A team of UCLA researchers has screened nearly 700 soil samples for hundreds of Los Angeles County residents concerned about contamination in their yards and gardens, part of a growing effort to address pollution from both the January wildfires and decades of industrial activity.
The initiative, called the LA Urban Soil Social Impact Collaborative, is a community-university partnership funded by UCLA's Center for Community Engagement. On March 7, researchers held a testing event at MudTown Farms in the Watts neighborhood, screening samples for legacy contamination from nearby industrial land use.
The event was co-sponsored by the Watts Labor Community Action Committee, which manages the farm and community gardening program.
"Soil screening is a necessary first step, but it's not a solution," said Dr. Kirsten Schwarz, associate professor in UCLA's Fielding School of Public Health and a leader of the collaborative. "Whether folks are concerned about soil quality because they are growing fruits and vegetables at home or they're concerned about exposure from their kids playing in the yard, residents of all these communities are eager for knowledge and actionable solutions."
The Watts event was the fourth in a series of field days across the county. The previous three were held in communities devastated by the January wildfires, which swept through the Pacific Palisades-Malibu area and the Altadena-Pasadena foothills. The blazes claimed at least 31 lives and damaged or destroyed more than 18,000 structures, according to Los Angeles County officials.
"After the Eaton Fire, so many residents were left wondering what was in their soil—what they were walking on, planting in, and breathing around their homes," said Kristy Brauch, a master gardener from Pasadena who works with the project. "There's a real mix of fear and urgency, but also an incredible desire to understand and take action."
While the wildfires and industrial activity represent distinct contamination sources, Schwarz said the underlying problem is often the same: lead that has accumulated in soil over generations.
"In older residential areas it's not uncommon to see elevated levels of lead in soil," Schwarz said. "We have increased the amount of lead in soil through our past use of leaded fuel, lead-based paints, and industrial activity."
Lead levels tend to be higher near homes due to deteriorating paint and accumulated particulates, she said—a pattern that holds true in both fire-impacted communities like Altadena and industry-impacted neighborhoods like Watts.
"The LA wildfires and industry can create additional sources of lead that are superimposed on those legacy sources, potentially contributing to elevated soil lead concentrations," Schwarz said.
So far, the team has tested almost 700 samples for roughly 300 residents across the county, including events in Pasadena in October and December.
Researchers use portable X-ray fluorescence analyzers to detect heavy metals, including lead. Participants can have up to three soil samples screened at each event and receive personalized consultations on improving soil health and safety.
The portable devices are not as accurate as laboratory analysis but provide effective screening for potential contamination, Schwarz said. However, they cannot detect organic contaminants such as PAHs.
For residents who discover elevated lead levels, solutions include controlling dust, keeping yards planted, and adding clean soil, compost, and mulch.
"Covering contaminated soil with clean soil, compost, or mulch is an accessible, low-cost way to reduce exposure," Schwarz said. "It creates a barrier between potentially contaminated soil and people."
Because lead does not break down and elevated levels are widespread, she said soil banking and composting represent system-level solutions that could address the problem at scale.
The collaborative includes researchers from across UCLA and Los Angeles-based organizations, including the nonprofit TreePeople. Schwarz co-leads the effort with Dr. Jennifer Jay, professor of civil and environmental engineering at UCLA.
"Addressing soil pollution in Los Angeles and beyond requires community-engaged approaches that center local knowledge and priorities," said Monika Shankar, a doctoral candidate at UCLA's Fielding School and a principal investigator on the project. "Our collaborative serves as a proof of concept that meaningful and impactful research emerges when communities are partners throughout the entire process."
"These testing events meet people where they are, transforming worry into knowledge," Brauch said. "The response has been overwhelmingly positive; my neighbors are already asking when the next one will be."
The collaborative plans to host additional pop-up soil testing events, workshops, and remediation projects across the region.