University researchers warn of long-term health risks from untested wildfire soil

A group of university researchers is urging Gov. Gavin Newsom to restore California’s wildfire recovery protocols by funding comprehensive soil testing in Los Angeles County neighborhoods impacted by the recent Eaton and Palisades wildfires. They warn that failure to do so could pose long-term health risks to returning residents.

In a letter sent to Newsom and California Environmental Protection Agency Secretary Yana Garcia, nearly a dozen environmental health and engineering professors from institutions, including the University of Southern California and the University of California, L.A., expressed concern that thousands of properties destroyed by the fires are being cleared for rebuilding without soil testing to identify toxic contaminants that may remain after debris removal.

“At present, no parcel-specific soil testing is required or recommended by the State for residential properties impacted by the Eaton Fire and Palisades Fire,” the researchers wrote. “In our view, this poses a serious risk to public health and the economic recovery of the communities.”

Post-wildfire environments are often contaminated with heavy metals and other hazardous substances, including lead, arsenic, and polycyclic aromatic hydrocarbons (PAHs), which can remain in the soil even after visible debris is removed. Lead and arsenic, in particular, are known to pose risks to children and pregnant women, even at low levels, according to the L.A. County Public Health.

Local testing efforts have already identified the cause of concern. Soil samples collected by the Los Angeles Times in collaboration with the L.A. County Department of Public Health found elevated levels of lead and arsenic in several cleared parcels in Altadena.

Andrew Whelton, a Purdue University environmental engineer who has led post-fire contamination assessments across the U.S., emphasized the importance of robust testing in ensuring safety.

“The decision not to conduct soil testing the way it has been in the past — without any advanced warning — has really thrown personal safety and the ability of the community to rapidly recover up in the air,” Whelton said.

Historically, California disaster recovery protocols have included soil testing after federal crews complete debris removal, especially at homes destroyed in wildfires. When contaminant levels exceeded the state’s residential soil safety standards, cleanup crews were ordered to return and excavate additional soil layers. This approach was implemented after past wildfires like the 2018 Camp Fire, where state officials determined soil testing was critical to avoid long-term exposure to toxic metals.

Currently, the U.S. Army Corps of Engineers and the Federal Emergency Management Agency (FEMA), which are managing debris cleanup in L.A. County, are removing ash and up to 6 inches of topsoil but are not conducting chemical testing unless requested by local authorities. FEMA has rejected state requests to pay for broader soil testing, claiming its removal procedures adequately mitigate immediate risks.

“FEMA’s refusal to test for toxins in the soil after wildfire cleanup in Los Angeles County is unacceptable,” said U.S. Congresswoman Laura Friedman (CA-30). “Families deserve to know their homes are safe and free of dangerous chemicals. This is a break from decades of FEMA precedent — and it risks exposing entire communities to long-term health threats.” 

Nefretiri Cooley, spokesperson for the California Environmental Protection Agency, said the state continues to advocate for more extensive testing.

“The State continues to push for our federal partners to conduct comprehensive soil sampling as part of the debris removal process,” Cooley said.

So far, approximately 4,700 of the more than 10,000 properties signed up for cleanup have been cleared and deemed eligible for rebuilding permits without soil testing. 

“Residents impacted by wildfires and other disasters need to know that their properties are cleaned-up, free from harmful toxins, and safe for rebuilding,” said U.S. Congresswoman Julia Brownley (CA-26). “Recent changes to FEMA’s procedures, forgoing soil testing in favor of across-the-board topsoil removal, have left many in the community concerned about possible hazards. It is important for federal, state, and local governments to work together to address these concerns and ensure Californians are confident that public health is fully protected.” 

To help fill the gap, the L.A. County Health Department has allocated $3 million to fund testing for residents exposed to wildfire smoke and ash. However, Whelton noted that this approach falls short, as it typically involves only one soil sample submitted by a homeowner without expert interpretation.

“One soil sample will be analyzed that a homeowner submits to a commercial laboratory, and then the homeowner will have to interpret the data on their own,” he said. “So that is not going to get people [back] to safe properties again.”

Experts also warned that abandoning soil testing could have broader implications for fire-prone regions across California, where about 30% of residents live in high-risk zones. Without clear protocols, future wildfire recovery efforts could expose thousands to hazardous materials buried in the soil.

“Because there was an abrupt decision by multiple government agencies to just not do it, that’s left a whole bunch of property owners with anxiety and an unclear path to how they are going to make their property safe again — or if they want to return,” Whelton said.

As rebuilding efforts ramp up, with new programs allowing architects and engineers to “self-certify” building code compliance using artificial intelligence tools, experts caution that expedited permitting must not come at the cost of environmental safety.

With federal support ruled out, researchers are pressing the Newsom administration to uphold the state’s long-standing commitment to comprehensive, science-based wildfire recovery — starting with the soil beneath residents’ feet.