High-Resolution Residential Biomass Emission Inventories for Sustainable Air Quality Management: Source-Side Hotspot Identification and Mitigation Targeting in Southern Chile

Residential biomass combustion is a major emission source in southern Chile, but aggregated inventories provide limited support for geographically targeted management. This study developed a high-resolution census-block source inventory for urban Temuco and Padre Las Casas by combining 2024 Census household counts by main heating fuel with solid volume consumption, species-specific basic densities, and emission factors. Annual total particulate matter (PMTotal) and carbon monoxide (CO) emissions were estimated across 4434 census blocks. Twenty-seven deterministic combinations of firewood volume, species-matched density and emission-factor settings, and paired emission-factor levels were evaluated for the baseline inventory using Gini coefficients, upper-tail emission shares, and hotspot persistence. A first-order occupancy-gradient sensitivity test and complete, spatially targeted, and proportional mitigation scenarios were evaluated separately using the fixed reference benchmark. Under the reference benchmark, annual emissions were 251.57 t yr−1 of PMTotal and 14,508.92 t yr−1 of CO; firewood contributed 86.66% and 93.91%, respectively. Across the contextual factorial, PMTotal ranged from 178.95 to 2044.04 t yr−1 and CO from 10,112.56 to 126,271.65 t yr−1. Despite this magnitude sensitivity, 330 PMTotal and 319 CO P90 source-side hotspots, defined as census blocks with emissions at or above the 90th percentile of the corresponding spatial distribution, persisted across all combinations. The occupancy gradient increased the Gini coefficient by approximately 0.008 while retaining more than 90% of each highest-emitting decile. Complete firewood-to-pellet transition reduced PMTotal by 57.56% and CO by 80.64%. At the top-20% intervention level, targeted and proportional allocation produced identical aggregate reductions, but targeting retained only 16.82% and 2.03% of baseline PMTotal and CO P90 hotspots, compared with 48.21% and 36.49% under proportional allocation. These source-side hotspots identify where emissions originate, not where pollutants accumulate. The framework supports geographically differentiated residential-heating policies and future atmospheric modelling.