The Toxic Mysteries of Wildfire Smoke

Despite presumably being an issue for the 300,000-plus years that humans have existed, we still know surprisingly little about wildfire smoke. As Eric Levitz writes at New York, the costs of wildfire smoke “are vast, and often undercounted” as they “extend beyond their direct medical impacts, as people lose time, money, and quality of life” to avoid the toxic haze.

With smoke from Canadian wildfires wafting over the United States once again, it’s becoming increasingly obvious that we need to unravel these mysteries. That’s where academics step in.

The work begins with what we know about pollution. For decades, researchers such as atmospheric scientists, public health scholars and economists have tried to understand the emissions that result from industrial activity. That work has given us tools to understand its impacts: The Air Quality Life Index “converts air pollution concentrations into their impact on life expectancy,” the OECD has taken aim at measuring its direct economic costs, and a Google Scholar search for “air pollution” yields 3,100,000 results.

But what we know about air pollution largely comes from research on the impacts of pollutants from human-created emissions like industry and transportation, said Joseph Shapiro, an environmental economist at U.C. Berkeley. Wildfire pollution has a different — and possibly more harmful — composition. And while industrial pollution is somewhat predictable, knowing when and where the next wildfire will begin is more challenging.

“There’s a lot more work that can be done,” Kenneth Gillingham, an economics professor at Yale, told me, despite there being a “whole suite of amazing scholars.” A Google Scholar search turns up 239,000 results for “wildfires” — and just 10,800 for “wildfire smoke.”

First, experts explained to me that we don’t have a well-rounded understanding of the smoke in economic terms, such as its total cost. But there are also many smaller but still vital pieces of the puzzle missing, such as a cost-benefit analysis of controlled burns, the best ways to protect indoor air quality, day-to-day microeconomic changes created by smoke, or the full extent of the disparities that exist in who experiences the worst of the smoke.

Many of these questions are at the intersection of environmental science and other disciplines. Gillingham, for instance, made the case that economists have the tools necessary to put numbers against these seemingly “intractable problems.”

“Until you put numbers to it, it’s hard to move opinion or policymakers,” Gillingham told me. “Economists are very adept at building the modeled framework … in thinking through the tradeoffs,” especially those “involved in different approaches to mitigating or adapting to climate change.”

One cost-benefit analysis that could offer immediate help is expanding the literature on the impacts of controlled burns, Shapiro said.

“Suppression has had lots of downsides,” he noted. “It’s just a matter of trying to make (wildfires) a more regular, natural process.”

A 2021 paper about wildfire risk in the U.S. raises this question directly: “Existing evidence does not provide a comprehensive understanding of how a given prescribed burning intervention … will change the timing, amount, and spatial distribution of smoke.” In other words: Controlled burns could be a salve for wildfire prevention, but we don’t know enough about their impacts to make them more widespread in public policy.

Another kind of research will help spell out the impacts of wildfires to the public — creating numbers and measures that can tell us their true costs.

The Air Quality Life Index, created by the University of Chicago’s Energy Policy Institute at Chicago, already offers one of those metrics. The map it produces at the intersection of economics, physical sciences, and public health is striking: Red hotspots show how many years of life an average person would gain if a country or province met WHO guidelines for PM2.5 pollution, particles smaller than 2.5 micrometers that pose health risks when inhaled.

The same metrics can expand to incorporate wildfire smoke: AQLI’s report has started to estimate the amount of life expectancy lost in a wildfire season (though it didn’t draw a causal connection between the wildfires and the life expectancy lost), said Christa Hasenkopf, director of AQLI — and internal discussions are considering how the index could further incorporate wildfires. Separately, a paper in The Lancet Planetary Health estimates that more than 33,000 people die annually due to PM2.5 released in wildfires.

An “amazing paper” could also bring together the full economic costs of wildfires — which are poorly accounted for already, as Marshall Burke has pointed out to Heatmap. That paper will do the most good if it serves as something of a collaborative aggregation, pulling together work on adaptation, environmental models, health, consumer behavior and other studies, Gillingham thinks.

Gillingham is especially interested in research that looks at the most micro-level impacts: Day-to-day consumer preferences and economic impacts that are visible as a result of smoky days. “What type of behavior changes do you see people making on the spot?” Gillingham wonders. Will air filter sales jump, or will PurpleAir units fly off shelves? If consumers don’t go outdoors, what will that mean for economic activity?

Hasenkopf, an atmospheric scientist by training, also thinks that a better understanding of how to protect the air quality of indoor public spaces, such as schools, will prove important in adapting to smoke.

Inequity underscores the broader conversation about air pollution: Hasenkopf is quick to point out the comparison between “the rightful reaction (to smoke) on the East Coast compared to the daily toll that air pollution is having in other places across the world.” Funding for air pollution research is limited, and parts of the world, the U.S. included, suffer from a “huge data monitoring issue.”

But the study of air pollution in America has also been one of the unequal nature of exposure to pollution. Gillingham, for instance, has written a paper about racial disparities in pollution from ports.

He wants to know if wildfire smoke has “disparate impacts, or is it hitting everyone?”

“In many cases, wildfire pollution just hits everyone.” Which, of course, is true: No New Yorker was exempt from the sepia-toned skies of early June, and every Chicagoan stepped into the same smoky air this week.

But just as there were inequalities baked into the COVID-19 pandemic, smoke hits different segments of society harder than others Early research, for instance, already shows that white, higher-income populations are more likely to be able to travel away from smoky conditions. Communities of color are at higher risk of asthma and other medical conditions easily exacerbated by smoke, to say nothing of the air purifiers and newer buildings with better HVAC systems that are more easily available to people in higher income brackets.

If numbers do move the political conversation and inform policy, the incentive to step up research — fast — is strong. Smoky days are looking like a months-long phenomenon across the country. It’s not enough to know if recess should be outside on a given day, we need to talk about improving the air students breathe indoors, too. It’s no longer a conversation that can be isolated to just one region, just as it never has been isolated to just one field.