Recent increase of surface particulate matter concentrations in the Seoul Metropolitan Area, Korea

TLDR

Recent changes in surface particulate matter concentrations in the Seoul Metropolitan Area are puzzling. The study investigates the relationship between interannual variations of surface PM concentration and wind speed in South Korea. The authors conducted a 12‑year regional air‑quality simulation at 27‑km over East Asia and 9‑km over South Korea to isolate meteorological effects while keeping anthropogenic emissions constant. Long‑term PM levels declined in the 2000s but have risen since 2012, coinciding with severe hazes, and simulations reveal a strong negative correlation (R = −0.86) between PM and regional wind speed, indicating that reduced ventilation leads to stagnant conditions and higher pollution, yet when meteorology‑driven variability is removed, PM concentrations have continued to decline, underscoring the effectiveness of emission controls.

Abstract

Abstract Recent changes of surface particulate matter (PM) concentration in the Seoul Metropolitan Area (SMA), South Korea, are puzzling. The long-term trend of surface PM concentration in the SMA declined in the 2000s, but since 2012 its concentrations have tended to incline, which is coincident with frequent severe hazes in South Korea. This increase puts the Korean government’s emission reduction efforts in jeopardy. This study reports that interannual variation of surface PM concentration in South Korea is closely linked with the interannual variations of wind speed. A 12-year (2004–2015) regional air quality simulation was conducted over East Asia (27-km) and over South Korea (9-km) to assess the impact of meteorology under constant anthropogenic emissions. Simulated PM concentrations show a strong negative correlation (i.e. R = −0.86) with regional wind speed, implying that reduced regional ventilation is likely associated with more stagnant conditions that cause severe pollutant episodes in South Korea. We conclude that the current PM concentration trend in South Korea is a combination of long-term decline by emission control efforts and short-term fluctuation of regional wind speed interannual variability. When the meteorology-driven variations are removed, PM concentrations in South Korea have declined continuously even after 2012.