Wildfires are among the most dramatic and destructive events of our time—burning homes, displacing communities, and reshaping entire landscapes. But beyond the visible devastation, a quieter and more insidious crisis is unfolding. As the climate warms and wildfires become more frequent, researchers are uncovering new ways these events are threatening human health.
We’ve long understood that wildfires destroy property and worsen air quality. But now, studies show they’re also reversing decades of progress under clean air laws, creating widespread exposure to toxic pollution in regions once considered safe. And that’s only part of the story.
Emerging science reveals that wildfires don’t just hurt our lungs in the short term—they may accelerate deaths in people already battling lung cancer, and contribute to the spread of respiratory infections like COVID-19, RSV, and influenza. As smoke forces people indoors, often into poorly ventilated spaces, it fuels the very conditions that allow airborne viruses to thrive.
The full public health impact of wildfire smoke is still unfolding—but one thing is clear: the dangers reach far beyond what we can see. And understanding these invisible consequences is critical for protecting those most at risk.
Wildfire Smoke Linked to Higher Lung Cancer Mortality
At the recent 2025 Annual Meeting of the American Society of Clinical Oncology, researchers from the UC Davis Comprehensive Cancer Center shared alarming findings: exposure to wildfire-related air pollution significantly reduces survival rates in lung cancer patients.
The study analyzed data from over 18,000 Californians diagnosed with non-small cell lung cancer (NSCLC) between 2017 and 2020. Researchers discovered that individuals exposed to higher levels of wildfire-derived fine particulate matter (PM2.5) during the year following their diagnosis had a 20% higher risk of death from the disease.
The effects were especially severe in people with Stage 4 cancer who had never smoked—a group whose mortality risk climbed by 55% with greater exposure to wildfire pollution.1
The tiny particles in wildfire smoke can penetrate deep into the lungs and bloodstream, potentially making cancer more aggressive or interfering with treatments. One surprising finding: some patients treated with immunotherapy showed better survival rates during peak PM2.5 days. Researchers speculate that the body’s immune response to pollution might be interacting with the therapy—an insight that demands further exploration.
As wildfires continue to intensify across California and the western U.S., this research underscores the life-or-death importance of clean air for people already fighting serious illnesses.
Wildfires Also Drive Respiratory Infections Indoors
While the cancer study focused on the direct toxic effects of wildfire smoke, another newly published study in PLOS Climate explored how wildfires reshape human behavior—and, in turn, create ideal conditions for infectious diseases to spread.2
Researchers used mobile phone data and epidemic modeling to analyze how people’s habits changed during the devastating 2020 wildfire season on the U.S. West Coast. They found that as air quality plummeted, people spent significantly more time indoors. In Oregon and Washington, indoor activity rose by 10–14%, with cities like Seattle seeing a 16% increase.
Why does this matter?
When large groups of people shelter indoors—often in poorly ventilated spaces—respiratory viruses such as influenza, RSV, and COVID-19 gain a dangerous advantage. The researchers incorporated this behavior into an SIR (Susceptible-Infectious-Recovered) model and found that wildfire-induced indoor crowding measurably increased infection rates, particularly for fast-spreading viruses like the flu.
Even in areas with some level of pre-existing immunity, the model showed elevated infection peaks and greater variability in disease spread compared to unaffected counties. This trend was most pronounced in places like Washington County, Oregon, where wildfire smoke and indoor crowding overlapped.
The study authors emphasized that modest increases in indoor mask use (as little as 10%) could help blunt disease transmission during wildfire events. They urge public health officials to account not just for environmental hazards like smoke—but for the behavioral ripple effects that can worsen health outcomes across a community.
Compounded Risks
Together, this new research paints a stark picture of the public health consequences of wildfires in a warming world:
- Wildfire smoke can accelerate death in lung cancer patients, particularly those in advanced stages of the disease.
- Wildfires drive people indoors, unintentionally creating viral breeding grounds for airborne respiratory infections.
- Even short-term exposure to wildfire pollution can have long-lasting effects, especially for medically vulnerable populations.
This dual threat—of toxic particles and trapped viruses—makes clean indoor air not just a comfort but a necessity.
That’s why creating a “clean room” at home matters so much.
It’s one of the most effective ways to protect your lungs, reduce your exposure to hazardous smoke, and lower the risk of catching or spreading infections indoors. Whether you’re living with cancer, managing asthma, or just trying to keep your family safe, having access to one well-sealed, filtered room during a smoke emergency can be life-saving.
How to Make a “Clean Room” at Home During Wildfire Smoke Events
When the air outside is dangerous to breathe, one of the best ways to protect yourself indoors is by creating a “clean room”—a designated space in your home where the air stays as free from smoke and pollution as possible. Making sure the air is clean can protect you from both smoke and respiratory infections.3
Here’s how to do it:
✅ 1. Choose the Right Room
Pick a room you and your family can comfortably spend several hours in. Ideally, it should:
- Have few or no windows to the outside
- Be easy to seal off from other parts of the home
- Contain no exhaust fans or range hoods that draw air from outside. (A bedroom with an attached bathroom is often a good choice.)
✅ 2. Seal the Space
- Close all windows and doors.
- Turn off any ventilation systems that pull in outdoor air (including HVAC “fresh air” settings or window units with outdoor intake).
- Set your HVAC system or air conditioner to “recirculate” mode if possible.
✅ 3. Use an Air Purifier with HEPA and Activated Carbon
- Choose a portable air cleaner rated for the size of the room.
- Look for units with both HEPA and activated carbon filters, like the Austin Air HealthMate Plus, to remove fine particles and harmful gases found in smoke.
- Run the air purifier continuously on the highest setting while the room is in use.
✅ 4. Stay Cool Safely
- Use ceiling fans, portable fans, or air conditioning to stay comfortable—but avoid devices that draw in outdoor air unless properly filtered.
- If you use an evaporative cooler, seal outside vents or install MERV 13 filters over intake areas.
✅ 5. Avoid Smoke-Producing Activities
- Don’t burn candles, light incense, smoke indoors, or cook anything that produces strong fumes or grease particles.
- Keep the room as particle-free as possible.
Who Needs a Clean Room?
Everyone can benefit from spending time in a clean room during smoke events—but it’s especially important for children, older adults, and people with asthma, COPD, heart disease, or other health vulnerabilities.
Stay Prepared to Evacuate
While clean rooms offer important short-term protection, they’re not a replacement for evacuation if conditions worsen. Keep a go-bag ready, know your local alerts, and follow public health guidance during wildfire emergencies.
We’re Only Beginning to Understand the True Danger
The science is clear—and still unfolding. Wildfires aren’t just natural disasters that destroy forests and homes. They’re accelerating deaths in people with serious illnesses. They’re driving respiratory infections deeper into our communities. They’re compounding health risks in ways we’re only beginning to understand.
And as the smoke thickens, it’s becoming harder to separate the visible flames from the invisible fallout.
Creating a clean room in your home isn’t just a comfort measure—it can be a matter of life or death, especially for those with preexisting conditions, weakened immune systems, or limited access to medical care. Just one room with sealed windows, filtered air, and reduced indoor pollutants can offer critical protection during a smoke emergency.
Wildfire seasons are growing longer, more intense, and more unpredictable. But with awareness, preparation, and the right tools, we can take back some control. Clean air should never be a luxury—and in times like these, protecting it inside our homes might be one of the most important things we do.
REFERENCES
1 Winn, S. (2025 May 28). Wildfire pollution may lower survival of lung cancer patients. UC Davis Health. https://health.ucdavis.edu/news/headlines/wildfire-pollution-may-lower-survival-of-lung-cancer-patients/2025/05
2 Arregui-García B, Ascione C, Pera A, et al. (2025 June 18). Disruption of outdoor activities caused by wildfire smoke shapes circulation of respiratory pathogens. PLOS Climate, 4(6), e0000542. doi: 10.1371/journal.pclm.0000542.
3 Create a clean room to protect indoor air quality during a wildfire. (2025 January 30). US EPA. https://www.epa.gov/emergencies-iaq/create-clean-room-protect-indoor-air-quality-during-wildfire.
