Parts of California, Oregon and Montana face unhealthy levels of air pollution as several large fires rage, including the North California Park Firewhich quickly became the fifth largest in the state’s history.
Smoke poses a danger to people in the immediate vicinity and even to some people far away, as smoke from wildfires can travel hundreds or thousands of miles.
The tiny particles contained in this smoke aren’t just bad for your lungs — a series of studies in recent years have found that it also negatively affects brain health, increasing the risk of dementia, cognitive challenges and mental health problems.
“Much of the research on wildfire smoke has historically focused on our lungs and hearts,” said Stephanie Cleland, an assistant professor at Simon Fraser University who studies the health impacts of wildfire smoke. “The shift to focusing on cognitive outcomes and brain health is more recent.”
The latest addition to this body of evidence: Research presented Monday at the Alzheimer’s Association International Conference suggests that wildfire smoke may increase the chances of a dementia diagnosis.
The study analyzed the health records of more than 1.2 million older adults — ages 60 and older — in Southern California from 2009 to 2019.
Researchers looked at where people lived to determine their exposure to fine particles from wildfire smoke and other forms of pollution. Their results showed that the odds of getting dementia increased by 21% for each additional microgram per cubic meter of fine smoke particles that participants were exposed to, on average, over three years.
In contrast, the same increase in exposure to fine particles from other sources — such as cars or factories — was linked to a 3% increase in the odds of getting dementia.
The evidence is preliminary, but it argues that chronic exposure to wildfire smoke contributes to cognitive decline, said Dr. Holly Elser, study author and neurology resident at the Hospital of the University of Pennsylvania.
However, she said, “the threshold at which wildfire smoke begins to pose a risk of dementia is unknown.”
A study published in August similarly, they found that greater exposure to fine particles from various sources, including wildfires, was associated with higher rates of dementia.
Wildfires are becoming more frequent and intense due to climate change — which also increases many people’s exposure to smoke. The frequency of extreme wildfires has more than doubled between 2003 and 2023, a recent study found.
Scientists believe the reason wildfire smoke affects the brain is that the small particles within it can cross the barrier between the bloodstream and the brain, causing inflammation in the central nervous system. Particles can also travel directly to the brain through the nose. This, in turn, can affect people’s ability to think, learn or remember.
Dementia is not the only potential consequence. A study in 2022 found that adults who were recently exposed to wildfire smoke performed worse on a brain training game that measured skills such as memory, attention, flexibility, processing speed and problem solving.
“Within hours and days of exposure to wildfire smoke, we are seeing significant reductions in people’s ability to pay attention,” said Cleland, one of the study’s authors.
Other research published in the same year showed that exposure to wildfire smoke during the school year reduced students’ test scores relative to a smoke-free year.
“The more smoke you smoke, the worse you perform on the tests,” said Marshall Burke, an associate professor of global environmental policy at Stanford University who co-authored the study. “The effect on any individual student is probably very small, but if we add up all students and all schools, it amounts to large aggregate global learning losses.”
Burke said he has some doubts about the dementia findings released this week because smoke from wildfires and other forms of pollution are “not a like-for-like comparison.”
Elser acknowledged that many questions remain about the effects of smoking on the brain. It’s unclear, for example, whether smoking causes dementia in healthy people or only among those who were already at risk.
“It’s a really intriguing question whether this is creating new cases of dementia that would never have occurred, or whether it is simply accelerating the onset of clinically apparent dementia,” she said.
Other lingering questions concern the link between wildfire smoke and mental health. A February study found that exposure to smoke from wildfires in the western US was associated with increased emergency department visits for anxiety. (Air pollution in general has been shown to be associated with depression It is psychotic disorders as schizophrenia.)
Elser said it’s possible that wildfire smoke changes the neurochemistry of people’s brains, which can cause depression and anxiety. But it’s also possible that the anxiety and stress of experiencing or living with a wildfire could independently lead to mental health problems.
Other health consequences of wildfire smoke are much better understood. Scientists have known for decades that when fine particles from smoke are inhaled, they can penetrate deep into the lungs or enter the bloodstream, increasing the risk of asthma, stroke, heart attack, lung cancer and low birth weight in newborns. -born.
Cleland said it’s not just people in fire-prone areas of the U.S. who need to worry about these risks, as evidenced by last summer’s Canadian wildfires that blanketed parts of the Midwest and Northeast in smoke.
“Last summer completely changed our conversation about who is exposed to wildfire smoke,” she said. “Oregon, California, Washington, British Columbia really experience a lot of wildfire smoke, but that doesn’t mean places like the Northeast US or Ontario are immune.”
To reduce exposure to wildfire smoke, experts recommend that people in areas with Air Quality Index Reading of 100 or more, avoid outdoor activities, close all windows, install indoor air filters, and wear an N95 mask if you must leave the house.
This article was originally published in NBCNews. with
