A multi-platform validation of biomass burning emissions: Integrating ground, airborne, and satellite data to quantify regional haze health impacts in Thailand

초록

Quantitatively linking regional biomass burning (BB) to ground-level air quality remains a persistent scientific challenge in Southeast Asia, where meteorological interference often decouples satellite observations from surface impacts. This study bridges this gap by integrating ground-based PM2.5 monitoring, satellite-derived active fires (hotspots), and in-situ airborne measurements of five chemical tracers (levoglucosan, HCN, CO, OA, and CH3CN) alongside total PM1.5 from the NASA DC-8 ASIA-AQ mission. Focusing on the March 2024 intensive haze episode, we identified a 160-km 'regional airshed' where surface PM2.5 strongly correlated with hotspots (r = 0.69, p < 0.01). Vertical coupling was validated through significant correlations between ground-level PM2.5 and these six in-situ airborne markers (r = 0.64-0.85, p < 0.01), supporting the interpretation that surface haze is associated with smoke plumes. Source apportionment utilizing topographical scaling (factor of 4 to scale between lofted and surface smoke) and degradation-corrected emission ratios (to account for photochemical loss of levoglucosan) revealed that standard 'fresh' models without these corrections severely underestimated BB contributions (yielding 5.40%). By establishing boundary limits, an 'aged' tracer scenario (lower limit) and bulk organic aerosol mass (upper limit) demonstrated that regional smoke contributed 52% to more than 100% of Northern Thailand's PM2.5, imposing an absolute burden of 35-90 mu g/m(3). Health impact assessments (WHO HRAPIE-2) estimated a theoretical short-term excess mortality risk ranging from 3.81% to a critical maximum of 9.12% during peak episodes. However, mass-based metrics likely underestimate true health impacts, given the cumulative exposure to chemically complex, carcinogenic aerosols. These findings highlight the disproportionate absolute health burden in Northern Thailand and emphasize the urgent need for integrated transboundary governance.

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