Caltech Study: Los Angeles Eaton Fire Smoke Carried More Than 50 Times the Lead of Wildfire Smoke, With Nearly 7 Million People Exposed to 80 Times Typical Lead Levels
Caltech scientists reported on October 28 in the journal Science Advances that during the January 2025 Eaton Fire, lead levels in Los Angeles urban smoke were more than 50 times those in ordinary wildfire smoke. During the phase of most intense building burning, nearly 7 million people across the Los Angeles metropolitan area were exposed within 24 hours to lead concentrations 80 times typical levels. The study was led by doctoral researcher Haroula Baliaka, with co-author Ryan Ward and corresponding authors Professor Nga Lee "Sally" Ng and Professor Richard Flagan (DOI: 10.1126/sciadv.aei4455).
The team sampled air at a monitoring station in Pico Rivera, about 11 miles south of Altadena, one of 12 stations in the ASCENT network. Chlorine and bromine in the urban smoke measured about seven times wildfire-smoke levels, and arsenic about three times. The comparison case was the September 2024 Airport Fire in Riverside County, which burned 24,000 acres of vegetation. Tracking the potassium-to-lead ratio, the researchers found it was about 5 to 1 on January 8-9, about 50 to 1 on January 11, and rose to hundreds to 1 by January 12, showing the share of building-derived lead falling as structural burning subsided.
The researchers said the actual health effects of this lead exposure remain unclear and require further study. Their central finding is that urban smoke from the Eaton Fire differed fundamentally from vegetation wildfire smoke, because what burned was an entire community's buildings and contents.
The Eaton Fire was among the most destructive of the January 2025 Los Angeles fires, destroying more than 9,000 structures, killing 19 people and forcing more than 100,000 residents to evacuate.
Related: LA County | Eaton Fire-Destroyed Altadena Park Breaks Ground on Rebuild
Source: GSM · USA (original Chinese edition)
Photo: 图：伊顿火灾之后的阿尔塔迪纳乡村俱乐部（Altadena Town and Country Club）景象，为火灾后建筑残骸、非烟雾实测现场。洛杉矶县政府摄，公共领域，经 Wikimedia Commons。 / The Altadena Town and Country Club after the Eaton Fire; post-fire structural damage, not a smoke measurement site. Los Angeles County photo, public domain, via Wikimedia Commons.
