Smoke studies reveal new degree of harm
Humans exposed even briefly risk array of ill effects
“This complex mixture of smoke, when it includes homes and buildings and vehicles, is a very toxic mixture.”
Bonnie HolmesGen, California Air Resources Board
As California’s fire season begins to cough up nasty, gray air — all too familiar over the past few years — scientists are learning that wildfire smoke may be a lot more harmful than previously thought, even for those living far from the flames.
Several recent studies reveal new and elevated risks associated with smoke exposure, including lead poisoning, increased susceptibility to COVID19 and more severe flareups of respiratory illnesses, like asthma. The findings come alongside research that’s in the works on the longterm effects of even brief bouts with smoke, which could include cancer and heart disease.
Wildfire smoke has been known for decades to pose health issues, but the full scope of the problem is only coming into view as burning forests become more ubiquitous and researchers dig deeper into the fallout.
“What happened in 2020 was unprecedented, and what happened in San Francisco with those famous photos of the orange sky was unprecedented,” said Tom Corringham, a research economist at Scripps Institution of Oceanography at UC San Diego who studies the impacts of climate change, including wildfires. “If these fires continue the way they have and we keep seeing this crazy smoke, it’s something we need to think more about.”
This year’s wildfires, including
the massive Beckwourth Complex north of Lake Tahoe and the Bootleg Fire across the Oregon border, have already begun spewing foul air hundreds of miles. It’s just the beginning of what’s likely to be a difficult fire season because of the drought. Particles from wildfire smoke were reported this week as far away as the Midwest and Northeast.
One of the latest studies on smoky skies, released last week by California’s air regulator, documents dangerous levels of toxic metals in the smoke.
The research by the California Air Resources Board sought to understand the pollution associated with blazes that burn down communities, not just trees. The work focused on the 2018 Camp Fire, which destroyed the Butte County town of Paradise and nearly 19,000 buildings.
State scientists found that the particulate matter in this smoke — airborne particles that lodge into people’s lungs and are the source of most smokerelated problems — contained lead, zinc, calcium, iron and manganese. Some of these metals traveled more than 150 miles, to Modesto and San Jose, according to the report.
The most concerning metal is lead, which turned up at concentrations 50 times above normal in Chico, the location of the monitoring site nearest to the Camp Fire. This level of air pollution lasted only one day, but any increase can be harmful, the report said. Lead exposure has been linked to high blood pressure and reproductive issues in adults and learning disabilities in children.
“That’s the whole point of the study,” said CARB’s Health and Exposure Assessment Branch Chief Bonnie HolmesGen. “This complex mixture of smoke, when it includes homes and buildings and vehicles, is a very toxic mixture, and people don’t want to be breathing it.”
As in previous research on smoke, the health risk for children, seniors, pregnant women, and people with heart or respiratory conditions is reported to be greatest.
Another study released this month, published in the Journal of Exposure Science and Environmental Epidemiology, shows a correlation between California’s wildfire smoke and the number of cases of COVID19.
According to the research, positive coronavirus tests increased 17.7% during a twomonth period of smoky air last year in the Reno area, which experienced fallout from California’s fires as much as most places in California.
Particulate matter in smoke, when it gets into people’s lungs, is believed to compromise immune response and make it easier for respiratory viruses to settle in. The particles can also help spread viruses.
“This is important to be aware of as we are already confronting heavy wildfire smoke from the Beckwourth Complex fire and with COVID19 cases again rising in Nevada and other parts of the Western U.S.,” said Daniel Kiser, one of the study’s lead authors and an assistant research scientist at the Desert Research Institute in Reno.
A third study on smoke, which Corringham coauthored earlier this year, shows that particulate matter in wildfire smoke is different than particulate matter in smoke from other sources, such as car tailpipes, and it’s often a lot more harmful.
Corringham and his colleagues analyzed data from 14 years’ worth of hospital visits in Southern California. They found that wildfirecaused upticks in PM 2.5, particulate matter that is 2.5 micrometers in size or less, increased hospital admissions for respiratory problems as much as 10%, while upticks caused by other sources increased admissions by 1%.
The researchers didn’t study why the particulate matter in smoke appeared more damaging. But they believe it’s because of the smoke’s more toxic composition and its shortterm prevalence, making it harder for people to get away from. Their work was published in the journal Nature Communications.
Like others studying wildfire smoke, Corringham urges people to pay attention to air quality forecasts, perhaps downloading an app on their phone, and prepare in advance for smoky skies.
State air regulators recommend setting up highefficiency air filters at home and reducing strenuous outdoor activities, staying indoors as much as possible and wearing N95 masks when smoke is present.
On Tuesday, the Bay Area forecast was free of smoke due mainly to westerly winds. Parts of the North Coast, northern Sierra and Tahoe basin, however, remained under smoke advisories.
A lot more is likely to become known about the dangers of wildfire smoke in coming years, namely on the longterm impacts of shortterm exposure, which is becoming increasingly common for Californians.
CARB is already funding research on the health problems of primates exposed to wildfire during infancy. The agency is also planning studies that address the effects of repeated shortterm bouts with wildfire smoke.
“With the smoke that blanketed California last year, there’s been a lot of questions and concerns,” said HolmesGen, with CARB. “We’re trying to provide additional information.”