Fine Spatial and Temporal Scale Fuel and Emissions Inventories for the Eaton and Palisades Wildland Urban Interface (WUI) Fires

The Eaton and Palisades fires in the Los Angeles area in January 2025 occurred at the Wildland Urban Interface (WUI) consuming structures, vehicles and vegetation. Structures and vehicles accounted for 67% and 62% of the estimated fuel loadings (1.60 × 108 kg and 2.65 × 108 kg), and vegetation accounted for 33% and 38% of the fuel loadings (8.00 × 107 kg and 1.63 × 108 kg) in the Eaton and Palisades burn zones, respectively. Fuel loading inventories were aggregated into 100 m × 100 m grid cells throughout the burn regions, with fuel loadings in individual grid cells ranging from 0 to 2.85 × 104 kg for vegetation and 0 to 1.4 × 106 kg for structures and vehicles. Temporal allocations of the fuel consumed were derived from initiation and duration estimates of the fires based on satellite data, augmented by local reporting. Emissions from the combustion of the fuels were estimated based on multiple emission factor approaches. A base case emission inventory was constructed using average emission factors for structures and vehicles and a widely used tool (Bluesky) for estimating emissions from combustion of vegetation in wildland fires. Alternative emission inventories can be constructed based on more detailed emission factors. As a case study, structures constructed before and after 1978 were given different emission factors for Pb, reflecting different estimated loadings of lead paint based on structure age.