After flames swept through Los Angeles’ Pacific Palisades and Altadena neighborhoods in January, many residents returned to damaged or destroyed homes, blackened hillsides and an invisible hazard beneath their feet: toxic soil.

Ash and debris from burned buildings can release heavy metals and chemicals that linger long after the flames are out. For families hoping to rebuild, the risk is more than structural. It’s about the safety of their yards, their children and their pets.

USC Dornsife scientists quickly mobilized. “After the fires, we immediately began testing soil for lead,” says Seth John, associate professor of Earth sciences. “We soon realized there was a tremendous need for residents — and business owners — to have a reliable, affordable way to check their own properties for contamination.”

With backing from USC Dornsife Public Exchange and in collaboration with the Keck School of Medicine of USC, the team created Containment Level Evaluation and Analysis for Neighborhoods (CLEAN). The program offers free soil testing, filling a critical gap created when government aid falls short and private testing proves costly.

Collection boxes were placed across burned neighborhoods. “We were inundated — we couldn’t test samples fast enough,” says project co-lead Sam Silva, assistant professor of Earth sciences.

In June, a $1 million gift from FireAid expanded CLEAN’s reach. The program now screens for multiple contaminants and can process samples more efficiently, helping more families and businesses in need.

“This work lays the foundation for how scientists can respond to environmental crises,” says project co-lead Josh West, professor of Earth sciences and environmental studies. “It demonstrates what research universities can do when communities are at their most vulnerable.”