Assessment of biomass-burning types and transport over Thailand and the associated health risks

Biomass-burning (BB) related air pollution is a prime concern in several regions of the world including Southeast Asia. This study aimed to identify and apportion the BB types (agricultural, forest, and grassland) and assess the transport of BB-derived PM 2.5 which influences the air quality index (AQI) of three major regions (i.e., central, north, and northeast) in Thailand by integrating satellite fire products, air-mass trajectories, ground-based measurements, statistical approaches, and modeling tools. We accounted for the transport time of PM 2.5 from source to monitoring stations by grouping the BB type with air-mass trajectory timestamps. Forest fire predominated over the north (73%) and northeast (48%) whereas agricultural burning predominated over the central (52%) region. Grassland burning was most influential in the central region (16%) followed by the northeast (11%) and north (5%) regions in Thailand. Annual PM 2.5 exposure amounted to very-unhealthy to hazardous PM 2.5 -AQI levels for about 79% of the Thailand population. PM 2.5 -AQI levels over Thailand were mainly governed by transboundary BB influence (67%) whereas the local contribution was about 33%. Excess numbers of premature deaths due to PM 2.5 exposure totaled 18,003, and were associated with stroke burden (53%), ischemic heart disease (30%), lung cancer (12%), and chronic obstructive pulmonary disease (5%), based on public-health data from 2016. The spatial distribution results of excess mortality showed the largest burden in the central region (44%) followed by the northeast (29%), north (18%), and south (9%). Our study results are useful for shaping effective control strategies of open burning management in Thailand and other nearby countries in peninsular Southeast Asia. • PM 2.5 pollution level over Thailand depends on region, season, and BB source type. • Satellite fire and land-use products together with BTs are used to apportion BB types. • Forest fire predominated in the north (73%) and northeast (48%) region. • Agricultural burning was the predominate in central Thailand (52%). • Total premature deaths associated with PM 2.5 exposure was 18,003 deaths in 2016.