In a new study on the impact of the 2025 wildfires in Los Angeles County, a research team led by scientists from UCLA's Fielding School of Public Health found that even after the fires are extinguished, residents returning to their homes may still be exposed to carcinogens (a known cancer-causing substance) due to smoke damage.

In the peer-reviewed study, titled “Indoor and Outdoor Volatile Organic Compound Levels During and After the 2025 Los Angeles Wildfires,” researchers found that, compared to the period when the fire was active, levels of some volatile organic compounds (VOCs) were significantly higher in the post-fire period and were particularly evident in unoccupied homes within the affected areas, suggesting continued indoor emissions from smoke-affected materials.

“These findings underscore the need for targeted interventions to minimize indoor exposure during the recovery phase,” said Dr. Michael Jerrett, a co-author of the study.

“These findings raise concerns about indoor air quality following wildfires and the potential for prolonged exposure that can lead to significant health impacts,” added Jerrett, holder of the Jonathan Fielding Chair in Climate Change and Public Health at UCLA.

The January 2025 wildfires in Los Angeles County, both in the Pacific Palisades-Malibu area of ??West Los Angeles adjacent to the Santa Monica Mountains, and in the Altadena-Pasadena communities in the foothills of the San Gabriel Mountains, claimed at least 31 lives, burned more than 37,000 acres, and damaged or destroyed more than 18,000 structures, according to county estimates.

Both fires broke out in open areas on January 7. They spread into residential neighborhoods and were not fully contained until January 31.

Researchers began fieldwork on the second day of the fires, collecting indoor and outdoor air samples, and continued throughout the post-fire period, concluding on February 18, 2025.

The team, comprised of UCLA faculty, staff, and students, focused on the prevalence of volatile organic compounds (VOCs), such as benzene, toluene, ethylbenzene, and xylenes (BTEX).

“Some of these compounds are carcinogenic and definitely harmful to human health,” said Dr. Yifang Zhu, a professor in the Department of Environmental Health Sciences and a co-author of the study.

“What made these urban wildfires particularly concerning was the potential toxicity of the resulting smoke, as VOCs are ubiquitous in residential areas, with common sources including building materials and household products such as cooking and cleaning products.”

In addition to benzene, the presence of Other compounds, such as toluene and n-hexane, peaked in the final stage of active combustion, exceeding both pre-fire background levels and, in some cases, levels recorded during the fires, highlighting the risks of remaining in a fire-affected area, the researchers said. “In these cases, indoor concentrations during active fires remained comparable to outdoor levels, indicating that staying indoors did not completely prevent exposure to fire-related contaminants,” said Dr. Yuan Yao, a UCLA Fielding Research Fellow and first author of the study. “This indoor/outdoor pattern changed during the post-fire recovery phase, likely due to the release of gases from smoke-affected materials, highlighting the potential for prolonged indoor VOC exposure, even after outdoor fire activities ceases.” rubble are not giving up and vow to rebuild their homes “no matter what.”

“My dad's goal is to rebuild our house,” said Jesus Hernandez, a newly graduated nurse who was displaced by the Eaton fire to an apartment in Ontario City, along with his wife, Angie Ochoa. Her parents and younger sister, Grecia, live in a small condominium in Pasadena.

Hernandez, 24,He announced that authorities have approved plans to rebuild the Altadena home where he spent his entire childhood, which was completely destroyed on January 7, 2025. The Eaton Fire originated on or near land within the Angeles National Forest in Los Angeles County. It was started due to faulty electrical infrastructure owned by Southern California Edison, the company responsible for its maintenance and operation. The tragedy ravaged nearly 8,000 acres, thousands of homes, and destroyed or damaged roads, trails, campsites, and other Forest Service facilities. In addition to numerous recreational trails, visited by hundreds of thousands of people annually, which were closed due to the fire, the area also suffered from water and air quality issues.

“That day, I was ready to go to school because I had a nursing exam and I couldn't miss it since it was a private school,” recalled Jesus, who has since graduated as a nurse. “Then,my cousin Mariana texted me and told me that Altadena was burning.”

“Are you sure?” I asked. “She told me yes. “I'm just calling to make sure everyone is okay.”

Jesus couldn't believe it. He knew nothing about the fire. He called his mother, Imelda, who didn't answer; then he called his father, and when there was no news, he began to worry.

The family was evacuated at 3:00 am Hours later, they learned that the house had burned down completely.

Jesus and “Don Chuy,” a maintenance worker at a supermarket, went to check. The house was still smoldering. They never found their dog, Buddy. They didn't know where he went either.

The bluish-gray house that the Hernandez family had lived in for more than 20 years, located at 2515 Glenrose Avenue, was gone, and “Don Chuy's” truck was burned to a crisp.

Almost a year after the tragedy, Jesus told La Opinion that he misses the joy that existed back then. house, where weekend parties were a regular occurrence.

“Many people would ask to borrow my dad's house,” he recalled. “There was always music and dancing, and I miss all of that, but I also pray for the people who were injured and for those who died.”

Don Chuy reported that as soon as the plans are approved, they will begin rebuilding the three-bedroom house he bought for $600,000 in 2003, which, according to market prices, would be worth approximately $1.1 million in 2025.

“What hurts me the most is not being able to go out and play in the yard with my granddaughters,” said Don Chuy, 47. “Whenever they visit, they have to stay inside the condominium.”To rebuild his house, this man, born in La Barca, Jalisco, will have to comply with new requirements from the city of Altadena: the installation of sprinklers and solar panels The devastation of the Eaton and Palisades fires caused the death of 31. people: 19 residents of Altadena, five in Pacific Palisades, and seven in Malibu or Topanga Canyon. Some of the victims refused to evacuate when the flames started, others did not realize the danger in time, and still others were too ill to leave their homes and were burned alive: three were approximately 90 years old and nine were at least 80. The power company SoCal Edison acknowledged that its transmission equipment may have been associated with starting the devastating fire that began shortly after 6 pm on January 7, when sparks were detected near high-voltage power lines in Eaton Canyon, in the foothills of the San Gabriel Mountains. The US Department of Justice sued Southern California Edison, alleging that the company's equipment caused the deadly Eaton Fire. Its civil suit seeks reimbursement for the costs of containing the fire and rehabilitating 8,000 burned acres of the Angeles National Forest.

“SCE knew of the potential danger posed by the high winds and the risks posed by the power and transmission lines, but took no steps to prevent a fire from occurring,” the lawsuit states.

Putting out the fire, the department said in the lawsuit, cost more than $40 million and the damage will require a substantial effort to rehabilitate.

In support of its claim that the fire was caused by utility equipment, the Justice Department cited public statements made by Pedro Pizarro, executive director of the parent utility, including a January statement in which Pizarro said that, without further evidence, “we believe SCE equipment could have been associated with the fire.”

East of Mendocino Street and the intersection with Holliston Avenue, John Jackson fondly stroked his sago palm, a showy evergreen plant native to tropical and subtropical regions.

“I have my plant for “More than 50 years and I've seen it reborn. It's what I love most,” the 80-year-old African American man said nostalgically. Jackson, a single university professor who now lives in Monterey Park, said he doesn't plan to sell his property. “I'm going to renovate it,” he said. “Whatever it costs.” Mitigation Measures: Mitigation measures may include opening windows regularly, Use heating, ventilation, and air conditioning (HVAC) systems with filters rated at least at the Minimum Efficiency Rating (MERV) 13, and use portable high-efficiency particulate air (HEPA) purifiers with activated carbon filters when available. The data makes it clear that anyone living or working in fire-affected areas, from firefighters to residents and construction workers, needs to understand the risks, according to the “Even after wildfires are extinguished, residents may still be exposed to VOCs indoors,” Zhu said. “This pattern suggests that smoke-affected materials inside the home could continue to release VOCs into the indoor environment, creating a source of prolonged exposure. To reduce these risks, residents returning to their affected homes should take steps to improve ventilation and filtration.”

That's precisely what Castaneda and Ernesto Uriel did, installing a new ventilation system at 2392 Marengo Street in Altadena over the past two weeks.

“We have no problem breathing here,” Carlos told La Opinion “I think the air has completely cleared up in this area.”