Months after Marshall Fire, residents returning to Colorado struggle with health and air quality

Six months after the Marshall Fire destroyed more than 1,000 homes in Boulder County, Colorado, more than half of the area’s surviving home residents are suffering from headaches, sore throats and a strange taste in their mouths. reported physical symptoms, which were attributed to poverty. A new study from UW-Boulder sheds light on air quality.

A related study showed that the air quality inside some homes after a fire was comparable to that of downtown Los Angeles on high-pollution days in the 1990s, with harmful gases lingering for weeks.

“Our research suggests there may be serious health effects for people returning to smoke and ash-damaged homes after a fire, and systems need to be put in place to protect them. That suggests something,” said co-author Colleen Reed, associate professor of geography. Author of the study.

The paper, published this week in ACS ES&T Air, is the first to examine air quality inside smoke and ash-damaged homes and assess the impact on the health of people living there. These fires occur at a time when many fires occur at the interface between nature and cities, such as Paradise, California in 2018 and Lahaina, Hawaii in 2023.

“A lot of time has been spent researching wildfire smoke, what you get when you burn plants. But if you burn down your house with all your furniture, electronics, and cars. , what do we get? Until now, little was known about it,” said co-author Jost de Gouw, professor of chemistry and fellow at the Collaborative Research Institute for Environmental Sciences (CIRES). said.

Record-breaking winter heat

Fueled by 160 mph winds and record-dry conditions, the Marshall Fire broke out on December 30, 2021, burning 1,084 buildings in a densely populated area, killing two people, and killing three people. 7,000 people were forced to evacuate.

Once residents returned home, calls began to ring in to scientists at the University of Boulder, just six miles from where the fire started.

“At first they felt really lucky, but when they got into the house, there was ash everywhere and it smelled different, like a campfire or chemicals,” Reid said. “They asked, ‘What should I do? I don’t know if it’s safe to go back.’

Few studies provided answers, so scientists began investigating.

Ten days after the fire, De Gouw’s team installed field instruments at an undamaged house adjacent to the block where the house had been destroyed. They continuously measured the presence of 50 different gases over a period of five weeks.

Meanwhile, Reed and his colleagues created a survey to send to a random sample of residents within the burn boundary and within two miles.

At 6 months, 642 people responded. After one year, 413 people had responded.

Approximately 55% of respondents reported fire-related symptoms six months after the fire, and survey responses were highly dependent on the condition of the home upon return.

For example, people who found ash inside were three times more likely to report a headache than those who didn’t find ash. People who reported smelling strange smells were four times more likely to report a headache than those who didn’t smell strange smells.

Computer mapping analysis showed that people with the same symptoms tended to cluster together. For example, people who lived near destroyed homes, especially in the direction the wind was blowing on the day of the fire, were much more likely to report a strange taste in their mouth.

“These findings are consistent with chemical exposure and suggest that residents of smoke and ash-damaged homes experience lingering air quality and physical health problems even months after the fire. “This suggests that they may be experiencing this,” Reid said.

Long-term effects are uncertain

The authors cannot reveal which chemicals were responsible for the health effects reported by survey respondents. However, measurements in one home found high levels of volatile organic compounds (VOCs), such as benzene, a carcinogen found in gasoline and diesel exhaust.

Dust samples also found high levels of copper, zinc, arsenic, and an industrial pollutant called polycyclic aromatic hydrocarbons (PAHs), which are known to cause eye irritation.

“If your house survives, and your neighbor’s house two houses down burns, those molten materials will drift into the air, settle on furniture, carpets, drywall, etc., and get inside your house,” Reed said. There is a possibility of infiltration.”

The authors stress that VOCs are only thought to be carcinogenic at levels much higher than those found, and that people are regularly exposed to low levels every day through pollution.

Their research found that simple measures like opening windows and using low-cost carbon-activated air filters can significantly improve air quality.

One year after the fire, the number of residents reporting symptoms had fallen to just 33%, and most said their confidence in the air quality in their homes had improved.

Until more research is done, researchers cannot say whether such exposure may cause long-term health problems.

Nevertheless, Reid urged anyone entering homes damaged by smoke or ash in the immediate aftermath of the Wildland Urban Interface (WUI) fire to use caution and wear a KN95 mask and gloves. There is.

They hope the ongoing research will lead to clearer guidelines for policymakers and insurance companies about when people can safely return to smoke-damaged homes.

“This wasn’t just a fire. It felt personal,” De Gouw said. “It made this work even more meaningful knowing that we could at least begin to provide some answers to the community.”