SANTA MONICA—On January 2, 2026, the University of California, Los Angeles Fielding School of Public Health released the results of a study that found a year after the California wildfires, smoke damage lingered indoors.
Some of the people who conducted the study were Dr. Yifang Zhu, Dr. Yuan Yao, Dr. Michael Jerret, and Dr. Haoxuan Chen. It is titled “Indoor and Outdoor Volatile Organic Compound Levels during and after the 2025 Los Angeles Wildfires” and was published in the journal Environmental Science & Technology.
Scholars began collecting air samples on January 8, 2025, and continued until February 18, 2025. While doing so, they tracked the movement of volatile organic compounds, including toluene, n-hexane, and benzene, and they found that the amount of benzene in the air was greater weeks after the fire started and that the amount of some of the compounds they were tracking some including toluene and n-hexane, peaked either during the later stages of the fire burned or after the fire stopped burning. In addition, they found that levels present indoors and outdoors exceeded those recorded at the start of the wildfires.
The chemicals pose health risks and cause cancer and can also negatively affect the nervous system and the eyes and the liver. At risk are children, pregnant women and the elderly.
Scholars who conducted this study recommend that those returning to their homes in affected areas should undertake efforts to improve the ventilation in their homes by opening windows. When possible, make use of ventilation systems, that include either MERV-13 or higher-rated filters. In addition, they also recommend that residents run portable HEPA air cleaners that included activated carbon filters. Scholars suggest that dust and ash should be removed by using wet methods or HEPA-filtered vacuums.
By Daniel Diquinzio