Urban wildfire smoke contained high levels of lead and arsenic

The smoke plume from the urban Eaton Fire in Los Angeles exposed millions of residents to high levels of toxic chemical compounds, Eos reported. According to research published in Science Advances, smoke from the January 2025 fire contained 50 times as much lead, seven times the halogens, and three times as much arsenic compared to smoke from a nonurban wildfire that primarily burned vegetation. [1]

Michael Kleeman, a civil and environmental engineer at the University of California, Davis, who was not involved in the study, noted the significance of these measurements in an email to Eos. The burning of synthetic materials and urban structures contributed to the distinct cocktail of chemicals detected in the atmosphere. [1]

The Eaton Fire killed 19 people, forced the evacuation of more than 100,000 residents, and destroyed upward of 9,000 structures, Eos reported. High winds and dry weather conditions fueled multiple destructive wildfires across the Los Angeles area during January 2025. [1][3]

Overall, 14 wildfires affected Southern California that month, burning more than 57,529 acres, driving over 200,000 total evacuations, and destroying around 20,000 structures across the region. [3]