The ash left behind by the Los Angeles wildfires might be toxic, experts warn

[January 22, 2025]  By MELINA WALLING

Toni Boucher threw up the first time she saw the charred remains of her home and neighborhood after this month’s deadly Los Angeles-area wildfires. Now she wonders if it’s worth it to go back to sift through the ashes and try to find her grandmother’s wedding ring.

It’s not just that she’s worried about the trauma she experienced from seeing the destruction in Altadena, where Boucher, 70, has lived for decades. She is also concerned about possible health risks.

“They talk about asbestos and they’re talking about lead and they’re talking about all of the things that have burned in the loss of the homes and the danger of that,” Boucher said.

Experts warn that the blazes unleashed complex chemical reactions on paint, furniture, building materials, cars, electronics and other belongings, turning ordinary objects into potentially toxic ash that requires protective gear to handle safely. The ash could include harmful lead, asbestos or arsenic, as well as newer synthetic materials.

“Ash is not just ash. Go back to the garage or what’s in your home. What is your furniture made out of? What are your appliances made out of? What is your house made out of?” asked Scott McLean, a former deputy chief of the California Department of Forestry and Fire Protection's communications bureau. “A lot of it’s petroleum product and different composites that are extreme hazards due to fire when they combust."

That is especially a problem when people start to sift through fire damage. Studies show that people involved in recovery in ash-affected areas could face health risks from breathing in whatever is there.

Even safe chemicals commonly found in household materials — such as titanium dioxide in paint or copper in pipes — can form compounds that are more reactive after a fire, said Mohammed Baalousha, a professor of environmental health sciences at University of South Carolina, who studies ash samples to better understand what materials are present and how they change in the wake of wildfires.

Scientists are still trying to understand exactly what those chemical changes do to human health, not just in California but in places such as Maui and other areas scarred by wildfire.

Maui residents were kept out of contaminated areas for nearly two months, but they still worry about long-term health impacts. In California, officials aren't letting residents return to many locations, likely for at least a week, while they restore utilities, conduct safety operations and search for people, according to Los Angeles County's recovery website.

Search and rescue workers dig through the rubble left behind by the Eaton Fire, in Altadena, Calif., Tuesday, Jan. 14, 2025. (AP Photo/Jae C. Hong)

Some chemicals are linked to cardiovascular disease and reduced lung function. Other adverse health effects might arise from inhaling more mobile and toxic forms of arsenic, chromium and benzene. Exposure to magnetite, which can form when fire burns iron, has been linked to Alzheimer's disease, for example.

“It really could take a long time to tease out all of the potential health effects of these particles” because of how many complex chemical reactions are going on and how many substances still remain to be studied, Baalousha said.

Researchers point to the variety of health problems potentially linked to dust from the Sept. 11, 2001, attacks.

“I always kind of reminded myself of all the people that ran into the World Trade Center on 9/11, and were really there for not that long of a period of time in terms of their total exposure,” said Jackson Webster, who studies fire aftermath as a professor of civil engineering at California State University, Chico. “But there is increased cases of all kinds of different illness, sickness.”

Baalousha added that scientists also worry about where all the waste will go. Some potentially hazardous materials could end up in drinking water or even flow into the ocean, adversely affecting marine life. That's something experts in Hawaii are studying after the deadly fire in Maui last year.

While researchers continue their work, people returning to their homes in California should put their safety first, he said.

“We know it’s a lot of emotions and feelings going on that you can put down your guard, but you shouldn’t do that,” Baalousha said. “Just be safe. Be careful. Put all the gear you can — at least an N95 mask, gloves — and stay safe. Because you lost your property. But you don’t want to damage also your health in the longer run.”

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Associated Press reporter Alexa St. John contributed from Detroit.

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