There’s no escape from wildfire smoke
In Western Canada, fire season comes early by American standards — beginning, usually, right around now. In Alberta, by today’s date, only about 1,000 acres have burned in recent years. This season so far, the total is already more than 1.5 million — which would make it the province’s third-worst annual result, just a few weeks into May, with months more of wildfire season still to burn. In the United States, by contrast, those who live in fear of wildfire are probably breathing a bit easier. Last year was a relatively light one, with fewer than eight million acres burning across the country — close to the two-decade average and well below the damage of several especially scarring recent seasons. This year looks potentially even milder, thanks to the onslaught of “atmospheric rivers” along the West Coast, which many Californians experienced as extreme weather whiplash but which also supercharged the state’s depleted snowpack, turned millions of drought-browned acres a verdant green and at least for a time managed to substitute the fear of flooding, in California’s quasi-apocalyptic ecological imagination, for fear of fire. For now there may be out-of-control blazes burning in Alberta, 2,000 miles away, but to most on the American side of the border, they are out of sight and out of mind. But a new lesson from the evolving science of wildfire is about how far its toxic smoke spreads and how widely its noxious impacts are distributed. You may think of fire in terms of scorched homes and go bags sitting ready for sudden evacuation. But distance is no cordon sanitaire for smoke. In fact, according to one not-yet-published study led by Stanford researchers exploring the distribution of wildfire smoke, an estimated 60 percent of the smoke impact of American wildfire is experienced by those living outside the states where the trees are in flames. Eighty-seven percent of the impact is experienced by those living outside the county of the original fire. And the problem is getting much worse. In recent years, a new generation of California fires have taught us their own new vocabulary: “gigafires,” for fires burning a million or more acres; “fire tornadoes,” for blazes burning intensely enough to create their own dramatic weather systems; the “pyrocene age,” for the current global era defined by fires. Perhaps more memorably, we are now haunted by a new visual vocabulary, too: a town called Paradise incinerated in hours, amber urban skyscapes and whole cities navigating darkness at noon, dashcam evacuations through walls of flame. And the fires have indeed been off-the-charts, with every single one of the 15 largest in modern California history taking place in the past two decades. Six of the seven biggest have occurred since 2020. According to CalFire, a quarter of Californians now live in zones at high risk of fire. And thanks in part to the state’s perverse housing policy, those building new homes and communities are even more likely to live in the future path of flames: According to one measure, more than 60 percent of new development in California since 1990 has been in wildfire-prone areas. But while Americans often think of wildfires as a California problem, it’s much bigger than that, with more burning elsewhere in the country every year. By some estimates, land burned across the American West grew ninefold between 1984 and 2015. It may increase several more times over in the decades ahead. The number of people exposed to what are sometimes called extreme exposure days — when particulate matter is about seven times as high as the World Health Organization safety standard — has grown 27-fold in just the last decade. In recent years, wildfire smoke accounted for up to half of all air pollution in the American West — meaning that if you live there, as much particulate matter has blown into your skies and your lungs from the burning of trees and brush as from all other human and industrial activity combined. And the grim effects are not locally constrained: Approximately half of American deaths from all forms of air pollution come from out-of-state sources, according to one study published in Nature in 2020 — a finding that implies a remarkably large toll, given that estimates for the total number of premature American deaths attributable to fossil fuel pollution in a given year run as high as 350,000. This is not just a matter of wildfire plumes of particulate matter straddling a nearby state line. According to a 2021 study published in GeoHealth, in recent years, wildfire smoke has caused more harm to the health of Americans living east of the Rockies than to those living west of them. Indeed, the researchers found that on average, between 2006 and 2018, three-quarters of the mortality impact from wildfire smoke was experienced outside the West. (The result reflects the different population densities in each area, among other non-fire factors.) In recent years, many have drawn an intuitive contrast between the visible menace of air pollution and the sometimes-harder-to-perceive threats from climate change: While global warming distributes its brutality over time and around the world — in that way distending or obscuring chains of responsibility — the effects of air pollution are far more concentrated locally, putting theoretical authority over the problem in the hands of those who see its effects most directly. I’ve written a few pieces making that point myself, and suggested that more emphasis on air pollution might help “solve” some of the rhetorical challenges of climate activism. But the more we learn, the less true this seems. Between 2006 and 2010, the authors of the Stanford preprint found, there were hardly any places across the American West where wildfire smoke from other counties contributed even 10 percent of air pollution. Between 2016 and 2020, by contrast, such smoke was contributing as much as half the air pollution to huge swaths of the region. Already, wildfire pollution has undone large chunks of the air quality gains produced by the Clean Air Act. In decades to come, it will become the dominant source of particulate pollution in the United States. This is not to say that there isn’t substantial local risk from smoke exposure: According to one large study published last year in The Lancet Planetary Health, anyone living within approximately 30 miles of just a single wildfire was, over the course of about 20 years, almost 5 percent more likely to develop lung cancer and 10 percent more likely to develop brain tumors. And beyond cancer, the list of health impacts linked to particulate pollution grows seemingly by the day: respiratory disease and cardiac disease, Alzheimer’s disease and Parkinson’s disease, dementia, mental illness and suicide, cognitive performance and memory issues, miscarriage and premature birth and low birth weight. Recent research suggests that, of all forms of particulate pollution, wildfire smoke may be the most toxic. And given the way it is discharged upward into the jet streams of the lower atmosphere, it may travel much further to find its way into your lungs, too. Already the smoke from Alberta, blanketing much of Western Canada in satellite imagery and darkening Calgary’s midday skies to a dull, muddy orange, is pushing down into the U.S. Midwest and toward the Eastern Seaboard — where Americans live densely, most of them believing that wildfire smoke is a remote hazard limited to the rugged West. 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