While California and western Canada are currently being ravaged by extreme wildfires, a major study has looked at the impact of smoke on brain health. The research found that, more than any form of pollution, exposure to wildfire smoke could significantly increase the risk of dementia.
Inhaling the smoke emitted by these fires, made up of airborne particles, carbon monoxide and other chemical substances, can cause respiratory and cardiovascular symptoms, as the French Agency for Food, Environmental and Occupational Health & Safety explained last year.
But smoke from wildfires could also be harmful to brain health, as this new US study suggests.
“Previous research has found that exposure to PM2.5 fine particulate matter is associated with dementia, but in light of our large, long-term study, it’s apparent the risk from exposure due to wildfire smoke is an even bigger concern,” said study first author Holly Elser.
The findings, presented at the Alzheimer’s Association International Conference in Philadelphia, are based on a 10-year study (2009-2019) analysing the medical records of over 1.2 million Southern Californians aged 60 and over.
For their research, the study authors used air quality-monitoring data, satellite images, and other techniques designed to separate fine particles from wildfires from those generated by other sources such as cars or factories.
They then assessed each participant’s exposure to these sources of fine particles, based on their place of residence, and compared the data with any diagnoses of dementia in medical records.
‘Increasing threat to brain health’
The study suggests a significant risk of dementia diagnosis in people exposed to wildfire smoke, more so than when exposed to other forms of air pollution.
In detail, the study shows a 21% increase in the risk of dementia diagnosis for each increase of one microgramme (μg) per cubic metre in the concentration of fine particles generated by wildfires over an average of three years of exposure.
This is a much higher rate than for other sources of fine particles, with a 3% increased risk of dementia diagnosis for each 3μg increase in fine particle concentration per cubic metre.
“With the rising global incidence of wildfires, including in California and the western US, exposure to this type of air pollution is an increasing threat to brain health,” said Claire Sexton of the US Alzheimer’s Association.
“These findings underscore the importance of enacting policies to prevent wildfires and investigating better methods to address them.”
According to the researchers, the fine particles generated by wildfires could be more harmful to brain health owing to their higher concentration of toxic chemicals, their smaller diameter compared to other fine particles, and the higher temperatures at which they are produced.
To reduce their exposure to these particles, the populations concerned are advised to check and change their air filtration systems if necessary, and to stay indoors or wear a suitable mask in the event of poor air quality.
This is not the first study of its kind to establish a link between wildfire smoke and brain health. Last August, researchers at the University of New Mexico’s Health Sciences suggested that inhalation of these fumes may be responsible for inflammation of the brain, with an increased risk of neurocognitive and mood disorders.
Separate research conducted in the US reported a link between exposure to wildfires and anxiety disorders, another health consequence of these increasingly frequent fires.