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.