management strategies alone won’t be enough to ward off rising smoke pollution. Increasing wildfires in Canada’s vast tracts of boreal forests in particular are difficult to actively prevent or manage, and plumes don’t respect state or international borders. For all of these reasons, many communities are already preparing for a smokier future.

There’s no “safe” amount of smoke to breathe, and experts I spoke with emphasized the need to reduce our exposure to whatever degree we can. School officials in Oregon, for instance, are attending smoke readiness trainings and upgrading HVAC systems. Low-income residents in Southern California are applying for free air purifiers. In New York, people are visiting clean air centers and picking up masks.  

Still, it isn’t easy for strapped governments and institutions to prepare for and convey to the public the dangers of wildfire smoke amid an array of complex health and climate risks, such as heat waves, pandemics, and the spread of disease-carrying ticks. “We’re asking public health officials to communicate about yet another crisis, when they’re in the middle of 17 other major issues,” says Heidi Huber-Stearns, director of the University of Oregon’s Center for Wildfire Smoke Research and Practice. “We don’t want to inundate people with so many messages that they no longer can pay attention. It’s trying to figure out that balance.” 

When the Air Quality Index spikes, guidance centers around reducing outdoor activity and perhaps wearing a mask or staying indoors and running air purifiers. That’s especially important for sensitive groups, which include large swaths of the population: those who are young, old, pregnant, or have existing health conditions. Then there are outdoor workers who, like birds, can’t easily take shelter. A few states have passed regulations to protect these essential employees from both smoke and extreme heat—for example, by requiring employers to provide farmworkers with masks when it’s hazy. But advocates say such efforts often don’t go far enough. 

Even federal wildland firefighters don’t have access to adequate smoke protection, including respirators that meet the demands of long hours battling flames, says Riva Duncan, a former federal firefighter and president of Grassroots Wildland Firefighters. For years, this workforce has had to push for raises and better health care despite the higher risk of cancers, reproductive concerns, and mental health issues they face. “We’ve got to take better care of the people on the front lines,” Duncan says. 

Since forming in 2019, her group has taken on a range of issues, such as advocating to create a national wildland fire service and reducing on-the-job sleep deprivation. Duncan tells me about another focus: making it easier for workers to frequently change or clean their clothing, which gets covered in toxic soot. 

What Duncan says reminds me of research that Sanderfoot and another colleague, Allison Shultz, the associate curator for the Natural History Museum of Los Angeles County, are conducting. They’re studying how much soot accumulates on bird feathers and how hard it is for the birds to remove. Most of it, they’re finding, may persist until the animal changes its own outerwear—by molting. 

Wildlife, people, and landscapes on the vanguard of the climate crisis so often face similar challenges. With global fire patterns shifting and their emissions accelerating worldwide, a field of science called smoke ecology is emerging. From endangered orangutans in Borneo developing a cough after unprecedented smoke pollution in 2015 to Australia blazes in 2021 triggering marine algae blooms thousands of miles away, major smoke events affect a wide range of species and habitats well beyond the fires’ reach. A new framework, says Sanderfoot, can help researchers understand the interrelated or under-the-radar effects. “We’re really thinking about how smoke is changing ecosystems,” she says, “and how everything is connected.” 

As I was wrapping up this story during a July heat wave, the 2026 wildfire season was off to a severe start in both the United States and Canada, fueled by prolonged drought and intense heat. More than three million acres of U.S. land had burned as of June 30 (roughly 1.5 times the past decade’s average), and New York City was tinged orange once again, inundated by smoke from Ontario and Minnesota. I turned on my air purifier, feeling lucky that I have an indoor job. That evening, concerned friends asked me how the Mourning Dove chicks that had recently hatched on my apartment’s fire escape were managing.

Sanderfoot knows this reaction well. When smoke chokes the skies, some people find public health guidance overwhelming, but many immediately want to help vulnerable birds. Harnessing that instinct, she hopes, might spur people to think differently about fires, air pollution, and climate change. Eventually the skies will clear, but there’s no escaping the fact that this threat affects us all.

This story originally ran in the Fall 2026 issue as “Smoke Alarm.” To receive our print magazine, become a member by making a donation today.