Source Attribution and Health Burden of PM_2.5 in Mainland Thailand

PM_2.5 is a critical air pollutant that significantly impacts human health and the environment. To develop effective air quality management and mitigation strategies, understanding PM_2.5 source attribution and associated health risks is essential. This study investigates the source attribution and health burden of PM_2.5 focusing on Mainland Thailand (MT), North Thailand (NT), and the Bangkok Metropolitan Region (BMR), using the WRF-Chem model and a brute-force method for source attribution. PM_2.5 contributions from biomass burning including both crop and non-crop burning are quantified, along with contributions from transportation, industry, energy, residential, and other anthropogenic sectors. This study focuses on the haze season (February-April) in 2019. Our research shows that in-domain foreign country's biomass burning is a major contributor to PM_2.5, accounting for 23%-38% of PM_2.5 concentrations in MT. In NT, non-crop burning within MT contributes the most (21%-36%) to PM_2.5 levels, while crop burning within MT has a minimal impact (less than 6%). In the BMR, PM_2.5 is strongly impacted by sources outside the model domain. Overall, industrial and transportation emissions are the most impactful anthropogenic sources. We further estimate the total health burden, associated with long-term PM_2.5 exposure during the haze season contributes to 46% of this PM_2.5 health burden in MT in 2019, 66% in NT, and 37% in the BMR. These findings suggest that reducing biomass burning within MT and from in-domain foreign countries during February-April could reduce the annual health burden in MT by up to 20%.