From Greece to Hawaii and Canada, many nations and regions have been ravaged by wildfires this year. In addition to effects on the respiratory and cardiovascular systems, inhalation of fumes may also be harmful for brain health, potentially even leading to neurocognitive or mood disorders, a new study reveals.
Increasingly frequent and intense droughts and heatwaves encourage the outbreak of forest fires, which can then spread rapidly thanks to the wind or the nature of the vegetation and soil. In recent times, such instances have been observed in parts of Europe, North America, the Pacific, and North Africa.
This has serious consequences on both environment and human health, as France’s Agency for Food, Environmental and Occupational Health & Safety outlined recently.
It explains that inhalation of these fumes – which can generate suspended particles, carbon monoxide and other chemical substances – can lead to respiratory and cardiovascular issues, and is particularly damaging to firefighters and people with chronic respiratory conditions and cardiovascular disease.
But there could be an even greater impact on health, according to a new study by researchers at the University of New Mexico’s Health Sciences. Their research, published in the Journal of Neuroinflammation, reveals more specifically that inhalation of such smoke could be responsible for inflammation of the brain, and that such inflammation persists for at least a month.
“The inflammatory process affects the hippocampus – the region associated with learning and memory – altering neurotransmitters and signalling molecules,” explains study author Matthew Campen.
For their research, the scientists exposed rodents to smoke from a wood fire every other day for two weeks.
At the end of the experiment, they identified pro- and anti-inflammatory responses when tiny particles of smoke managed to cross the blood-brain barrier, whose function is to prevent, among other things, the passage of foreign substances, sometimes toxic, and other pathogenic agents, into the brain.
What’s more, this inflammation was not short-term, and may even be long-lasting.
“We were able to measure the inflammatory-response amplitude and timeframes. We expected it to be a lot shorter. Some of it progressed to 28 days and we didn’t see a complete resolution, which was very scary to us,” says David Scieszka, who led the research.
This observation is all the more alarming as forest fires are multiplying at speed around the world, exposing a growing number of people to these unhealthy fumes.
According to Campen, “neuroinflammation is the seed for all kinds of bad things in the brain, including dementia, Alzheimer’s disease – the buildup of plaques – plus alterations in neurodevelopment in early life, and mood disorders throughout life”.
He added: “If you’re a firefighter, or 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 thereafter.”
In the event of a forest fire, the French government recommends staying indoors – provided your home is not in danger – and plugging air vents. It is also advisable to apply a damp cloth over one’s mouth and nose to avoid inhaling smoke.
Some experts recommend wearing an N95 mask, designed to filter out particles potentially harmful to health and using an air purifier, preferably fitted with a high-efficiency particulate air (Hepa) filter.