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 PM2.5 compared with PM10, we used an extended PM2.5 dataset. This enabled a detailed analysis of PM2.5 and its relationship with PM10, which, despite some differences, generally displayed similar variability. Both PM2.5 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 PM2.5 and PM10 in the last decade. Daily PM2.5 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 PM2.5 variability and its correlation with PM10 over time, which may inform future PM2.5 mitigation strategies.