Free lead soil testing by USC Dornsife researchers helps L.A. residents after wildfires

In the wake of January’s wildfires, Los Angeles residents are dealing with a new danger: toxic lead contamination in their soil. The fires burned through thousands of older buildings — many coated with lead-based paint — raising concerns about heavy metal-laden ash settling in neighborhoods.

Despite the risks, federal agencies have opted not to test soil after removing debris and topsoil from burned areas. That leaves homeowners, businesses and schools responsible for covering the cost of testing soil on their properties.

Public Exchange, based at the USC Dornsife College of Letters, Arts and Sciences, has launched a community-driven effort to fill the gap. Through its Contaminant Level Evaluation & Analysis for Neighborhoods (CLEAN) project, the team invites L.A. County residents to submit soil samples from the burn areas — at no cost — for analysis by experts from USC Dornsife’s Department of Earth Sciences. The goal: determine whether lead levels pose a health risk.

“The initiative aims to quickly identify potential environmental hazards like lead left by these fires,” said Josh West,professor of Earth sciences and environmental studies at USC Dornsife. “With the Army Corps skipping post-cleanup soil testing, there’s a lot of uncertainty. Data will be key to protecting health and determining next steps,” he added.

Early findings from wildfire soil testing ease concerns

Lead, a toxic metal that poses serious health risks, is especially dangerous to children, as even small amounts can impair brain development. “The fires in Los Angeles have raised alarms about potential contamination in both immediate burn zones and the surrounding areas,” said Erika Garcia, assistant professor of population and public health sciences at Keck School of Medicine of USC, who is advising on the project.

Preliminary testing by USC Dornsife scientists in February found that lead levels were highest in the burn areas of the Palisades and Altadena and decreased farther away from these zones. Still, most samples — even those collected in the burn zones — showed lead concentrations comparable to those found in many urban areas, including downtown L.A.

In some locations affected by the Eaton Fire, where approximately 9,000 structures burned, roadside dust exceeded the Environmental Protection Agency’s (EPA) current screening level of 200 parts per million (ppm) for residential soil. (In January 2024, the EPA lowered the threshold from 400 ppm to 200 ppm in areas where children play.) Nearly all post-fire soil samples from Altadena and the Palisades would have met the old standard.

“We were relieved to find that the levels in and around the burn zones, while above the updated EPA standards, were still within the range found elsewhere in the city,” said Sam Silva, assistant professor of Earth sciences, civil and environmental engineering and population and public health sciences. “We were expecting much higher rates.”

Free wildfire soil testing for residents

Residents can drop off soil samples at designated collection sites in Pacific Palisades, Santa Monica and Altadena or mail them directly to USC researchers.

In the future, researchers hope to add more collection sites and capacity to screen for additional hazardous substances, including arsenic and other contaminants.

Test results will be available within one to two weeks, depending on submission volume. Anonymized results will be posted on a public Google Sheet, and each participant will receive a unique identification number to access their results. The findings will also appear on an interactive map showing sample locations and lead concentrations across affected areas.

“Being able to identify areas where more in-depth investigation is needed arms residents with data to more effectively advocate for further research or support for their communities,” said Seth John, associate professor of Earth sciences.

USC Dornsife’s free soil testing program is intended as a first step in assessing potential risks. It does not replace assessments conducted by private environmental remediation experts or meet state and federal regulatory compliance requirements

For sample collection guidelines and drop-off locations, visit the Public Exchange website.