Air quality, health, and economic effects of land use and land cover changes in southeast Asia in the 21st century: a modelling study

Summary Background Southeast Asia has had substantial land use and land cover changes (LULCCs) in recent decades, affecting air quality, human health, and economic development through biogeophysical and biogeochemical cycles. However, little research has examined the combined effects of different LULCC types and impact pathways comprehensively. We aimed to provide a holistic understanding of how LULCCs across southeast Asia in the 21st century have led to changes in air quality and the consequential effects on human health and the economy. Methods In this modelling study, we used a regional meteorology–air quality coupled model (WRF–CMAQ) to assess LULCC effects from 2001 to 2018 on the concentrations of surface PM2·5 and O₃ through biogeophysical and biogeochemical pathways. The model was configured at a 30 × 30 km grid size throughout southeast Asia. We used a series of concentration–response models to estimate excess deaths associated with the changes in air pollution concentration caused by LULCCs. The economic implications of these health effects were quantified with age-specific value-of-statistical-life and cost-of-illness approaches. Findings LULCCs in southeast Asia were associated with 13 000 excess deaths (95% CI 11 000–14 000) in 2018 alone, resulting in US$7·79 billion losses (6·24–9·69). Forest degradation and deforestation was the primary driver, accounting for 29·7% of the burden. Furthermore, more than 60·0% of effects occurred through the biogeophysical pathway. Interpretation LULCCs in southeast Asia are degrading air quality, causing thousands of excess deaths and billions of dollars in economic losses, with forest degradation and deforestation being the primary driver. The findings emphasise the need for strategic land management to improve environmental conditions and public health, and support sustainable economic development in the area, particularly in the countries most affected, such as Indonesia, Viet Nam, and Thailand. Funding Ministry of Education Singapore and Tsao Family Foundation.