Many homes survived the fires in Altadena and Palisades in January 2025 with little to no burn damage. However, dense smoke and ash from the fires penetrated homes through a variety of places, including HVAC systems, open windows, and even walls. When the smoke cleared, toxins and residue were left behind.

Unlike forest fires, wildfires that take place in the “wildland-urban interface” (WUI) create smoke that contains toxic chemicals due to the types of fuel that are burned: cars, trucks, batteries, industrial sites, homes painted with lead paint, and other structures.

The below resource is intended to summarize these finding to help inform post-fire remediation and public health recommendations.