Wildfires were once a rare occurrence, but as the climate becomes warmer and drier, they have become more common and widespread.
Now, a study has shown they could put tens of millions of people at risk of dementia.
It found that people exposed to wildfire pollution have an 18 percent higher risk of developing any type of dementia after just three years of exposure.
While people exposed to pollution not caused by wildfires – such as that from manufacturing or automobiles – have only a one percent increased risk of dementia.
Long-term exposure to pollutants known as total fine particulate matter (PM2.5) is a recognized risk factor for dementia, but less is known about how the small particles of pollution produced by wildfires (ash, carbon monoxide and carbon dioxide, formaldehyde, volatile substances) compounds and other various carcinogens) affect people’s brains.
Researchers studied the medical records of 1.2 million people who had been exposed to wildfire pollution over an average of three years between 2008 and 2019 in California.
According to CAL FIRE, there were 90,157 wildfires during that period and the study found that approximately 81,000 people received a dementia diagnosis during the study period.
The researchers said their results show that wildfires are even more damaging than the already deadly pollution released by traditional means such as cars and factories.
Flames consume a home as the Mountain Fire burns in Camarillo, California, in November 2024
Inmate firefighters battle the Mountain Fire at Swanhill Farms in Moorpark, California, in November 2024.
PM2.5 is small enough to enter the lungs through inhalation and researchers believe the particles then enter the bloodstream and circulate throughout the body, penetrating the brain’s protective barriers.
This, they concluded, can accelerate brain deterioration and lead to dementia.
PM2.5 is also produced by burning gas, diesel, wood, manufacturing and refineries, as well as by lighting candles, although substances released by forest fires are more harmful, according to researchers.
The study looked at diagnoses of Alzheimer’s disease, dementia with Lewy bodies, vascular dementia, frontotemporal dementia, Parkinson’s dementia, and dementia not otherwise specified.
An estimated 7 million Americans age 65 and older had dementia in 2020, and the share of adults age 70 and older with dementia was 10 percent in 2019.
If current trends continue, more than 9 million Americans could suffer from dementia by 2030 and 12 million by 2040, according to the Population Reference Bureau.
But researchers at the University of Pennsylvania and Kaiser Permanente in California, who conducted the latest study, said that as wildfires become more common, so may dementia, and called for more research on the issue.
They also said more needs to be done to mitigate air pollution in especially vulnerable populations, such as minorities and people living in more impoverished neighborhoods.
The researchers concluded: ‘As the climate changes, interventions focused on reducing exposure to PM2.5 from wildfires may reduce dementia diagnoses and related inequalities.
“These latest findings underscore the importance of research that considers the effects of air pollution on potentially vulnerable population subgroups and aims to identify potential strategies to mitigate inequalities in the effects of air pollution exposure.”
An estimated 7 million Americans aged 65 and older had dementia in 2020
Data from researchers at the University of Maryland, estimated that the area burned by wildfires increased about 5.4 percent per year between 2001 and 2023.
PM2.5 refers to the concentration of microscopic particles in the air of 2.5 micrometers or smaller. They are measured in micrograms per cubic meter (μg/m³).
These pollutants are small enough to penetrate deep into the lungs when breathed and circulate throughout the body, including the brain.
The particles can produce highly reactive molecules and free radicals.
Excessive production of these molecules can overwhelm the defense systems of brain cells, causing cell damage, DNA mutations, and impaired cellular function.
Overproduction has also been linked to heart disease, cancer, and Alzheimer’s disease.
Researchers also postulate that PM2.5 from wildfires may cause overactivation of certain types of immune cells that help maintain a healthy balance in the brain, fight infections, and help clear harmful waste from the brain.
Its overactivation can cause harmful effects on the brain and spinal cord.
Pollution from wildfires can also produce an overwhelming amount of something called cytotoxic factors, things that damage or kill healthy living cells.
The researchers added that exposure to PM2.5 can indirectly lead to dementia by disrupting normal processes in the body, which can increase the risk of blood clots, excessive bleeding, blood vessel dysfunctions in the brain and strokes, which could be an underlying risk factor. for dementia.
About two-thirds of the study participants were diagnosed with unspecified dementia. The second most diagnosed dementia was Parkinson’s dementia at 13 percent, followed by Alzheimer’s at 12 percent.
Further analyzes of the data found that study participants younger than 75, those from minority groups, and people living in high-poverty areas had “heightened responses” to PM2.5 from wildfires.
According to the studyPublished in JAMA Neurology, the 2018 wildfire season generated approximately $149 billion in healthcare costs, along with economic and capital damages.