Air Pollution and Health Impacts in Southeast Asia under Present and Future Climate

Southeast Asia faces escalating air quality challenges driven by rapid development, climate change, and transboundary pollution, with significant implications for human health. This talk will summarize the recent regional modelling studies in NTU Centre for Climate Change for Environmental Health (CCEH) that quantifies present-day and future health impacts of surface ozone (O₃) and fine particulate matter (PM_2.5) across Southeast Asia under different emission and climate pathways. Using state-of-the-art chemical transport and climate–air quality models, we assess pollutant formation regimes, source contributions, and premature mortality under current conditions and future Shared Socioeconomic Pathways (SSPs).

We find that urban O₃ in major Southeast Asian cities is sensitive to both nitrogen oxides (NOₓ) and volatile organic compounds (VOCs), requiring synergistic precursor controls, while suburban, rural, and maritime regions remain predominantly NOₓ-limited. Under sustainable emission pathways, O₃-attributable premature mortality is projected to decline substantially by mid-century, whereas high-emission scenarios lead to marked increases. For PM_2.5, Southeast Asia is largely ammonia-rich, limiting the effectiveness of NH₃ controls, while reductions in VOCs and sulfur dioxide are more effective in lowering secondary PM_2.5. Although climate change is projected to slightly reduce regional PM_2.5 concentration, PM_2.5-attributable premature mortality is expected to increase due to demographic changes, resulting in substantial economic losses. We further show that haze pollution is shaped by both local emissions and transboundary transport, strongly modulated by climate variability such as El Niño and the Indian Ocean Dipole. Overall, integrated air quality and climate policies are essential to mitigate future health burdens in Southeast Asia.