Effects of COVID-19 on PM air quality in South Korea

In winter and early spring (December to March), haze events frequently have occurred with high particulate matter (PM) concentrations in the Korean Peninsula. In particular, the northwest wind facilitates long-range transport of PM and its precursors from China, and stagnation associated with high pressure systems provides a favorable condition for accumulating PM in the Korean Peninsula and broadly East Asia. COVID-19, which unexpectedly occurred last winter, however, has caused significant declines of social activities throughout East Asia, which may have directly affected PM air quality. In this study, we investigate the impact of COVID-19 on PM air quality in South Korea using a global 3-D chemical transport model (GEOS-Chem). We use the KORUS v5 inventory for anthropogenic emissions in East Asia and consider optimal East Asian emissions in 2020 based on PM_2.5 and its precursor observations in surface air. We find that the PM air quality in South Korea last winter was greatly improved due to COVID-19 as well as favorable meteorological conditions. Reduction policies in South Korea also contributed to low PM_2.5 concentrations. In this presentation, we quantify individual contributions of COVID-19, emission reduction policies, and meteorological conditions to changes in PM_2.5 concentrations in South Korea last winter.

<Acknowledgement>

This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Public Technology Program based on Environmental Policy Program, funded by Korea Ministry of Environment(MOE) (2019000160002).