Wildfire smoke linked to increased risk of dementia compared to other pollutants

Wildfire smoke might be worse for your brain than other types of air pollution, according to a new study on the effects of ultrafine smoke particles.

New research published Monday at the Alzheimer’s Association International Conference in Philadelphia focused on the neurological effects of fine particles called PM2.5. They are so named for being 2.5 micrometers wide or less — a diameter 20 or more times smaller than the width of a human hair.

These particles are small enough to infiltrate the bloodstream through the lungs. They have been studied as causes of respiratory and cardiovascular disease and have also been found to cause neurological diseases such as Alzheimer's. The new research finds they may also be linked to an increased risk for dementia.

The study tracked wildfire smoke exposure for 1.2 million adults in California over a decade.

It found that as concentrations of wildfire smoke increased, so did the odds of a person receiving a dementia diagnosis. For every 1 microgram of change in smoke concentrations, the risk of dementia increased roughly 21%.

Wildfire smoke particles are also much riskier than particles from other pollution sources, like industry or transportation: When those concentrations increased by 3 micrograms, the risk of dementia increased 3%.

Researchers aren't sure yet what makes smoke particles that much more dangerous, but they say the work highlights the growing risk of exposure.

RELATED STORY | California's largest wildfire this year has burned nearly 370K acres

Wildfires worldwide are consuming more tree cover than they did just 20 years ago due to the desiccating effects of climate change. In the U.S. , the extent of areas burned by wildfire and the level of severe damage from fires are both increasing.

The smoke from vigorous fire seasons can affect millions of people, as the Canadian wildfires did in 2023 .

This year, fires in the U.S. West have burned large and fast , and officials warn dry conditions will continue to contribute to their spread.

Experts recommend staying indoors when air quality is poor or wearing N95 masks if you have to be out in poor conditions.