UCLA scientists expand soil testing after being influenced by soil contamination issues raised by fire survivors in Altadena, Pasadena, Palisades.
Igor Bronz, left, a volunteer with TreePeople, and Kirsten Schwarz, associate professor in the UCLA Fielding Schools Department of Environmental Health Sciences, work together on clean soil samples at the March 7 free soil testing event in Watts.
It surrounds people’s homes. It’s in local parks, schoolyards and parkways abutting sidewalks. But it’s not something people paid much attention to.Ever since the Palisades and Eaton fires in January 2025 burned out more than 16,000 structures, mostly homes, leaving piles of charred rubble behind often with lead-contaminated ash, dirt has become big news. Once this debris was removed and sent to landfills, the focus shifted downward to the lot’s remaining dirt.Many fire survivors, both those with cleared lots, and displaced survivors with standing homes infiltrated by smoke and ash, say the government has not supplied clear answers to that question. And insurance companies have not provided the money for remediation of dirt laced with high amounts of lead that tests above state safety levels and in some cases, higher than the more lenient federal standard. You could say dirt is what is literally standing in the way of fire survivors re-building. And stopping those from returning to vacant homes. While the Environmental Protection Agency in January announced additional testing, and Los Angeles County sprung for more soil testing, this hasn’t touched all homeowners. Enter the scientists with the UCLA Fielding School’s Department of Environmental Health Sciences and a group they formed to yes, test dirt, what they call soil, called the LA Urban Soil Social Impact Collaborative.. In short, many regions in Los Angeles County and all across Southern California have been dealing with lead and other toxic metals in their soil for years, even decades, that are not sourced from fires. “We in Los Angeles especially don’t think about the benefits we get from soils in cities. It is often overlooked,” said Kirsten Schwarz, a UCLA professor in urban planning and environmental health sciences who is a member of the soil collaborative. “People having access to clean soil is important. A lot of urban areas are often compromised,” she said during an interview on March 18. “We are interested in healthy soil, so it is not a harm to people. A lot of focus has been on heavy metal contamination, lead in particular.” During a soil symposium in Los Angeles, a survivor from the Eaton fire zone asked if the collaborative would do soil testing in Altadena, where more than 6,000 homes burned, often older ones with walls covered in lead paint, torching cars with lead-acid batteries as well. The collaborative agreed. Folks brought their yard soil samples to their pop-up at the Grocery Outlet parking lot on Lake Avenue in Altadena. The response was tremendous. And the scientists using hand-held x-ray devices could present results right away to the fire survivors, Schwarz said. UCLA Fielding School of Public Health students Samantha Venegas, Steve Jang and Amelia Najar, and TreePeople intern Bella Jahrmarkt of Scripps College work at the Dec. 6, 2025 soil testing event in Pasadena. . The collaborative held two more events in Altadena and Pasadena, because demand was sky high. They tested 600 samples from 250 residents. “Folks approached us to work in fire-impacted communities because there was such a great need for that; so many people wanted to get their soil tested,” said Schwarz. And these people were more aware of soil contamination issues than in other places they’ve worked. The result? The knowledge from these fire survivors — and their soil data — helped inform the scientists’ soil testing in all regions, functioning as a kind of citizen science component. “The L.A. wildfires highlighted a soil contamination concern that many communities in Los Angeles have been dealing with for a long time, and with attention now on LA’s soil, it’s a good time to advocate for healthy soil solutions,” said Monika Shankar, a UCLA researcher and co-leader of the collaborative. For example, Schwarz said the group usually sees higher levels of lead right next to the house than at the edge of the yard. This could be older lead from repairs and repainting involving sanding down old lead paint, usually not from a fire. Lead dust particles in the air also accumulate and can be intercepted by a structure. Plus lead paint breaks down, dissolving into soil.Helped by a strong media response, the group has not had trouble bringing in community sources for funding and for volunteers. These include: the Centre for Applied Ecological Remediation, Communities for a Better Environment, Laboratory for Indigenous Knowledge Systems, Physicians for Social Responsibility-LA, Laboratory for Indigenous Knowledge Systems, TreePeople, and the Watts Labor Community Action Committee. The collaborative is planning more pop-up soil testing events. The extra amount of testing and responses by the fire-impacted communities also helps the team highlight their main goal, namely, educating people about the importance of clean soil and advancing innovative solutions for cleaning dirty soil. “Soil is good for people,” Schwarz began. “Soil is good for plants, for maintaining green infrastructure projects that need healthy soil to receive the stormwater. And yes, trees need good soil.” Kirsten Schwarz, associate professor in the UCLA Fielding School’s Department of Environmental Health Sciences, leads the LA Urban Soil Social Impact Collaborative, a community-university partnership that is providing free soil testing in neighborhoods across Los Angeles County. .Lead can be a public health threat, depending on the concentration and the duration of exposure. It can enter the body from ingestion, from lead pipes delivering water, or from inhalation of lead dust from the air or industrial processes. The EPA reports that lead can cause behavioral programs, learning disabilities and seizures. Children under six years of age are most at risk because they can eat chips of lead paint or put their hands in their mouths after playing in contaminated dirt. They can suffer from lowered IQs, slowed growth, damaged to the brain and nervous system and headaches. In adults, high levels of lead exposure can cause reproductive problems in both men and women, high blood pressure, nerve disorders, memory and concentration issues and muscle and joint pain. Concerns about lead in their front and back yards have prevented Karen Walker and her family from moving back to their Altadena home, located near the Altadena Golf Course.Lead levels above 80 parts per million can be a health concern, according to the state. The federal safety level is higher, at 200 ppm. Tests of soil from the Walker home for lead reached 100 one time, 80 the next time, she said, causing concerns. Her home’s landscaping is intact: with green carpets of St. Augustine grass and other permanent landscaping intact, she said. This complicates the problem. Replacing all the landscaping and removing the contaminated soil beneath will cost about $40,000, she said. While doing nothing is cheap, but presents too many safety unknowns. “We enjoy outdoor parties, egg hunts, croquet games and on Fourth of July just sitting on the lawn with the dogs and watching fireworks,” she said. These are activities she believes are no longer safe for her family in the Altadena house. “I don’t think anyone wants to lay in a bed of lead and asbestos,” she said. The collaborative advocates a less-costly solution: Using clean dirt collected from construction sites, compost or mulch or a combination to apply to contaminated yards. By mixing in the clean dirt, it lowers the concentration of lead in the soil and reduces the risks of exposure, the collaborative reported. Or, property owners can lay a thick cover of clean dirt atop their property, creating a barrier between contaminated soil and people, Schwarz said. “Adding clean soil to contaminated soil can have a dilution effect,” she explained. “These are the kinds of solutions we are very excited about.” Many in fire zones are concerned that lead in the dirt can affect vegetables grown for food in home gardens. Schwarz said most plants are not good at taking up lead from the soil, because lead is bound to the soil particles. “The bigger concern is the soil itself and making sure you protect yourself,” she said. Several tests on soil in the yard of Claire Thompson’s vacant house in West Altadena came up with PPM levels of lead at: 234, 190, 122-126 and 140. All of these are above the state standard. She said soil removal and taking it to an appropriate landfill will cost $80,000 to $100,000, which will not be paid for by her insurance. She’s not informed about the soil capping alternative, she said. “It would give me more peace of mind if I removed the soil and replaced it with clean soil,” she said. “Soil is a very important issue.” The collaborative has been collecting clean, excavated dirt and mixing it with local compost to create a healthy soil source that can be used for restoration of fire sites, a process they call soil banking. TreePeople, an environmental group partnering with UCLA, found that Los Angeles County produces more than 160,000 tons of clean, native sediment each year from construction projects. “If we can find a way, we can distribute this material to folks who are concerned about their soil,” Schwarz said. “It is a low-cost way to reduce potential risk.” Experts weigh in on complex restoration of fire-damaged Eaton Canyon park and replacing nature centerPhilippe the Original ends a tradition while another century-old restaurant closesJudge rules to evict iconic Olvera Street donkey stand, opened in 1968Ex-LAUSD employee, tech vendor charged in alleged $22 million contracting schemeUCLA faces questions after falling short of the Sweet 16Oscars will move from Hollywood to L.A. Live in downtown Los Angeles in 2029
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