They never thought the fires would reach them. They lived in cities, after all, far from the parched, combustible wilderness. There’s the woman who never expected to have to grab her 1-year-old out of her bed in the middle of the night, shielding her soft head from a hailstorm of flaming embers as she dashed to the car. Or the mom of two who wound up on the beach holding her youngest, a 9-week-old baby, wondering how she would swim if the fires bearing down on her from the hills above forced her into the ocean. Or the pregnant asthmatic who had to decide where to put her air purifier as suffocating smoke blanketed her neighborhood — in her own bedroom, or the bedroom of her eldest child. The women don’t know each other, but they share the same instinctive feeling that they didn’t know enough — and didn’t do enough — to keep their children safe. As urban sprawl encroaches on wilderness — and as the planet grows drier in many places and hotter almost everywhere — wildfires are becoming more dynamic, unpredictable, and far-reaching, affecting broader and broader swaths of the world’s population. On the east coast of Australia and the west coast of the United States, two of the planet’s most densely populated wildfire hotspots, millions now find themselves in the midst of a public health crisis that is not yet fully understood. Even fires that are limited to wilderness can blanket major cities in levels of pollution that are without recent precedent, leaving residents to guess how to protect themselves and their families. And when wildfires push through city limits, they incinerate synthetic materials, vehicles, and buildings, producing a mix of pollutants more toxic than the smoke that comes from burning vegetation. None of this is theoretical. It’s been six years since Australia’s so-called Black Summer coated the country’s east coast in choking smoke, three years since 100 million Americans were exposed to deadly pollution from Canadian wildfires, and just one year since fires decimated neighborhoods in Los Angeles, destroying about 13,000 residential properties and killing 31. But Australian and U.S. public health systems are ill-prepared for the inevitable return of such blazes. Nowhere is the lapse more clear than in the paucity of guidance provided to pregnant people. Scientists are just beginning to study how pollution from fires affects babies in the womb, and warnings from public officials and doctors consistently fail to account for the most vulnerable. Years after prolonged exposure to wildfire smoke during pregnancy, parents are left wondering whether asthma, developmental delays, and other health problems suffered by their children began with what was in the air before they were born — and whether it’s safe to raise a family in a place where every summer brings the same threat back to their doorsteps. Smoke shrouds the Sydney Harbour Bridge during the Australian bushfires in November 2019. Bai Xuefei / Xinhua via Getty Images Anneke French was excited for her maternity leave. A nurse at Canberra Hospital in Australia’s capital city, French was in her third trimester in the spring of 2019. Many in her tight-knit group of childhood best friends were also preparing to give birth or already had babies of their own. ‘We were really looking forward to getting out and having lots of free time to go and have ladies’ lunches, or do some things by ourselves to treasure our time before we had a newborn to care for,’ she remembered. But by the time her leave began, French was preparing for a very different kind of summer. Earlier that year, in the depths of Australia’s winter, parts of Queensland and northern New South Wales began to burn — an ominous start to what is typically the country’s quietest fire season. By spring, new blazes were flaring along the east coast, feeding on vegetation desiccated by years of drought. Strong winds pushed flames across parched forests and grasslands, while dry lightning strikes sparked new fires faster than crews could contain them. Summer brought unprecedented heat waves; temperatures rose higher than most Australians had experienced in their lifetimes, cresting to 120 degrees Fahrenheit (49 degrees Celsius) in some areas. Hundreds of fires broke out across southeastern Australia, burning millions of hectares of land. More than two-thirds of Australians were exposed to flames or smoke, making it the most far-reaching environmental disaster in the young nation’s history. While fire never touched central Canberra itself, the city endured some of the most prolonged and suffocating air pollution in the country, at times registering the worst urban air pollution in the world. Any air quality reading above 300 is considered hazardous, the index’s highest category of warning. Canberra’s reading exceeded 5,000 on New Year’s Day 2020. Australia’s Black Summer smoke Surface PM2.5 over eastern Australia and the Tasman Sea, 1 December 2019 to 31 January 2020 — Surface PM2.5 · µg/m³ (log scale) Play 5 50 500 Source: Copernicus Atmosphere Monitoring Service (CAMS) global reanalysis (EAC4) Clayton Aldern / Grist Throughout the crisis, pregnant women and new parents in smoke-affected areas, tasked with the responsibility of protecting both themselves and their infants, were largely given the same public health guidance as other sensitive groups (the elderly, asthmatics, and people with diabetes): Stay indoors as much as possible. Even French, a nurse, couldn’t find reliable guidance on what more she could do to protect herself and her baby from the smoke. At a prenatal appointment several weeks before her due date, French’s obstetrician told her to avoid going outside. She stayed indoors as best she could, preparing the house for its newest arrival. But the smoke worried her. ‘The smell was strong enough that it felt dangerous,’ she said, ‘like you would feel if you were too close to a bushfire and felt it was time to evacuate.’ One night when she was a little more than 35 weeks pregnant, French felt a stabbing pain in her stomach so severe she could hardly take a breath. She and her husband, James, rushed to the hospital, where their obstetrician quickly discovered that French had a placental abruption, meaning the placenta was partially or fully removed from the walls of the uterus, cutting the baby off from its source of oxygen. The condition is usually preceded by either sudden trauma like a severe fall or chronic maternal cigarette smoking. French had not fallen, and she didn’t smoke. She was rushed into an operating room for an emergency cesarean. Stephen Robson, French’s obstetrician, smelled smoke in the operating room that night and realized that the pollution from the fires had penetrated through to the very center of the hospital, into the rooms that doctors are trained to keep sterile at all costs. French’s daughter, Margot, was born nearly five weeks early and underweight. It wasn’t until later that French began to wonder whether her placental abruption had anything to do with the bushfires surrounding Canberra. She was never told that the smoke might affect the timing of her birth or the health of her baby. She was never given a mask to use. As the summer continued and the fires only got worse, French began to notice the smoke in her home as she cared for Margot. She could see blue bands swirling beneath the overhead lights in her house. And even when she couldn’t see it, the stench was always there. Margot’s birth wasn’t the only abnormal delivery Robson witnessed that summer. He remembers seeing smoke floating in the beam of light cast by an overhead medical spotlight during what was otherwise a routine birth. ‘It looked like the bat signal,’ he said. ‘It was truly extraordinary.’ It’s not just the placental abruption that bothers French now, six years later. She had two more children in the years after giving birth to Margot, none of whom endured the kind of bushfire season her firstborn weathered in utero in 2019. Margot is the only one of the three who struggles with asthma, a chronic, non-curable respiratory disease that afflicts neither French nor her husband, and eczema, an itchy and recurrent skin condition. Many of the children born to French’s friend group during the Black Summer have also developed asthma and eczema. ‘Her early months of life were in the Black Summer, and I worry about that for her as she grows,’ she said. Anneke French sits with her daughter Margot. French worries that early-life smoke exposure may have contributed to some of Margot’s health conditions, like asthma. Jess Davis / ABC News The evidence connecting chronic conditions suffered by babies born during the Black Summer to the smoke their mothers inhaled is largely anecdotal. That’s part of the problem; the scale of smoke exposure in recent years is unprecedented, so evidence-gathering is still in relatively early stages. But treating the harms of wildfire smoke as an open question is less about waiting for the science to settle, and more about ignoring what we already know about the risks of very similar pollution. In other words, not preparing for wildfire smoke is a policy choice. General air pollution from trucks, factories, and other industrial sources is one of the most extensively studied environmental health risks in the world. It’s been the subject of sustained scientific inquiry since the 1970s, when governments began regulating and measuring air pollutants like sulfur dioxide, nitrogen dioxide, and carbon monoxide. This research shows that fine particulate matter seeps deep into the lungs and circulates through the bloodstream, touching nearly every organ system in the body. The resulting inflammation, clotting, and blood vessel damage is linked to coronary heart disease and a higher risk of stroke and heart attacks in adults. Lungs chronically exposed to air pollution are more likely to develop cancer. Brains show signs of neuroinflammation, cognitive decline, and dementia. Immune systems are more fragile and susceptible to disease. In total, the World Health Organization estimates that indoor and outdoor air pollution from all sources combined kills some 7 million people every year — more than the number of people who die from diabetes, tuberculosis, and in car accidents combined. In pregnancy, fine particulate matter is particularly damaging. A baby developing in the womb is uniquely vulnerable to disruption. Every organ in the body is rapidly developing. The health of the person carrying the baby is closely connected to narrow developmental windows; reduced lung function in the mother, for example, can restrict the flow of oxygen that’s crucial to brain development and overall growth. Studies show that particles in polluted air can enter the bloodstream and migrate across the placenta and even into placental tissue, where they disrupt oxygen and nutrient exchange with the fetus. Across large epidemiological studies, higher exposure to general air pollution has been consistently associated with increased risks of preterm birth, low birth weight, and stunted fetal growth — outcomes that already affect millions of pregnancies worldwide each year. ‘The exposures in utero, during gestation periods, have an impact on life and the development of children when they’re born,’ said Sotiris Vardoulakis, director of the Health Research Institute at the University of Canberra. ‘It can have consequences for many years — the rest of their lives.’ Sotiris Vardoulakis, director of the Health Research Institute at the University of Canberra, holds an air quality monitor in his office. While fire never touched central Canberra itself, the city endured some of the most prolonged and suffocating air pollution in the country, at times registering the worst urban air pollution in the world. Any air quality reading above 300 is considered hazardous, the index’s highest category of warning. Canberra’s reading exceeded 5,000 on New Year’s Day 2020. Jess Davis / ABC News There is some early evidence that wildfire smoke — which also contains fine particular matter — carries similar risks for babies and their mothers. A 2024 study that looked at a large cohort of births in the southwestern U.S. found that particulate matter from wildfires was linked to higher risk of preterm birth and low birth weight. An Australian cohort study of pregnant asthmatic women found that exposure to bushfire smoke was associated with asthma in their babies. Two studies published this year using large sample sizes provided by hospital systems in California found a novel connection between wildfire smoke and autism diagnoses in children exposed in utero. Examining the health consequences of breathing in wildfire smoke remains, however, a nascent area of scientific study — largely because, until recently, wildfire smoke was viewed as a periodic byproduct of disaster rather than a chronic public health threat that could match the scale of other sources of pollution. In the U.S., for example, wildfire smoke is still treated differently than other sources of air pollution by the Clean Air Act, and the Environmental Protection Agency considers pollution from wildfires as natural ‘exceptional events.’ The agencies tasked with air quality protection in other countries, including Australia, largely view the issue similarly. But the research landscape is changing as global warming lengthens the frequency and intensity of fire weather and wildfire smoke starts to affect more people. Exposure to wildfire smoke, while variable year to year, is trending upward in the U.S., Australia, Indonesia, Brazil, Europe, Russia, Canada, and parts of South Africa, among other places. In the U.S., smoke from wildfires has contributed up to a quarter of the total particulate matter pollution nationwide in some recent years, unraveling the air quality gains the country has made since 2000. Some research indicates that wildfire smoke might be more damaging than general air pollution — up to 10 times more harmful than the compounds in car exhaust, according to one study. Luke Wright takes a rest after putting out spot fires at his brother’s home near Sydney in December 2019. ABC News Emergency department records in areas affected by fires show that these intense episodes have the same consequences as background air pollution, but on shorter timescales. They boost hospitalizations for respiratory stress and cardiovascular conditions, and cause premature death. More than 400 people died from indirect smoke inhalation during the Black Summer, and several thousand more were hospitalized. Asthma-related emergency department visits across New York state spiked 82 percent at the peak intensity of the Canadian wildfire smoke event in 2023. Emergency room visits for heart attack symptoms rose 46 percent in the three months following the Los Angeles wildfires. The problem is set to get worse as the world moves deeper into the 21st century. Already, particulate matter from forest, grass, and peat fires kills an estimated 339,000 people a year worldwide. And climate-driven wildfire conditions are expanding across Australia, South America, Europe, and boreal Asia. A recent analysis found that millions of people at the edges of Australia’s biggest cities could experience urban wildfires similar to the devastating blazes that beset Los Angeles in the winter of 2025. The Black Summer was a golden opportunity to extract valuable information about the health effects of wildfire smoke on major population centers, but Australia’s government at the time appeared more interested in downplaying the severity of the crisis. ‘We’ve had fires in Australia since time began,’ Deputy Prime Minister Michael McCormack, leader of the right-wing National Party of Australia, said as the fires burned in 2019, calling the push to study the role climate change may have played in fueling the blazes the ‘the ravings of some pure, enlightened, and woke capital city greenies.’ The federal government ultimately committed just 5 million Australian dollars for bushfire-related health research across nine projects: AU$3 million for smoke exposure, and AU$2 million for the mental health consequences of the event. The sum was only enough to scratch the surface of the work required to understand the full scope of the smoke’s effects. (A single large epidemiological study in the U.S. can cost $3 million alone.) The health ramifications of the Black Summer were quickly eclipsed by the COVID-19 pandemic, which struck as the fires were ebbing. The biological samples — blood, tissue, placental cells, and other clues that could have laid the groundwork for long-term analyses of the health consequences of smoke exposure — were never collected and studied. ‘Initially, we had grand plans of going and getting blood samples and doing respiratory tests,’ said Christopher Nolan, an endocrinologist in Canberra who conducted surveys of pregnant women in 2020 to assess the impact of the fires on maternal and fetal health. The onset of the pandemic complicated those plans, and Nolan never ended up getting funding at the scale necessary to collect samples. After a series of public meetings, the Australian Parliament published an interim report in 2020 concluding that ‘long‑term funding and research is needed to more definitively determine the impact of hazardous smoke exposure and inhalation on individuals and the community.’ ‘We had a missed opportunity in Australia to invest in [understanding] the long-term consequences,’ said Arnagretta Hunter, a cardiologist based in Canberra who is part of Doctors for the Environment Australia, a network of medical professionals that advocates for climate action. Robson, the obstetrician who was working at Canberra Hospital during the Black Summer, feels similarly. ‘When babies were born, I noticed many of the placentas had changes that often you only see in severe disease, like severe blood pressure, or women with immunological diseases,’ he said. ‘It was striking and it occurred for months afterwards, because I presume women had been affected by the smoke when it was there and it played out across the rest of the pregnancy for them.’ Stephen Robson worked as an obstetrician at Canberra Hospital during Australia’s Black Summer wildfires. Jess Davis / ABC News Both Hunter and Robson say they fear Australia’s capacity to respond to smoke events hasn’t improved since. Robson envisions a protected area inside the country’s hospitals that can keep smoke out — a sort of citadel deep inside medical facilities where surgeons and other specialists can do their work without fear of smoke creeping in. Hunter would like placentas and other biological samples that may have been preserved in hospital freezers from that time to be thawed and studied. But the institutional will to take that on hasn’t materialized. ‘I don’t think we’re any better prepared to deal with an environmental catastrophe like this than we were the last time around,’ Robson said. Arnagretta Hunter, a cardiologist based in Canberra, looks at lung scans. Jess Davis / ABC News Even in the U.S., the country that produced the bedrock research on fine particulate matter underpinning global air quality standards, the dynamics of fire are changing so quickly that parents are still being left in the dark. Irene Farr could hear cars exploding somewhere in the distance on the night of January 7, 2025, near her house in northern Pasadena, California. When she poked her head out of her front door, she smelled thick smoke in the air. There was a red glow in the sky around Eaton Canyon, a nature preserve a few miles to the east. Farr thought she might get an alert telling her to evacuate or see fire trucks racing down her street. But the neighborhood was eerily quiet. Her neighbors were indoors. It seemed like just another night in Pasadena. Reddit, the social media site, told a different story. People were putting pins on a live map that showed where flames were erupting. Every time Farr checked the map, the pins were closer to her house. At 3 a.m., she reached her breaking point. She roused her daughter, Azul, and rallied her husband, David, and his parents, who live on the same property. They drove to David’s brother’s house half an hour away and stayed awake the rest of the night, wired and anxious for news about their neighborhood. The sun never rose that morning; the smoke was so thick that 6 a.m. looked like midnight. Smokes and flames overwhelm a commercial area during the Eaton Fire near Altadena, California, on January 8, 2025. Josh Edelson / AFP via Getty Images The Eaton Fire, one of two devastating wildfires that struck the Los Angeles area that January, ultimately killed 19 people and destroyed 9,000 buildings. Most of the deaths occurred west of a prominent north-south thoroughfare called Lake Avenue, where Farr’s house is located. Evacuation orders from the city arrived late — hours after residents on the east side of Lake Avenue had been told to leave. The Farr’s house was spared, but more than a year later the family still hasn’t moved back home. Azul was just 11 months old when the fires broke out — too young, Irene figured, to risk her being exposed to whatever the fires left behind. Schools, hospital clinics, supermarkets, warehouses, appliances, and plastics had been burned to ash. People online were saying that the affected areas would be toxic for at least a year. ‘We decided that we would wait until we had more data and information,’ Farr said. ‘What ended up being a two-week wait ended up being a one-month wait, ended up being a three-month wait …’ Whenever she went back to check on the old house, Farr felt a burning in the back of her throat, a ‘bubbling up.’ There was something lingering in the air, she thought, but she didn’t know what it was. Irene Farr holds her daughter Azul. They evacuated their home during the Eaton Fire in January 2025. Zoya Teirstein / Grist Frankly, no one knew — not even local air pollution researchers who have spent years studying the health dangers of wildfire smoke in the American West. ‘It was unprecedented,’ said Yifang Zhu, an air pollution researcher at the University of California, Los Angeles. Air monitoring stations across the country installed by the federal government are often designed to monitor general air quality. They take measurements every few days, data that helps states determine whether they are compliant with federal regulations. When the fires broke out, stations in Los Angeles continued to collect routine data on urban air pollutants, but the sensors weren’t equipped to capture the novel mix of compounds produced by burning cars, buildings, and asphalt. Many of the sensors were themselves lost to the fires. ‘One big lesson we learned is if something gets burned that’s not a traditional wildfire compound, if you don’t specifically look for it, you’re not going to find it,’ Zhu said. ‘It’s as if it didn’t exist.’ The problem is that designing and deploying air quality monitors that can capture the heady mix of pollutants released by urban wildfires is expensive and requires a lot of technical expertise. Yifang Zhu is an air pollution researcher at the University of California, Los Angeles. Zoya Teirstein / Grist Zhu’s colleague Mike Kleeman, an air pollution researcher at the University of California, Davis, drove around the Los Angeles burn zone in April last year, when cleanup crews were hauling away material, and took air samples with an expensive specialized air sampling instrument. He was looking for hexavalent chromium, a very toxic form of chromium used in industrial welding and manufacturing that’s linked to lung cancer. Air monitoring stations, and even air pollution research laboratories like Zhu’s, don’t measure the toxin because it requires unique equipment and it’s unstable, meaning you only have a short while to get it to the lab before it disappears. Kleeman found hexavalent chromium in the samples he collected at levels that were 200 times higher than they would be on a normal day in the city — not high enough to warrant a public health emergency, but illuminating for air pollution researchers who quickly realized that these urban blazes had introduced a new set of unknown variables. ‘We are facing an entirely new challenge when wildfires burn into major cities,’ Kleeman said. Zhu and Kleeman are members of the Los Angeles Fire Human Exposure and Long-Term Health Study, a collaboration between eight universities across the U.S. aimed at studying the short- and long-term health effects of the Los Angeles fires. The collaboration, funded by the Spiegel Family Fund, a philanthropic foundation formed by the creator of Snapchat, collected some of the biological data that researchers in Australia largely couldn’t obtain during and after the Black Summer. An initial study found peculiar trends in sodium and protein levels in the blood of people affected by the fires, an outcome experts still don’t understand. More research on those abnormalities and other findings is coming. Researchers involved in the initiative were focused initially on measuring the contaminants the fires produced and recruiting cohorts of people to study. Now, they’re turning to the work of investigating the long-term health impacts of the fires on those people, including subgroups like first responders and pregnant women. More in this series In Arizona, a fight against a deadly fungus is under threat from Trump’s health policies As aid dries up in Kenya, millions are threatened by the climate-driven disease kala-azar Rising heat, failing kidneys: Climate’s hidden toll on migrant workers In Bangladesh, thousands of volunteers are battling climate-fueled disease at its source A hotter, wetter South is becoming a breeding ground for mold The frantic, high-tech fight to stop climate-fueled dengue fever But the funding that rolled in from ultra-wealthy Los Angeles philanthropists in the immediate aftermath of the fires is starting to dry up. The federal government, beyond failing to fill the void, is cutting resources needed to understand the conditions that fuel wildfires in the first place. In April, the Trump administration announced a reorganization plan that includes closing 57 of 77 Forest Service research stations across the country, many of which study fire risk. There’s not much more momentum in Australia. Despite a change in government in 2022, no new major federal funding has been earmarked for bushfire smoke exposure research since the Black Summer, perhaps in part because a smoke event of that scale hasn’t happened since. As countries around the globe begin to grapple with the health consequences of smoke exposure, tens of millions of data points are entering the public record. But the way researchers in different countries conduct research — even the way scientists define the term ‘smoke exposure’ — is highly variable. Some scientists use satellites to study smoke exposure, while others use computer modeling. For pregnant populations, some scientists choose to analyze smoke exposure by trimester, others look at the total number of ‘fire days’ pregnant women live through. Efforts to identify long-term health trends are often scrambled by this lack of standardization, delaying the kind of unequivocal findings that prompt hospitals and governments to quickly implement new policies. The American and Australian co-authors of a 2024 global meta analysis of the research on wildfire smoke exposure in pregnant women found just 31 studies of a high enough caliber to include in their review. Their analysis was inconclusive because the studies, conducted in various countries with different methods, couldn’t be appropriately compared. In the end, the authors were forced to conclude that they had found ‘suggestive evidence of harm from exposure to wildfire smoke during pregnancy’ and that more research was needed. Nolan, the Australian endocrinologist, thinks there should be a scientific protocol that experts all over the globe use as they conduct research on the effects of smoke exposure on natal health. A universal standard that harmonizes datasets would allow researchers to share data between institutions and hone in on the biggest risks more quickly. ‘[When] different groups around the world collect the data the same way, well, then you get statistical power,’ Nolan said. Epidemiological standardization is what formed the basis of general air pollution regulations. The World Health Organization created global air quality guidelines in 1987 and established a benchmark for particulate matter pollution in 2005. Researchers were then able to draw concrete conclusions: A 2015 study, for example, found that for every 10 micrograms per cubic meter increase in fine particulate pollution, all-cause mortality rises by 4 percent. We know that wildfire smoke is bad for pregnant women. But answers to more specific questions — should women evacuate when particulate matter reaches a certain threshold? How many days of smoke exposure meaningfully increase the risk of preterm birth? — are still out of reach Read Next An early-life wildfire exposure sickened these monkeys for decades Jesse Nichols It’s not a matter of if the fires will come again, but when. Much of the American West just had one of its warmest winters on record. More than half the region is in a drought at a time of year when snowpack should have hit its peak, priming the landscape for fire. ‘We are facing a very challenging fire year,’ Mike Morgan, director of the Colorado Division of Fire Prevention and Control, said in April. ‘Our resources will be tested not only in Colorado, but across the West.’ Earlier this year, southeastern Australia experienced the most intense heat wave it has seen since the Black Summer — an event made five times more likely by climate change. The heat fueled a spate of bushfires across the state of Victoria that burned hundreds of homes and killed one person and thousands of livestock. In Canberra, where temperatures approached 110 degrees F, the smell of smoke from prescribed burning this fall brought French back to 2019. ‘As soon as you see that plume of smoke or smell it on the air, you want to know: Where? How close? Is it in control? Is it accidental?’ she said. French can find the answers to those questions on the Australian Capital Territory Parks website. But there is nowhere she can go for resolution about the long-term effects of the Black Summer on Margot’s health. ‘I don’t know how that will affect her,’ she said. ‘I still don’t know.’ This story was originally published by Grist with the headline Wildfire smoke engulfed their cities. Did it make their babies sick? on May 28, 2026.