Long-term evolution and synoptic meteorological modulation of PM2.5 and PM10 in Seoul

Abstract

Addressing particulate matter (PM) pollution in megacities like Seoul is crucial for public health and environmental sustainability, necessitating a comprehensive understanding of its long-term evolution and meteorological drivers. This study investigated the key factors affecting long-term PM concentrations in Seoul, South Korea, from 2000 to 2021, with a focus on the winter (DJF) and spring (MAM) seasons. To address the gap in PM research caused by the shorter observation period of PM_2.5 compared with PM₁₀, we used an extended PM_2.5 dataset. This enabled a detailed analysis of PM_2.5 and its relationship with PM₁₀, which, despite some differences, generally displayed similar variability. Both PM_2.5 and PM₁₀ exhibited decreasing trends in winter as well as spring, although the rate of decline slowed in the last decade (2011–2020) compared with the earlier decade (2000–2010). Both seasons exhibited a strengthened interannual correlation between PM_2.5 and PM₁₀ in the last decade. Daily PM_2.5 and PM₁₀ levels generally fluctuated in a similar pattern in both seasons, which can be attributed to synoptic-scale meteorological systems, particularly migratory systems from Northwest China, which can remain stationary over Korea for several days, particularly in winter. This pattern continues into spring, albeit with a lower intensity. These findings provide valuable insights into PM_2.5 variability and its correlation with PM₁₀ over time, which may inform future PM_2.5 mitigation strategies.