Wildfires across the western U.S. are pushing smoke into communities miles away, leaving lasting air quality issues. Naturally, many people worry about what breathing this smoke might mean for their health. Wildfire smoke is a complex mix of chemicals and tiny particles that can bypass our body’s defenses and directly impact our lungs—and potentially much more.
As environmental toxicologists, we’re investigating the health impacts of wildfire smoke, looking into unexpected areas such as sperm health and brain function. With more people exposed to wildfire smoke each summer—and this trend expected to continue as wildfires worsen with climate change—it’s crucial to understand the effects of this smoke and how to protect ourselves. Although air pollution in cities comes from sources like industrial emissions and car exhaust, which have been linked to male reproductive health issues, studies on wildfire smoke as a specific pollutant are still limited.
We already know that pollution from industrial sources can affect sperm shape, motility, and even genetic structure. A recent study found that baby rats born to parents exposed to wood smoke showed cognitive and behavioral issues. At Boise State University, in partnership with Northeastern University, we’re exploring how wildfire smoke affects mouse sperm, focusing on tiny cellular changes that may show how harmful effects could be inherited. Mice aren’t humans, but their responses can help us understand potential risks for people.
In our lab, we simulated a wildfire environment by burning Douglas fir needles, which recreates the smoke exposure wildland firefighters experience. The results were striking: we observed changes in sperm DNA methylation among exposed mice. Methylation is key because it controls gene expression, working like a dimmer switch to adjust how genes function. If environmental factors disrupt methylation in the wrong places or times, it could lead to significant health issues. Shockingly, the impact of wood smoke on sperm was very similar to effects seen from cigarette and cannabis smoke.
We need more research to understand how these sperm changes could impact future generations and human health. Studying groups with high smoke exposure, like wildland firefighters, could offer valuable insights, but long-term data on these exposures and health effects remain scarce. Wood smoke exposure has also been linked to brain health risks, including cognitive decline, which may worsen Alzheimer’s disease. A recent article in Epigenetics Insights highlighted how particles from wildfire smoke—or the inflammatory responses they trigger—can reach the brain and cause harm. These tiny particles may enter the bloodstream after being inhaled and make their way to the brain, or they could remain in the lungs and send inflammatory signals to the brain through the blood. Evidence even suggests that some particles might bypass the lungs entirely and travel directly to the brain through nerve bundles in the nose.
Changes in DNA methylation are particularly concerning in brain areas essential for learning and memory, like the hippocampus. Environmental factors that alter methylation patterns could explain why one identical twin might develop Alzheimer’s while the other does not, even with identical genetics. The potential impact of wildfire smoke extends beyond lung health to critical areas like reproductive and brain health, and other studies have also linked it to heart inflammation and preterm birth risks, underscoring the urgency of these findings.
To protect yourself during wildfire season, stay updated on air quality warnings. The Environmental Protection Agency and companies like PurpleAir offer interactive maps to track air quality in real-time, and affordable air monitors can help keep tabs on your home environment. Changing furnace and air conditioner filters regularly and using portable HEPA air purifiers in high-traffic areas can also help. If you wear a mask, make sure it’s an N-95 or higher, as these can filter at least 95% of harmful particles. Cloth masks, unfortunately, aren’t effective against smoke due to their limited filtration and fit.
As climate change continues and the West faces more intense dry seasons, wildfire smoke is likely to become a regular summer hazard. Being aware of the risks and taking proactive steps to protect yourself and your loved ones is more essential than ever.