Wildfire smoke already kills an estimated 40,000 annually, the same number that die in car crashes.
You may live many miles away from a wildfire, but it could still kill you. That’s because all that smoke wafting in from afar poses a mortal risk. The threat is so great, in fact, that any official tally of people killed in a fire most likely is wildly low, given that it counts obvious victims, not those who later died after inhaling its far-flung haze. Los Angeles’ catastrophic blazes in January, for instance, killed 30 people according to authorities, but more like 440 according to scientists, who determined excess deaths at the time were likely due to smoke.
As climate change makes such conflagrations ever more catastrophic, that mortality is only going to escalate. A new study in the journal Nature estimates that wildfire smoke already kills 40,000 Americans each year — the same number who die in traffic crashes — and that could rise to more than 71,000 annually by 2050 if emissions remain high. The economic damages in the United States may soar to over $600 billion each year by then, more than all other estimated climate impacts combined. And the problem is by no means isolated to North America: A separate paper also publishing today estimates that 1.4 million people worldwide could die prematurely each year from smoke by the end of this century — six times higher than current rates.
Together, the studies add to a growing body of evidence that wildfires are killing an extraordinary number of people — and are bound to claim ever more if humanity doesn’t rapidly slow climate change and better protect itself from pollution. “The numbers are really striking, but those don’t need to be inevitable,” said Minghao Qiu, an environmental scientist at Stony Brook University and lead author of the first paper. “There are a lot of things we could do to reduce this number.”
The core of the problem is desiccation: As the planet warms, the atmosphere gets thirstier, which means it sucks more moisture out of vegetation, turning it to tinder. Scientists are also finding more weather whiplash, in which stretches of extra wet conditions encourage the growth of plants, followed by stretches of extra dry conditions that parch all that biomass. Droughts, too, are getting worse, making landscapes exceptionally flammable.
Tragically enough, wildfires have grown so intense and deadly in recent years that scientists have been getting bountiful data to make these connections between the haze and cascading health problems downwind. “We totally underestimate the total burden when we don’t consider the smoke that is generated, that can be transported miles and miles away,” said Tarik Benmarhnia, a climate epidemiologist at the Scripps Institution of Oceanography, who studies the impacts of smoke but wasn’t involved in either of the new papers. “That is by far the biggest factor for mortality and other health issues associated with this type of pollution.”
Bigger, more intense infernos are belching smoke not just for days or weeks, but sometimes months at a time. This year’s blazes in Canada, for instance, have consistently blanketed parts of the U.S. in unhealthy air quality. That adds to the haze produced by domestic fires, especially in the West, making for dangerous conditions across the country. Indeed, Qiu’s modeling estimates that annual wildfire emissions from the Western U.S. could increase by up to 482 percent by 2055, compared to the average between 2011 and 2020.
In the global study published today, researchers estimate that worldwide, this deadly pollution could grow by nearly 25 percent by the end of the century. But it won’t be evenly distributed: Africa could see 11 times more fire-related deaths by that time, compared to Europe and the U.S. seeing one to two times as many. “Africa has the world’s largest burned area due to extensive savannas, forests, and grasslands, combined with long dry seasons,” said Bo Zheng, an associate professor at Tsinghua University in China and co-author of the paper, in an email to Grist. “This widespread burning drives disproportionate smoke exposure and health impacts.”
The major concern with wildfire smoke is PM 2.5, or particulate matter smaller than 2.5 millionths of a meter, which burrows deep into the lungs and crosses into the bloodstream. More and more research is showing this irritant is far more toxic than that from other sources, like industries and traffic. “We have mountains of evidence that inhaling these particles is really bad for a broad range of health outcomes,” said Marshall Burke, an environmental economist at Stanford University, who co-authored the paper with Qiu. “They’re small enough to sort of spread throughout your body and cause negative health impacts — respiratory impacts, cardiovascular impacts. Most, I would say, bodily systems now show responses to air pollution and small particle exposure.”
Making matters worse, wildfires aren’t just turning plants into particulates. Those Canadian conflagrations have been burning through mining regions, where soils are tainted with toxicants like arsenic and lead, potentially mobilizing those nasties into the atmosphere. And whenever fires burn through the built environment, they’re chewing through the many hazardous materials in buildings and vehicles. “It burns up cars, it burns up bicycles, it burns up anything that’s in your garage,” Burke said. “That’s incinerated, aerosolized, and then we’re literally breathing cars and bicycles when we are exposed to that smoke.”
All told, even brief exposures to wildfire smoke can be devastating, exacerbating respiratory conditions like asthma and chronic obstructive pulmonary disease, as well as cardiovascular diseases, since PM 2.5 is entering the bloodstream. Those issues can continue for years after exposure, and other toxins like carcinogens in the haze can cause still more problems that might last a lifetime.
Qiu and Burke’s new modeling estimates that cumulative deaths due to wildfire smoke in the U.S. could reach 1.9 million between 2026 and 2055. That’s a tragic loss of life, but it also comes at a major economic cost of lost productivity. And that doesn’t even include the impacts that are non-lethal, like the degradation of mental health and people missing school and work because of poor air quality.
There are ways to blunt this crisis, at least. Reducing carbon emissions will help slow the worsening of wildfires. Doing more controlled burns clears built-up fuel, meaning the landscape might still ignite, but less catastrophically. And governments can help their people get air purifiers to run during smoky days. “If climate change continues apace, but we reduce the amount of fuel loading in our forests and are better able to protect ourselves, then our projections are going to be overestimates of the damages, and that will be a good thing,” Burke said. “These damages are not inevitable.”