Post-fire soil hazards: recommendations for updated soil testing protocols and clearance thresholds.

Background: Urban wildfires in Los Angeles have highlighted the increased risk of soil lead exposure, especially for children. Current post-wildfire soil remediation protocols may not sufficiently protect public health, especially in communities returning after fire events.

Objective: To evaluate the adequacy of existing soil remediation practices after urban wildfires in Los Angeles and present policy recommendations to reduce lead exposure risk.

Methods: We reviewed current wildfire debris removal protocols, soil testing practices, and health risk benchmarks for lead exposure in California. We assessed recent data from post-fire soil testing and analyzed the scientific rationale underlying California's existing Preliminary Remediation Goal (PRG) for lead in residential soil.

Results: We recommend two critical reforms: requiring post-clearance confirmatory soil testing after wildfire cleanup, as has been done for every major wildfire in California since 2007, and lowering California's residential Preliminary Remediation Goal (PRG) for lead in soil from 80 to 55 mg/kg to reflect updated science and health-protective standards. The basis for these recommendations is that repeated testing after purported soil remediation is showing that greater than 20% of properties still have lead levels that exceed existing thresholds, and the 80 mg/kg PRG (1) does not adhere to the health-based toxicity criterion benchmark set by California, (2) is susceptible to high uncertainty based on the values for several exposure factors used, and (3) does not accurately reflect our current understanding of risks to children from lead.

Impact Statement: This article identifies critical gaps in current post-wildfire remediation protocols that leave Los Angeles residents, especially children, at risk of lead exposure from contaminated soil. By recommending policy reforms including mandatory post-remediation soil testing and a more protective soil lead standard, our work provides an actionable roadmap to strengthen environmental health protections for communities recovering from wildfires. Adoption of these measures will help ensure a safer, healthier future in the face of escalating urban wildfire threats.