Study links wildfire smoke inhalation to increased dementia

A landmark study presented at the Alzheimer's Association International Conference on Monday explored the impact of wildfire smoke on brain health, examining the health records of over 1.2 million Californians over the age of 60.

The study found a strong correlation between wildfire smoke exposure and increased dementia risk. Specifically, for every one microgram per cubic meter increase in fine particulate matter (PM 2.5) from wildfire smoke, the odds of a dementia diagnosis increased by sobering 21 percent versus only 3 percent from other pollutants.

The study is especially sobering to firefighters whose exposure is far higher than that of other people. According to the California Department of Forestry and Fire Protection (Cal Fire), as of Wednesday, 4,665 wildfires occurred in the state this year and 763,425 acres (3,089.5 square kilometers) of land were burned down.

The risk of serious burns, smoke inhalation and death while firefighting already make it an extremely hazardous profession. Prior studies linked firefighting to diseases such as cancer and heart disease, and now an increased risk for neurodegenerative conditions like dementia and Alzheimer's disease ramps up the danger for firefighters.

Xinhua caught up with Firefighter-Paramedic Nicole Richens and Firefighter Eric Richens, a young newlywed couple that work for the Los Angeles Country Fire Department, to ask if the recent report would make them reconsider their risky jobs.

"No, that won't deter us," paramedic Nicole told Xinhua. "We both know it's a dangerous job. We've accepted that. But there are so many other things that contribute to those kinds of health issues. It's hard to tell which one had a bigger impact."

Firefighters are regularly exposed to various toxicants known to affect brain health. Aluminum, lead, mercury, flame retardants, solvents, plasticizers, and air pollutants such as carbon monoxide are among the toxic substances they run into.

These toxicants play a role in the development of neuro-degenerative diseases. While the human body can expel some of these substances, many tend to accumulate, potentially causing long-term health issues.

Neuro-degenerative diseases like dementia and Alzheimer's involve the progressive degeneration of nerve cells in the brain. Research showed that the accumulation of toxicants in the brain can lead to inflammation, oxidative stress, and the buildup of amyloid plaques, all of which are associated with cognitive decline.

PM 2.5 particles, which are 30 times smaller than the width of a single human hair, can penetrate deep into the lungs and enter the bloodstream, causing inflammation. This inflammation is linked to a range of health issues, including heart disease, asthma, and now, dementia.

The study distinguished between PM2.5 from wildfire smoke and other sources, noting a much stronger link between wildfire PM 2.5 and dementia compared to non-wildfire sources.

The findings have significant health implications, particularly for western states increasingly prone to wildfires due to the negative effects of climate change and prolonged drought.

Climate change has drastically exacerbated the frequency and intensity of wildfires, leading to increased exposure to harmful smoke. The number of extreme wildfire events has more than doubled in recent decades, contributing to the growing public health problem of air pollution. Air pollution from wildfires now accounts for up to half of all fine-particle pollution in these regions.

Firefighters' exposure to harmful substances isn't limited to wildfires alone. Structure fires, vehicle fires, and hazardous material incidents all present opportunities for contact with dangerous chemicals.

During firefighting activities, toxicants such as asbestos, benzene, formaldehyde, and polycyclic aromatic hydrocarbons (PAHs) are often also present. Prolonged and repeated exposure to these chemicals can contribute to a cumulative toxic burden on the body, further increasing the risk of developing dementia and other chronic health conditions.

For firefighters, the chronic exposure to these harmful substances over their careers could potentially accelerate these neurodegenerative processes.

In addition to the physical hazards, firefighters face significant psychological stress. The demands of the job, including exposure to traumatic events, long hours, and shift work, contribute to mental health challenges.

Chronic stress and trauma have been linked to an increased risk of cognitive decline and dementia. The combination of physical and psychological stressors makes firefighters particularly vulnerable to neurodegenerative diseases.

As the understanding of the link between toxicant exposure and neurodegenerative diseases evolves, the firefighting profession must adapt to ensure the health and safety of its members.

Wildfire smoke poses a severe hazard not only to those firefighters in immediate proximity but also to people hundreds or even thousands of miles away, because smoke can travel long distances on wind currents.

The study also highlighted that people from racially and ethnic minority groups and those in high-poverty areas are more affected by wildfire smoke's impact on brain health.

While the research underscores the need for further investigation, it also highlights practical steps individuals can take to protect themselves. Staying indoors on days with poor air quality, using home air filtration systems, and wearing fit-tested N95 or KN95 masks can help reduce exposure to PM 2.5.

However, these measures are not always accessible to everyone, particularly those from lower socioeconomic backgrounds.