Overview
- The peer-reviewed study, published in June 2026, analyzed air samples taken about two months after the January 2025 Palisades and Eaton fires and found airborne hexavalent chromium nanoparticles in and downwind of cleanup areas.
- Researchers reported an average chromium‑6 concentration of 13.7 nanograms per cubic meter, a level below federal workplace limits but above U.S. EPA screening thresholds for indoor air.
- Wind-transport modeling indicates the particles likely traveled six to nine miles downwind and could have delivered elevated doses to as many as 3.3 million people in Los Angeles communities such as Beverly Hills, West Hollywood and parts of the San Fernando Valley.
- The team observed chromium‑6 concentrations decline over time as the compound reduced to the less toxic chromium‑3 and returned to background roughly eight months after the fires, which narrows the main window of elevated risk.
- Authors recommend continued air monitoring near cleanup zones and immediate steps for residents such as using indoor air filters and limiting heavy outdoor activity during cleanup; the findings also highlight broader risks from wildland-urban fires that mix toxic metals into debris and smoke.