Wildfires are becoming more frequent and severe 

This year, Americans were exposed to wildfires from California and Hawaii and experienced the downstream repercussions of Canada’s record wildfire season, which burned 40,000 square miles of forest—roughly the size of Kentucky.

Wildfires are becoming more frequent and severe, and that isn’t just an environmental problem: Americans were exposed to 66 percent more harmful wildfire smoke this year than in previous record years. 

Wildfire smoke contains tiny pollutants — called fine particulate matter — that can cause damage to the lungs, but it doesn’t stop there. The fine particulate matter is absorbed by the bloodstream and makes its way to the rest of the body and brain. As a result, wildfire smoke exposure is linked to forgetfulness, trouble focusing, brain fog, and even dementia. 

How wildfire smoke exposure immediately affects the brain 

The fine particulate matter affects the brain’s immune cells, the microglia, “causing harm to neurons instead of protecting them,” according to Drexel University emeritus professor of medicine Arnold R. Eiser. “Studies show that these extremely tiny particles may damage neurons or brain cells by promoting inflammation.”

Research shows this process has immediate cognitive effects. That means that students who breathe in more wildfire smoke tend to do worse on tests in school and college, while participants in laboratory experiments score worse on psychological tests measuring memory, thinking, and attention.

Can wildfire smoke exposure increase the risk of dementia?

Continual exposure to these pollutants may have long-term consequences. People living in areas exposed to more fine particulate matter are more likely to have a stroke, which in itself is a risk factor for vascular dementia—a form of the disease caused in part by damage to the brain’s blood vessels. 

Other researchers have also drawn more links between wildfire smoke exposure to Alzheimer’s and other forms of dementia, albeit the risks on an individual level appear to be relatively small. 

If the chances of an older individual developing dementia in any given year are about one or two percent, a five percent increase in risk may be negligible. But in a larger population, this could mean substantially more cases of dementia and a higher burden on healthcare.

Protecting yourself from wildfire smoke

“Education, greater awareness of environmental health concerns and public action are the best ways to minimize risks from environmental neurotoxins [like wildfire smoke],” wrote Eiser.

To help educate people, the Centers for Disease Control and Prevention has developed a tool that allows people to check the air quality index in their area called AirNow

The CDC recommends against physically intensive outdoor activities like jogging on days when the air quality is poor. In addition, individuals should drink lots of water and wear a high-quality mask or respirator like an N95 to filter out these pollutants when outside.