March 2020, ScientificAmerican.com 41improve the accuracy of wildfire-emissions forecasts, so that
coaches know better when to cancel soccer practice, hospitals can
anticipate an influx of immunocompromised people and regula-
tors can protect outdoor workers from dangerous exposure. Their
data could also help land managers light controlled burns, which
mitigate the severity and health impacts of future wildfires.
Crawford checked his tablet, scrolling through real-time
updates of the hundreds of particles and gases being sampled.
The last time he had flown in the DC-8 was to study urban pollut-
ants in Seoul, South Korea. Even in small cities, he said, research-
ers see pollution that is much worse than what he and his team
were witnessing that day. “But how do all these fires add up?” he
asked. “How much ozone do fires produce? What’s the chemistry
for how it forms? And how do you regulate a natural phenome-
non?” Carsten Warneke, a fellow principal investigator of FIREX-
AQ, who is based out of Noaa’s Earth Systems Research Laborato-
ry in Boulder, Colo., explains that air-quality models treat wildfire
smoke as a smog event when it is a completely different problem.
Some 350 miles to the south, on the Gowen Field Air National
Guard Base in Boise, Idaho, Warneke and 50 more scientists were
sifting through meteorological patterns, fuels, real-time satellite
data and ongoing fire updates to determine which of the West’s
wildfires met the most criteria for FIREX-AQ’s goals. “There are alot of scientists, and they all want slightly different things,” said
Amber Soja, an associate research fellow at the National Institute
of Aerospace, who was responsible for briefing the 400 research-
ers involved in FIREX-AQ on that day’s fire activity.
For today’s mission, the team had picked the North Hills Fire
in Montana as the DC-8 taxied onto the runway for takeoff. It had
the most pronounced smoke column of the nine fires being con-
sidered. At a relatively small 4,600 acres, the blaze was wholly
unremarkable—and that is what made it scientifically alluring.
Although U.S. Forest Service firefighters were still working to con-
trol the flames, they granted the DC-8 permission to sample the
plume at different points in time and space, thereby capturing
what was in the smoke and how it changed as it moved downwind,
interacting with new conditions and environments.
After passing through the plume for the 16th time in an hour,
Crawford received a message from Warneke at mission command.
It contained a satellite image of a smoke column shooting above
the clouds just below California’s Mount Shasta, almost 800 miles
to the southwest. Warneke had drawn a circle around the plume
and scrawled next to it in red ink, “GO HERE NOW!”AN UNPRECEDENTED PROJECT
FiREX-aQ, or Fire Influence on Regional to Global Environments
and Air Qualilty, was born in Montana’s Fire Lab. There Noaa re -
search chemist Jim Roberts, who was part of the team that devel-
oped a technique for measuring atmospheric nitrogen during the
ozone crisis of the 1970s, had grown interested in investigating
the acids present in wildfire smoke. In 2009, while burning pon-
derosa pine branches and other fuel characteristic of the Western
U.S., he found a particularly noxious com pound called isocyanic
acid. Regular exposure in hu mans, from sources such as ciga-
rettes and cooking fires, can cause cataracts, rheumatoid arthritis
and heart disease. Soon after, Roberts was in his office in Boulder,
Colo., when the most destructive wildfire in the state’s history
broke out, burning tens of thousands of acres and destroying sev-
eral hundred homes on the town’s outskirts.
Curious about whether his lab findings would hold up in the
real world, Roberts dragged out an instrument that measures
acids to test Boulder’s air. He found the highest concentration of
isocyanic acid ever measured in the atmosphere. Before that, no
one had thought to look for it. “I didn’t sleep for two nights,” he
says. “The biomass-burning community was completely unaware
isocyanic acid was in smoke. What else didn’t we know?”
Generally speaking, air quality in U.S. cities has improved
greatly since Congress passed the Clean Air Act in 1970. But when
wildfires burn near urban areas, smoke undoes those gains. In
2019 the top eight most polluted cities in America by measure of
ozone were all in the West. By measure of PM 2.5 —particulate
matter smaller than 2.5 microns that can embed in human lungs
and enter the bloodstream—23 of the top 25 cities were in the
West or Alaska. That trend is all but certain to hold: the Forest Ser-
vice now anticipates a doubling of annual acreage burned by 2050.
Chief among the culprits for this problem is climate change:
the West is becoming warmer and drier. In July 2019 climate
modeler Park Williams of Columbia University published find-
ings in the journal Earth’s Future showing that California’s five-
fold increase in acreage burned between 1972 and 2018 was very
likely linked to a 1.4-degree Celsius increase in hot-day tempera-
tures. Anthropogenic warming, he says, is to blame.LICK CREEK FIRE in Idaho
is one of the Western wildfires
FIREX-AQ chose to investigate
on August 2, 2019.© 2020 Scientific American © 2020 Scientific American