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Exposure to air pollution from wildfires, agriculture could increase your risk of dementia

People exposed to fine particulate matter at higher rates could be most likely to develop dementia over the course of their lifetimes, a new study suggests.

INDIANAPOLIS — New research outlines how people living in places with high levels of air pollution — especially those stemming from wildfires or agriculture — may be more likely to develop dementia over the course of their lifetime. 

The study, published Monday in the journal JAMA Internal Medicine, analyzed data from 27,857 survey participants over an 18-year period, between 1998 to 2016. Nearly 15%, or 4,105 people, developed dementia. Those who developed dementia lived in areas with higher levels of particulate matter air pollution, especially from agriculture and wildfires. 

“Our data suggest that in addition to some of the more obvious health impacts of wildfire smoke like irritation to our throats and eyes along with breathing difficulties, high smoke days might also be taking a toll on our brains,” said Sara Adar, who co-authored the study and is an environmental epidemiology researcher at University of Michigan’s School of Public Health, in a statement. 

The research team said they gathered air quality measurement data from the U.S. Environmental Protection Agency, previous studies and more than 300 geographic variables. Researchers then applied that information to a prediction model that estimated a specific type of air pollutant called PM2.5 at participants’ addresses. 

Then, beginning in 1992, participants were interviewed once every two years about many factors related to healthy aging, including their cognition, overall health and health behaviors. Scientists found that higher levels of the PM2.5 particulate matter air pollution, especially from agriculture and wildfires, were associated with greater risks of dementia. 

Researchers estimated that 188,000 new dementia cases could be attributable to particulate matter exposure in the U.S. It's estimated that about 5.8 million people in the country have Alzheimer’s disease and other dementias, the U.S. Centers for Disease Control and Prevention said

Specifically, researchers found PM2.5 exposure from all studied emissions sources, except dust, were associated with increased rates of dementia. The strongest associations was exposure from agriculture, traffic, coal combustion, and wildfires, according to researchers. 

The study’s authors noted their findings could not be explained by other factors such as individual, neighborhood, socioeconomic status, occupation, or hometown or region of the country.

PM2.5 has long concerned public health officials because the particles are tiny and allow them to deposit into the deepest parts of a human lung and into our bloodstream. Larger PM10 particles can also still settle into our lungs and bodies, but because PM10 can also include PM2.5, that particulate size is referenced more often. 

Exposure to PM2.5 particles is something the World Health Organization has named as a major contributor to declines in human health. Exposure to PM2.5 has been linked to premature death in people with heart or lung disease, nonfatal heart attacks, and irregular heartbeats, according to the Environmental Protection Agency. One recent study from Harvard found more exposure to PM2.5 is linked to higher rates of death from COVID-19

Earlier this year, another analysis released from Harvard University found exposure to find particulate pollutants could increase a person’s risk for developing dementia.

The findings come as poor air quality triggered alerts throughout the U.S., including Indiana, throughout the summer. Indiana has seen double the amount of air quality alerts in 2023 already than in all of 2022. 

The authors hoped their findings would motivate policymakers to tighten limits on air pollution. 

Record number of air quality alerts in the U.S. this year are stemming in large parts to smoke from Canadian wildfires, according to researchers. 

Wildfires are thought to contribute up to 25% of fine particulate matter exposure over a year across the U.S., the study said.

Dementia is the seventh leading cause of death, and one of the major causes of disability and dependency, according to the World Health Organization.

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