What you should know about fire smoke at home

When fires spread through neighborhoods, they burn all kinds of materials found in cars and houses and everything around them – electronics, paint, plastic, furniture.

Research shows that the mix of the chemicals released when man-made materials like these burn is different from what is emitted during a wildfire and is potentially more toxic. Smoke and ash can blow under doors and around windows in nearby homes, carrying chemicals that are absorbed into furniture, walls and other interior surfaces and continue to fumigation for weeks to months.

As people return to smoke-damaged homes after a fire, there are several steps that can be taken to protect their health before starting to clean.

High levels of metals and VOCs

In 2021, after the Marshall Fire swept through neighborhoods near Boulder, Colorado, my colleagues and I at the Colorado University and Labs heard from many residents who were concerned about the ash and persistent odors in their homes which would otherwise have survived the flames.

In houses that my colleagues were able to test quickly, they found high levels of metals and PAHs – polycyclic aromatic hydrocarbons – in the ash. We also found elevated VOCs – volatile organic compounds – in air samples. Some VOCs, such as dioxin, benzene, formaldehyde and PAHcan be toxic to humans. Benzene is a known carcinogen.

At the time, we could find no information on the physical health implications for people who returned to smoke-damaged homes after a fire. So, to look for models, we surveyed residents affected by the fire six months, one year and two years after the fire.

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

More than half (55%) said they had at least one symptom six months after the fire 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%).

All these symptoms, in addition to having a strange taste in the mouth, have been associated with people who report that their house has a different smell when they come back a week after the fire.

Many respondents to the survey say that the odors diminish over time. Most attribute the improvement in smell to the passage of time, cleaning surfaces and air ducts, replacing furnace filters, and removing carpets, textiles and furniture from the home. Despite this, many still had symptoms.

We also found that living near a large number of burned structures was associated with these health symptoms. We found that for every 10 additional buildings destroyed within 820 feet (250 meters) of a person’s home, there was an associated 21% increase in headaches and a 26% increase in having a strange taste in the mouth.

These symptoms are aligned with what could be expected from exposure to chemicals that we found in the ash and measured in the air in the few. houses damaged by smoke that we were able to study in depth.

Persistent symptoms and questions

There are still many unanswered questions about the health risks from smoke and ash damaged homes.

For example, we don’t yet know what the long-term health implications might be for people living with lingering gases from fire smoke and ash in a home. We found a significant decrease in the number of people reporting symptoms one year after the outbreak. However, 33% percent of people whose homes were affected and responded to a later survey also reported at least one symptom that they attributed to the fire. About the same percentage also reported at least one symptom two years after the outbreak.

We also cannot measure the level of VOCs or metals that each person has been exposed to. But we think reports of a change in the smell of a person’s home a week after the fire show the likely presence of VOCs in the home. It is likely to have health implications for people whose homes are exposed to smoke or ash from a wildfire.

Tips to protect yourself after fires

The fires are more and more burning houses and other structures as well as more people move in the nature-urban interface, temperatures rise fire seasons are getting longer.

If your home survived a wildfire nearby, here are some steps to think before starting cleaning:

• When you’re ready to clean your home, start by protecting it. Wear at least one N95 (or KN95) mask. and gloves, goggles and clothing that covers your skin. Cleaning can send some of those gases and ash into the air again.
• Keep people with heart or lung disease, older adults, pregnant women, children and pets away from cleaning activities.
• Vacuum floors, drapes and furniture. A recent scientific study documents how clean all surfaces in a home can reduce VOC reservoirs and reduce indoor air concentrations of VOCs. Once the air outside is clear, open the windows to let in clean air.
• Avoid harsh chemical cleaners because they can react with the chemicals in the ash.
• Clean your HVAC filter and ducts to avoid spreading the ash further, and change the filters monthly until the smell is gone. Portable air purifiers with carbon filters can help remove VOCs and particles.
• If your car smells like smoke, consider changing the cabin air filter.

This is an update to an article first published on December 23, 2024.

Colleen E. Reidassociate professor of geography, University of Colorado Boulder

This article is republished from The Conversation under a Creative Commons license. Read the original article.