20 SCIENCE NEWS | June 18, 2022© 2014 KATHY WEST/CALIFORNIA NATIONAL PRIMATE RESEARCH CENTER/UC DAVISFEATURE | WILDFIRE SMOKE THREATENS HEALTH FROM AFAR
from a series of devastating wildfires in Northern
California. Researchers have been comparing those
monkeys with macaques born a year later that
weren’t exposed to smoke.
At around age 3, macaques exposed to smoke
displayed immune disorders and reduced lung
capacity, lung function and lung volume, says Hong
Ji, a molecular biologist at UC Davis and the primate
center who wasn’t involved with this study. The
lungs look like they had fibrosis, Ji says. “Early life
smoke exposure ... changed the trajectory of lung
development,” and it doesn’t appear to be revers-
ible, she says.
The monkeys exposed to wildfire PM2.5 also have
important changes to how their DNA works, Ji and
colleagues reported in the January Environment
International. Exposure to wildfire smoke in infancy
can cause life-altering, long-term changes to the
monkeys’ nervous and immune systems, as well as
brain development, Ji says. Even worse, she says,
the DNA changes are the type that can be passed
down and may result in generational damage.
Even macaques born after in utero exposure towildfire smoke can suffer cognitive, immune and
hormone problems, primate center researchers
reported April 1 in Nature Communications.
Now, Ji and colleagues have teamed with Rebecca
Schmidt, a molecular epidemiologist at UC Davis
who’s leading a study on the effects of wildfire smoke
exposure on pregnant women and young children.
This research group, as well as other teams, is
also looking into whether PM2.5 is causing genetic
changes to babies exposed to smoke in utero, Ji
says. The more results gathered on the effects of
wildfire PM2.5 on babies and children — and even
in pregnancy — the more dangerous we realize it
is, Ji says.Chemical differences
Particulate matter changes as it travels through the
atmosphere, both in volume and in chemistry. Some
PM2.5 is emitted directly from fires, and some is
born from chemicals and trace gases emitted from
fires that get chemically processed in the atmo-
sphere, Buchholz says. Reactions that happen in the
smoke plume, combined with sunlight, can create
even more PM2.5 downwind of the fires. How these
particulates change chemically — through interac-
tions between the atmosphere and the particulate
matter, and between fire pollution and human pol-
lution — and what that means for human health “is
a really active area of research right now,” she says.
“It’s super complicated.”
Epidemiological and atmospheric chemistry
studies indicate that wildfire PM2.5 is more haz-
ardous to human health than ambient PM2.5, says
Stowell, the Boston epidemiologist. One such study
compared particulate matter from Amazonian
fires with urban sources such as vehicle exhaust
in Atlanta. Nga Lee Ng, an atmospheric chemist at
Georgia Tech, and colleagues found that smoke
particulate matter is more toxic than urban par-
ticulate matter, “inducing about five times higher
cellular oxidative stress,” Ng says. Oxidative stress
damages cells and DNA in the body.
In addition, as smoke travels through the atmo-
sphere and ages, it seems to become even more
toxic, Ng says. Reactions between the particu-
late matter and sunlight and atmospheric gases
change the particulate matter’s chemical and physi-
cal properties, rendering it even more potentially
harmful. So, even though particulate matter dis-
sipates over time and distance, “the health effects
per gram are greater,” says Daniel Jaffe, an atmo-
spheric chemist at the University of Washington
Bothell.
That means that the studies of health effectsAt the California National Primate Research Center,
rhesus macaques that were exposed to wildfire smoke
early in life have immune disorders, nervous system
changes and weakened lungs.“Early life smoke
exposure [in
macaques] ...
changed thetrajectory of lung
development,”
and it doesn’t
appear to be
reversible.
HONG JI