Even after the disastrous L.A. wildfires abated last year, the danger from smoke persisted for many people living nearby. A new study finds that, by some measures, indoor air pollution actually worsened after the fires.
Erupting in January 2025, the Palisades and Eaton fires burned through large areas of Los Angeles, damaged or destroyed more than 18,000 buildings and, by one estimate, killed 440 people. To track pollution from the fires, researchers at UCLA collected air samples across the city, both indoors and out, throughout January as the fires burned and in the weeks that followed.
The researchers tracked levels of volatile organic compounds, or VOCs, unleashed by the burning of paint, carpets, upholstery, and other materials commonly found in homes. “Some of these are carcinogenic and definitely harmful to human health,” said coauthor Yifang Zhu, of UCLA.
Researchers found that while outdoor VOC levels dropped after the fires were extinguished, indoor levels of some compounds rose. The reason, they speculate, is that homes that were blanketed in smoke continued to release VOCs into the air. The study was published in the journal Environmental Science & Technology.
“Even after wildfires are extinguished, residents may remain at risk of exposure to indoor VOCs,” Zhu said. To clear the air, experts recommend that affected homeowners open windows and run heaters or air conditioners.
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