Air Alert
UM research finds lingering health effects after major 2017 smoke event
By Cary Shimek
Lightning sparked the Rice Ridge Fire near the end of July 2017. During the next seven weeks, the blaze charred more than 150,000 acres of Montana forest as it was contested by an army of 700 wildland firefighters.
Where there’s fire, there’s smoke. A blanket of white descended on nearby Seeley Lake, turning that small town into a gray ghost land for the next 49 days. It was oppressive — a smoky campfire residents couldn’t escape without actually fleeing the area.
Researchers know airborne particles less than 2.5 micrometers (PM2.5) in diameter are most likely to threaten human health, and air quality is measured in micrograms per cubic meter. Air alerts start when PM2.5 rises to 36 micrograms per cubic meter. At this point, the elderly and people with underlying conditions are told to limit activity. At 150 micrograms per cubic meter, high school football teams can’t practice outdoors or host games.
During the entire Seeley Lake smoke event, the air averaged 220 micrograms per cubic meter. Some daily averages spiked to over 600, and hourly averages could hit 900.
Andi Bourne, editor of the Seeley-Swan Pathfinder newspaper, lived through it all, covering the fire and smothering smoke that threatened her small community.
“It was just depressing,” she says. “You wake up and you can’t see across the lake or see the mountains because of the haze. It felt like it was pressing down on you, and it would get worse during the day instead of better. We stayed indoors a lot, so it felt more like the middle of winter than summer. It was so isolating — kind of like what we all are experiencing with COVID right now.”
She asked Seeley old-timers if they had ever experienced anything like it.
“They said it was just unprecedented for it to go on so long,” Bourne says. “I think the valley has been socked in like that for a day or two, but it had never hung around for as long as it did. It’s not comparable to anything. So when I first heard about the University of Montana study, I thought, yeah, somebody should be studying the health effects.”
Chris Migliaccio is an immunologist and researcher with UM’s Center for Environmental Health Sciences. For more than a decade, he has delved into the long-term health risks associated with exposure to wildfire smoke and biomass burning. A few weeks after the Rice Ridge Fire blew up, he got a call from the Missoula City-County Health Department.
“They said there were people exposed to extremely high levels of smoke,” he says. “Was there anyone at the University interested who had the capacity to come up?”
Migliaccio and the team moved fast to get approval for non-invasive human testing. He soon led a group of pharmacy, community health and biomedical faculty members — along with pharmacy, nursing and social work students — to set up a testing event in the Seeley Lake community center.
The team of about 25 researchers arrived the day after rain finally knocked down smoke in the area, and they requested community volunteers so they could start gathering baseline data. The team was able to use this initial screening to land a $400,000 grant from the National Institute of Environmental Health Sciences to continue the study long term. Migliaccio says they tapped emergency funds usually devoted to studying the aftereffects of events like hurricanes.
The subjects provided information on height, weight, demographics, behavior, mental health, breathing and lung function. Mary Buford, a staff scientist in Migliaccio’s lab, is certified to conduct spirometry — standard testing for how well lungs function. In one test, subjects try to expel as much air as possible from their lungs in the first second. A healthy 19-year-old should be able to expel 85% of her lung volume in the first second of the spirometry test. For those 60 or older, the accepted range is 70%.
The team gathered data from a cohort of about 100 people in 2017. But what made their study more significant is they returned again in 2018 and 2019 to check most of the same people. They searched for possible health effects from the unprecedented smoke exposure that could be revealed over time.
“What we found was a decrease in their lung function as a cohort,” Migliaccio says. “We calculated that 10% of the people we tested in 2017 were below the limit of normal. Then, when we came back in 2018, 45% had dropped below the limit of normal. So there was some delayed adverse effect. It was not at all what we expected.”
The 2018 and 2019 fire seasons were much less intense than 2017 in western Montana, so people in Seeley Lake have not endured further terrible smoke exposures. Migliaccio says when they returned in 2019, some people had gotten better, with only 33% testing below the normal limits. (With the onset of COVID-19 in 2020, researchers have not been able to return for additional testing.)
Migliaccio’s team also has studied groups of people in the Montana towns of Thompson Falls and Hamilton, which had wildfire smoke in 2017 but far less than Seeley Lake. They have detected some reduction in lung function in those communities, but it’s not as pronounced as what they found in Seeley.
The researchers also quizzed their subjects about whether they had the seasonal flu vaccine and whether they caught the flu in either of the following two flu seasons. Migliaccio says once again they detected a lingering aftereffect: The normal flu infection rate (6% to 20%) jumped into the upper 20 percentage rate in the winter of 2017–18. But the following winter, the rate fell back to normal. Researchers in UM’s School of Public and Community Health Sciences also examined hospital records after 2017 in the study areas and found increased reports of influenza.
“It looks like there is strong evidence of increased susceptibility to respiratory infections after a significant smoke exposure like they had in Seeley,” Migliaccio says. “I was part of a study where we exposed mice to wood smoke prior to inoculation with S. pneumoniae. We found a higher level of bacterial deposition which, like the studies from the 2017 fires supports this idea of increased risk of lung infections following smoke exposures.”
Another concern, he says, is that a bad fire season in Montana could boost infection rates during the 2020 coronavirus pandemic. European scientists found increased COVID-19 mortality rates in northern Italy in regions with higher air pollution.
With climate change heating the globe, indicators point to longer, more-frequent fire seasons in Montana. What advice does Migliaccio have for someone stuck in a prolonged smoke exposure?
“HEPA filters,” he says. (HEPA stands for high efficiency particulate air filter.) “You can get stand-alone- filters to generate a safe air space in your home or office. I heard of one older couple during the smoke in Seeley — people dealing with underlying conditions — and they said, hands down, that they are sure the filter saved their lives. A number of people used the filters in the Seeley area in 2017, and then, of course, all the stores ran out of them.”
Migliaccio says there is a lot they still need to learn.
“I want to know, if we don’t have fires, will the people in Seeley return to lung function levels they had before 2017? Or is this lung decrease the new normal? If you get hit by multiple bad fire seasons in a row, does your lung function keep decreasing? These are important questions to understand the long-term health effects of these exposures.”
Bourne, the Seeley Lake editor, endured the horrible smoke of 2017 with her husband, Nathan, and 1-year-old daughter, Olivia. A former wildland firefighter, Bourne was a fit 37-year-old at the time and continued to go for runs when the particulate would thin a bit. They also had a HEPA filter going in Olivia’s room.
She and her husband participated in the UM study to see if the scientists could detect any sort of health impacts. And even though Bourne admits to being asthmatic since she was a toddler, her family as a whole seems unaffected by that 49 days of smoke.
But …
“Both of us, when we get sick, it has gone to our lungs, and we just can’t seem to shake it,” she says. “It hangs on a lot more. When my husband gets sick now, he’s feeling rough for a month. It’s just crazy.”
Not that they let anything slow them down for long. When the Rice Ridge Fire forced the couple to evacuate Seeley Lake for two weeks, they just moved four miles north of town and set up a newspaper office in their in-law’s house.
The newspaper didn’t miss an issue. •
