The research was led by David Scieszka, a postdoctoral student who assessed the effects of rodents exposed to wood smoke every other day for a period of two weeks.

“We were trying to figure out if the stuff we saw in the wild could at least be partially figured out in the lab,” he said in a press release.

Scieszka and fellow researchers analyzed inflammatory responses in rodent brains as tiny particles from the smoke entered the “blood-brain barrier,” a lining of cells that conceal blood vessels in the brain.

“We were able to measure the inflammatory response amplitude and time frames,” Scieszka said. “We expected it to be a lot shorter. Some of it progressed out to 28 days and we didn’t see a complete resolution, and that was very scary to us.”

Scieszka explained that the blood-brain barrier cells had adapted to the smoke exposure by the second week, but that the immune cells in the brain remained “abnormally activated.”

The study’s senior author, Matthew Campen, said these recent findings are alarming given how regularly people are being exposed to wildfire smoke in recent months.

“Neuroinflammation is the seed for all sorts of bad things in the brain, including dementia, Alzheimer’s disease – the buildup of the plaques – but also alterations in neurodevelopment in early life and mood disorders throughout life,” he said in the release.

“If you’re a firefighter, or if you’re just a citizen in a community that has had some of these dramatic smoke exposures, you could be having neurocognitive or mood disorders weeks or months or weeks after the event.”

Campen added that heavy concentrations of wildfire smoke should prompt people to remain indoors.

“Houses have varying penetrance of particulates. If you’ve got an evaporative cooler, you’re just being exposed to the outdoor air, but a lot of houses will be much more protective.”

N-95 masks offer protection to those who must leave their house despite poor air quality, he added.

Despite the fact that the human body is largely capable of adapting to chronic particulate exposure, Campen said periodic exposures could be reason for concern, even more so than baseline levels of pollutants with less fluctuation.

“Part of what makes this so unique and worrisome is the intermittent nature of it,” he said.

“We have rural communities that are otherwise enjoying clean beautiful air, especially in the Rocky Mountain region, and then all of a sudden they have suffocating levels of pollutants and it’s gone a week later. It’s a real hit to a naïve system.”