Researchers find that wildfire smoke poses neurological hazards

Inhaled microscopic particles from wood smoke can work their way into the bloodstream and reach the brain, putting people at risk for premature aging and various forms of dementia, depression, and even psychosis

Satellite photo, smoke from California fires
Satellite photo, smoke from California fires at 7:01 p.m. PDT Aug 4, 2021.

The research outlined below by the University of New Mexico Health Sciences Center is further evidence of the importance of smoke management. Land managers, agency administrators, and incident management teams need to constantly consider methods of reducing smoke exposure to firefighters and the downwind population when planning, conducting, or suppressing wildfires and prescribed burns.


Woodsmoke from massive wildfires burning in California shrouded much of the West last summer, making it harder for people suffering from respiratory illnesses to breathe.

Those respiratory consequences can be dangerous — even life-threatening — but Matthew Campen, PhD, a professor in The University of New Mexico College of Pharmacy, sees another hazard hidden in the smoke.

In research published online this week in the journal Toxicological Sciences, Campen and his colleagues report that inhaled microscopic particles from woodsmoke work their way into the bloodstream and reach the brain, and may put people at risk for neurological problems ranging from premature aging and various forms of dementia to depression and even psychosis.

“These are fires that are coming through small towns and they’re burning up cars and houses,” Campen says. Microplastics and metallic particles of iron, aluminum and magnesium are lofted into the sky, sometimes traveling thousands of miles.

In the research study conducted last year at Laguna Pueblo, 41 miles west of Albuquerque and roughly 600 miles from the source of wildland fires, Campen and his team found that mice exposed to smoke-laden air for nearly three weeks under closely monitored conditions showed age-related changes in their brain tissue.

The findings highlight the hidden dangers of woodsmoke that might not be dense enough to trigger respiratory symptoms, Campen says.

As smoke rises higher in the atmosphere heavier particles fall out, he says. “It’s only these really small ultra-fine particles that travel a thousand miles to where we are. They’re more dangerous because the small particles get deeper into your lung and your lung has a harder time removing them as a result.”

When the particles burrow into lung tissue, it triggers the release of inflammatory immune molecules into the bloodstream, which carries them into the brain, where they start to degrade the blood-brain barrier, Campen says. That causes the brain’s own immune protection to kick in.

“It looks like there’s a breakdown of the blood-brain barrier that’s mild, but it still triggers a response from the protective cells in the brain — astrocytes and microglia — to sheathe it off and protect the rest of the brain from the factors in the blood,” he says.

“Normally the microglia are supposed to be doing other things, like helping with learning and memory,” Campen adds. The researchers found neurons showed metabolic changes suggesting that wildfire smoke exposure may add to the burden of aging-related impairments.

The research team included colleagues from the College of Pharmacy and the UNM Departments of Neurosciences, Geography & Environmental Studies, and Earth and Planetary Sciences, as well as researchers at Arizona State University, Michigan State University and Virginia Commonwealth University.


Story provided by University of New Mexico Health Sciences Center. Original written by Michael Haederle.

Journal Reference:

David Scieszka, Russell Hunter, Jessica Begay, Marsha Bitsui, Yan Lin, Joseph Galewsky, Masako Morishita, Zachary Klaver, James Wagner, Jack R Harkema, Guy Herbert, Selita Lucas, Charlotte McVeigh, Alicia Bolt, Barry Bleske, Christopher G Canal, Ekaterina Mostovenko, Andrew K Ottens, Haiwei Gu, Matthew J Campen, Shahani Noor. Neuroinflammatory and neurometabolomic consequences from inhaled wildfire smoke-derived particulate matter in the Western United States. Toxicological Sciences, 2021; DOI: 10.1093/toxsci/kfab147

Thanks and a tip of the hat go out to Gerald.

Forecasts for wildfire smoke

Above: The forecast for the maximum levels of wildfire particulate matter (PM 2.5) for August 14, 2017. Experimental product by U.S. Forest Service/BlueSky.

(Originally published at 10:40 a.m. MDT August 14, 2017)

These maps are experimental products developed by U.S. Forest Service researchers using the BlueSky modeling framework, in this case to predict the distribution of very small particulate matter (PM2.5) produced by vegetation fires. Their efforts link a variety of independent models of fire information, fuel loading, fire consumption, fire emissions, and smoke dispersion.

The map above is for Monday, August 14 and the one below is for Tuesday, August 15.

wildfire smoke pm25
The forecast for the maximum levels of wildfire particulate matter (PM 2.5) for August 15, 2017. Experimental product by U.S. Forest Service/BlueSky.

Here is information from the EPA about particulate matter:

Particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. Particles less than 10 micrometers in diameter [PM10] pose the greatest problems, because they can get deep into your lungs, and some may even get into your bloodstream.

Fine particles (PM2.5) are the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas. They can only be seen with an electron microscope. Fine particles are produced from all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes.