Scientists race to reveal how surging wildfire smoke is affecting climate and health

Emily Fischer is likely one of the few people whose summer plans were buoyed by a recent forecast that much of the western United States faces another worse-than-normal wildfire season. Unusually warm weather and drought, together with plenty of dry grass and brush, are expected to create prime conditions for blazes this summer, federal officials announced on 10 May.

The forecast has local officials bracing for the worst. But it represents an opportunity for Fischer, an atmospheric scientist at Colorado State University in Fort Collins who is preparing to spend the summer flying through plumes of wildfire smoke aboard a C-130 cargo plane jammed full of scientific equipment. The flights are the highlight of an unprecedented effort, costing more than $30 million, that involves aircraft, satellites, instrumented vans, and even researchers traveling on foot. Over the next 2 years, two coordinated campaigns—one funded by the National Science Foundation (NSF), and the other by NASA and the National Oceanic and Atmospheric Administration (NOAA)—aim to better understand the chemistry and physics of wildfire smoke, as well as how it affects climate, air pollution, and human health.

"This is definitely the largest fire experiment that has ever happened," says atmospheric chemist Carsten Warneke of NOAA's Earth System Research Laboratory in Boulder, Colorado, one of the lead scientists. Wildfire smoke, he adds, is "one of the largest problems facing air quality and climate issues going forward."

The problem is growing as the size and intensity of wildfires rise in the western United States, marinating communities in smoke. Wildfires account for more than two-thirds of the particulate matter in the West on days that exceed federal clean air standards, according to a 2016 study in the journal Climatic Change. And global warming is likely to stoke even more fire in coming years, by making wildlands more combustible. By midcentury, more than 80 million people living across much of the West can expect a 57% increase in the number of "smoke waves"—events that shroud a community for 2 days or more—according to the 2016 study. The consequences for public health could be sobering; smoke includes an array of noxious compounds and tiny particles that can complicate breathing and promote disease. Other parts of the Americas as well as Europe, Africa, Asia, and Australia are likely to experience the same climate-driven surge in wildfires, according to U.S. Forest Service researchers.

Despite the potential threat, wildfire smoke has received little sustained scientific attention. The two new campaigns aim to change that. This year, the NSF-funded team that includes Fischer aims to fly its instrumented C-130 through 15 to 20 wildfire plumes. And next year, researchers with NASA and NOAA will have access to a bigger aircraft—a DC-8 jet—that will scour smoky skies across the United States.

One goal is to inventory the chemicals released by wildfires, including nitrogen oxides and carbon monoxide, and a vast array of volatile organic compounds. Current models for predicting the chemical makeup of smoke, which rely largely on satellite observations, have a huge margin for error, Warneke says. In part, that's because of uncertainty about how much vegetation wildfires consume. New studies that combine data from satellites, aircraft, and ground-based researchers scrutinizing burn sites should help fine-tune those estimates.

If wildfires are burning in the Pacific Northwest, what does that mean for Colorado … ? Emily Fischer, Colorado State University

Researchers will also use the C-130 to chase plumes during their first 24 hours aloft, to see how the chemistry of smoke changes as it wafts through the atmosphere. In particular, they hope to get a more precise picture of what happens to the nitrogen released by burned vegetation, including how much is converted into nitrogen oxides that can contribute to ground-level ozone, a regulated pollutant that can worsen breathing problems. Such data, Fischer says, could help answer questions like: "If wildfires are burning in the Pacific Northwest, what does that mean for Colorado air quality?"

Researchers also plan to track the evolution of aerosols—minute particles that can either scatter or absorb sunlight, and play a major role in shaping climate. And they want to observe plumes as they collide with clouds, to better understand how the two affect each other. Smoke particles can alter cloud formation by acting as nuclei for ice particles, potentially influencing the weather, and cloud moisture can alter smoke chemistry. The results could help improve weather forecasts.

At night, falling temperatures can cause smoke plumes to sink into valleys, worsening air quality there. NOAA and NASA researchers will track the plumes with aircraft, vans, and a drone. That initiative will also involve DC-8 flights beyond the West, into the Midwest and Southeast, tracking smoke from fires intentionally set to clear farm fields and prescribed burns in forests. The goal of collecting such a wide array of data, Warneke says, is "to do the whole picture at one time and understand how the whole thing plays together."

A smokier future Forecasts suggest the western United States will see more wildfire smoke waves (events lasting 2 days or more) and longer periods when smoke waves occur.

Beyond these projects, public health researchers are taking a growing interest in what happens when smoke blankets communities, sometimes for weeks at a time. Past studies have found that short-term smoke exposure can increase problems for people with asthma and other lung ailments, but "there's really not much information at all" about the effects of long-term, chronic exposure, says Curtis Noonan, an environmental epidemiologist at the University of Montana in Missoula.

Noonan was at the center of some of the worst smoke of the 2017 wildfire season, when Montana was hit by fires that burned 400,000 hectares. The biggest blow fell on Seeley Lake, a town of 1600 located 50 kilometers northeast of Missoula. The nearby Rice Ridge fire filled the town with smoke for much of August and early September 2017, driving levels of fine particulate matter to nearly 20 times the acceptable limit set by the Environmental Protection Agency.

Noonan is now working with colleagues to gather health information from residents of Seeley Lake and several other Montana towns. They aim to track how respiratory performance, mental states, and genetic markers related to inflammation change when smoke descends. Noonan is also seeking funding to sift through health records of wildland firefighters to understand how sustained smoke exposure has affected them.

Farther north, Sarah Henderson, an environmental epidemiologist and veteran smoke researcher at the British Columbia Centre for Disease Control in Vancouver, Canada, hopes to track the fate of children born during high-smoke events. One big question, she says, is: "If you're born into really smoky conditions with your extremely sensitive, newborn lungs, what does that mean for you?"

As scientists prepare to tackle such questions, health officials in Missoula are preparing for a possible repeat of last year's smoke waves. The health department is stockpiling indoor air filters for day care centers, schools, and other gathering spots.

Fischer, for one, hopes they aren't needed. Although she requires fire for her studies, she says, "I'm just wishing for an average wildfire year with wildfires in wilderness areas that don't cause any property damage."