Most scientists’ labs don’t fly. Most scientists’ labs are also not packed in the interior of a DC-8 jet doing loopy manoeuvres at low altitudes. This joint mission carried out by NASA and the US National Oceanic and Atmospheric Administration (NOAA), though, is not a typical science lab. And it’s not doing typical experiments.
The FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) mission spent the summer flying planes through smoke plumes associated with wildfires and planned agricultural burns to understand how the air we breathe – and our health – is impacted by fire. This monumental research effort will eventually lead to better forecasts and alerts to communities downwind of serious smoke pollution.
The wildland-urban interface is where homes are in or near flammable vegetation. Structures here are frequently damaged in wildfires, putting people at risk of death or injury. From 1990 to 2010, the number of new houses in the wildland-urban interface in the US grew by 41 per cent from 30.8 million to 43.4 million. This encroachment of homes into wildlands and rising temperatures will likely not only lead to the continued loss of property and life but also exposure to smoke and the attendant health risks.
The Camp Fire in 2018, in the US state of California, had 85 fatalities – the deadliest wildfire in California history. At the time, smoke from that fire also created the most toxic air on the planet and left millions in California struggling. Last week, 200,000 people in California's Sonoma County were under evacuation orders from the Kincade Fire, which according to the Sonoma County Sheriff’s Office is the largest evacuation anyone can remember for the county. These fires vividly illustrate why FIREX-AQ results could be so valuable as more people move to areas that could be lit up by flames or clogged with smoke.
From July to September, FIREX-AQ sampled smoke and air quality in wildfires from a base in Boise, Idaho and then moved on to sampling prescribed agricultural burns in Salina, Kansas using a fully outfitted DC-8 laboratory. The massive team of researchers involved in this project measured a wide variety of smoke characteristics, like trace gases and tiny particles known as aerosols, as the plumes moved and evolved over time across the landscape.
The DC8 lifts off from Boise for another FIREX-AQ science flight on 13 August 2019. (Photo: Joseph Katich/NASA)
The flight procedure for sampling smoke from fires is quite dissimilar from a normal commercial flight path to put it lightly. This DC-8 didn’t always operate at normal cruising altitude or even fly in a straight line from point A to point B. To get the best sampling coverage, the pilots flew the plane in a line and then turned around to head back the way they came from again, almost like someone pushing a lawnmower to make nice neat lines in a field. When sampling agricultural burns, the pilots manoeuvred the DC-8 in a clover pattern that can be a bit nauseating.
Glenn Wolfe, a research assistant professor at the University of Maryland Baltimore County and NASA’s Goddard Space Flight Center, described it in frank terms: “Everybody throws up in a bag at some point.” To avoid the constant use of air sickness bags, the researchers generally medicated with Dramamine and scopolamine.
On any given flight, around 40 researchers and pilots were packed into the plane with their instruments for six to eight hours at a time. Flying through hot smoke plumes at 1,000 feet can be especially rough in a crowded cabin. The plane needed to fly at such low altitudes – your average commercial flight cruises above 30,000 feet – to capture certain smoke samples, especially while on the second half of the trip when they were sampling smaller prescribed agricultural fires. The lower the altitude, the hotter the plane gets, especially with all those instruments. When the skies are calm, though, there are some perks to doing science in a plane.
“It’s basically like sitting in the laboratory with a really nice view out the window,” said Rebecca Hornbrook, a project scientist in the VOC measurement group at the US National Center for Atmospheric Research.
The canisters filled with smoke from the FIREX-AQ mission are unpacked in the lab so they can be analysed in Boulder, Colorado (Photo: Jessica Gilman)
Numerous scientists were on the FIREX-AQ mission to measure components of smoke that impact health called volatile organic compounds (VOCs). Indoors, they are released from a range of human-made substances like paints, air fresheners and cleaners. Outdoors, smoke from burning biomass (like forests) and anthropogenic emissions contribute to VOCs in the global atmosphere. These compounds can cause health issues both indoors and outdoors. Exposures to VOCs can cause short term health issues like eye, nose, and throat irritation, and long-term exposure can cause organ damage and exacerbate conditions like asthma.
Once VOCs hit the atmosphere, they contribute to ozone formation. While it is good to have ozone in the stratosphere’s ozone layer to reduce the amount of incoming ultraviolet radiation from the sun, when ozone is at the planet’s surface, it is actually a pollutant. The DC-8 was set up to measure different VOCs, like formaldehyde and benzene, with a variety of different instruments, to better understand how biomass burning contributes to the presence of VOCs in the atmosphere.
Jessica Gilman, a research chemist in NOAA’s chemical sciences division, explained that different sampling methods reveal the complex characteristics of smoke. Her responsibility on the FIREX-AQ mission was collecting smoke samples to run on the ground in a machine called a gas chromatograph-mass spectrometer. Although it has a long name, the GC-MS is a “common kind of instrument,” Gilman said. “You even see it on TV, like CSI.” The GC-MS is used to analyse the amounts of specific types of VOCs in the smoke samples.
Gilman does her experiments back at the lab in Boulder, so while she was on the plane she deployed something called whole air samplers. When Gilman or another scientist pressed a button, these canisters opened up and filled with smoke. When the plane landed, the 72 canisters were off-loaded and shipped overnight via FedEx to Boulder, Colorado. Gilman said that between her group and another group sending samples to Irvine, California, they were loading and unloading “easily 1,000 pounds of equipment” every flight just for these experiments.
Rebecca Hornbrook, on the other hand, used a GC-MS that was physically on the plane for measuring VOCs straight out of the air and processed them immediately. Hornbrook used the trace organic gas analyser or TOGA, a machine that measured the amounts of VOCs in smoke as they flew through it.
“Usually, if you’re just in a lab a gas chromatograph takes about an hour to sample, but this instrument can basically take a sample and analyse it… the processing time is just about a minute and a half,” Hornbrook said.
Different sampling approaches are necessary to fully understand the complex composition of smoke, as fire emissions chemically evolve over time. Some types of VOCs in smoke are not around for long, so while the ground-based lab provides a more stable environment to do analyses in, Hornbrook said certain VOC measurements need to be made immediately on the plane.
A view from the front-facing camera on the plane helps the researchers know when to start sampling a smoke plume from a wildfire. (Photo: Jessica Gilman)
Figuring out where to fly to get the best samples was not always easy. Some scientists who are firmly on the ground, like Rebecca Buchholz, helped guide the flying lab. Buchholz is a project scientist at the National Center for Atmospheric Research who doesn’t measure chemicals in the smoke, but instead figures out where it will go hours, days, and weeks after a wildfire starts burning. She also helped pilots figure out where to fly the plane as the plumes evolved.
While the plane was sampling the smaller agricultural fires, the plane had a general flight path, but if Buchholz and the other scientists on the ground saw a hotspot elsewhere, they told the pilots who then got permission to change the flight path and head that way.
“And then we’re all biting our nails waiting for them to say ‘we see smoke’ and then when they say ‘we see smoke,’ we’re like ‘yes!’” she said.
This unique fire-only mission had been in the planning process for years, but it came at just the right time as fires in the Western US are getting more intense and destructive driven in part by rising temperatures. “As many people are moving out West, you have a higher population density at this urban-wildfire interface,” Gilman said.
The results from this summer’s mission are currently being processed, which will take years to complete, but some findings are already coming together according to the researchers. Buchholz and other smoke modellers will use the measurement data to improve fire emission models going forward. Wolfe measures formaldehyde that forms from fire emissions and will use the FIREX-AQ data to compare with formaldehyde measured from NASA satellites. The vast amount of measurements and statistics collected this summer will not only allow scientists to better understand the components and movement of the smoke but will provide data for interdisciplinary public health research.
Even though the scientists had to endure some air-sickness to collect the massive trove of data over the course of an entire summer, it was worth it in the end. “We’ve never had a mission that was just [sampling] fires,” Wolfe said. “Now we think we can really pin down what the emissions are and how they affect air quality.”
Shaena is a freelance science journalist based in Phoenix, Arizona. You can find her on Twitter.
Featured image: NASA Earth Observatory