Millions of Los Angeles residents were exposed to a toxic cocktail of lead and other dangerous metals during the devastating 2025 Eaton Fire, with lead concentrations soaring to 80 times normal levels, a new study has found.

Researchers at Caltech published the findings Wednesday after comparing the chemical makeup of smoke from the inferno with that of a typical wildfire — and found the urban blaze unleashed a far more toxic mix.

“Compared to wildfire smoke, the urban plume was enriched more than 50-fold in lead, 7-fold in halogens, and 3-fold in arsenic, a toxic mixture linked to burning vehicles, electronics, and building materials, a fundamentally different fuel from conventional wildland vegetation,” the research article said.

The findings highlight the dangers of fires tearing through densely populated areas, where burning homes, cars and electronics can spew hazardous pollutants into the air breathed by millions.

“Unlike wildfire smoke that has been the focus of decades of air quality research, this plume represents an emerging class of urban fire air pollution that demands revised exposure frameworks and emergency response protocols as fires increasingly burn into cities,” the paper added on.

Lead author Haroula Baliaka, a Caltech PhD student, began investigating the problem after setting out to understand why Los Angeles struggles with elevated pollution levels.

Baliaka and co-author Ryan Ward used an air-monitoring system to track pollution around the clock, year-round, collecting data on the chemical makeup of airborne particles through the Atmospheric Science and Chemistry mEasurement NeTwork, or ASCENT.

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“ASCENT has the unique capability to measure the chemical components and the size of these different particles in real time,” Caltech professor Nga Lee “Sally” Ng said.

The Eaton Fire started on January 7, 2025 and ignited at the same time as the Palisades Fire. At least 31 people were killed and over 16,000 structures were destroyed as a result of the two infernos.

Residents were forced to evacuate and most of the businesses in the Pacific Palisades were completely wiped out. Millions of people were exposed to smoke and many even lost their homes.

The newly documented pollution raises additional concerns about the health risks lingering beyond the flames themselves.

High lead exposure can impact the growth of young children and can even be fatal. It can also damage the kidney and nervous systems of anybody regardless of age.