Post-Wildfire Indoor Pollution in WUI Areas: Establishing Baseline Contaminant Levels Before Home Reoccupation
EHSAN GOFTARI, Hanyang Li, San Diego State University
Abstract Number: 191
Working Group: Burning Questions of Aerosol Emissions, Chemistry, and Impacts from Wildland-Urban Interface (WUI) Fires
Abstract
As urban areas continue to expand, more people are living in or near wildland regions, known as the Wildland-Urban Interface (WUI), which has significantly increased communities’ exposure to WUI fire hazards. To characterize toxic emissions and environmental concentrations in homes impacted by the 2025 WUI fires in Los Angeles (Eaton and Palisades fires), we performed a combination of indoor air quality measurements of particulate matter, black carbon, total volatile organic compounds, speciated toxic metal particulates using TARTA, and outdoor PM concentrations, as well as collecting wipe samples from indoor floors and surfaces contaminated with ash and soot. Following the fire, the homes located next to a burned structure had higher indoor concentrations of PM2.5 (average of 6.48 μg/m3), PM10 (average of 102.86 μg/m3), and black carbon (average of 774 ng/m3) than homes farther away from the fire or those that had been professionally cleaned. In terms of airborne metals, the average indoor concentrations of iron and copper over all the sampled homes were 60.59 and 3.92 ng/m³, respectively. Most metals were either below U.S. EPA reference inhalation concentrations or below the detection limits of our instrument. While airborne metal levels were not high, the wipe samples revealed elevated concentrations of toxic metals, especially lead. In 75% of sampled homes, surface lead levels were above the EPA’s safety limit of 5 μg/ft². These findings offer important data as indoor dust particles can be resuspended and become airborne during cleaning and remediation activities and pose risks to human health. The current phase of this study involves distribution of nearly 150 Airthings indoor PM sensors to the homeowners in fire-affected areas to continuously examine air pollutant dynamics throughout the post-fire recovery timeline during re-entry and reconstruction, as well as the long-term persistence of indoor contamination.