Three Years After the Marshall Fire, Residents Still Face Lingering Health Risks from Smoke-Damaged Homes

Three years ago, on Dec. 30, 2021, a wind-driven wildfire raced through two communities just outside Boulder, Colorado. In the span of about eight hours, more than 1,000 homes and businesses burned. The fire left entire blocks in ash, but among them, pockets of houses survived seemingly untouched. The owners of these homes may have felt relief at first. But fire damage can be deceiving, as many soon discovered.

When wildfires like the Marshall Fire reach the wildland-urban interface, they are burning both vegetation and human-made materials. Vehicles and buildings burn, along with all of the things inside them – electronics, paint, plastics, furniture. Research shows that when human-made materials like these burn, the chemicals released are different from what is emitted when just vegetation burns. The smoke and ash can blow under doors and around windows in nearby homes, bringing in chemicals that stick to walls and other indoor surfaces and continue off-gassing for weeks to months, particularly in warmer temperatures.

Tests in homes found elevated metals and VOCs

In the days after the Marshall Fire, residents quickly reached out to nearby scientists who study wildfire smoke and health risks at the University of Colorado Boulder and area labs. People wanted to know what was in the ash and causing the lingering smells inside their homes.

In homes we were able to test, my colleagues found elevated levels of metals and PAHs – polycyclic aromatic hydrocarbons – in the ash. We also found elevated VOCs – volatile organic compounds – in airborne samples. Some VOCs, such as dioxins, benzene, formaldehyde and PAHs can be toxic to humans. Benzene is a known carcinogen.

Symptoms 6 months after the fire

Even six months after the fire, we found that many people were reporting symptoms that aligned with health risks related to smoke and ash from fires.

More than half (55%) of the people who responded to our survey reported that they were experiencing at least one symptom six months after the blaze that they attributed to the Marshall Fire. The most common symptoms reported were itchy or watery eyes (33%), headache (30%), dry cough (27%), sneezing (26%) and sore throat (23%).

Lingering symptoms and questions

There are a still a lot of unanswered questions about the health risks from smoke- and ash-damaged homes.

For example, we don’t yet know what long-term health implications might look like for people living with lingering gases from wildfire smoke and ash in a home.

Tips to protect yourself after future wildfires

Wildfires are increasingly burning homes and other structures as more people move into the wildland-urban interface, temperatures rise and fire seasons lengthen.

It can be confusing to know what to do if your home is one that survives a wildfire nearby. To help, my colleagues and I put together a website of steps to take if your home is ever infiltrated by smoke or ash from a wildfire.

• When you’re ready to clean your home, start by protecting yourself. Wear at least an N95 (or KN95) mask and gloves, goggles and clothing that covers your skin.

• Vacuum floors, drapes and furniture. But avoid harsh chemical cleaners because they can react with the chemicals in the ash.

• Clean your HVAC filter and ducts to avoid spreading ash further. Portable air cleaners with carbon filters can help remove VOCs.

Conclusion

Residents of the Marshall Fire area, like those affected by other wildfires, face ongoing health risks from smoke- and ash-damaged homes. The findings of this study highlight the importance of understanding the health implications of living in a home with lingering smoke and ash. By taking steps to mitigate these risks, residents can reduce their exposure to harmful chemicals and minimize the impact on their health.

FAQs

Q: What are the most common symptoms reported by residents after a wildfire?

A: Itchy or watery eyes, headache, dry cough, sneezing, and sore throat are the most common symptoms reported by residents after a wildfire.

Q: What are the health risks associated with smoke- and ash-damaged homes?

A: The health risks associated with smoke- and ash-damaged homes include respiratory problems, eye and skin irritation, and potential long-term health implications due to exposure to toxic chemicals.

Q: How can residents protect themselves after a wildfire?

A: Residents can protect themselves by following steps to mitigate the risks associated with smoke- and ash-damaged homes, including wearing appropriate protective gear, cleaning with care, and using air purifiers and vacuum cleaners with HEPA filters.