Analysis of the Factor Affecting in the recent Air Quality changes in South Korea and China in winter

 The factors affecting the change in air quality must be objectively analyzed, and this study used chemical transport model and observational data to investigate the contributions of each factor. The data analysis focuses on air quality changes in China and South Korea from 2016 to 2020, and existing emission data were adjusted based on observational data to reflect the trend of emission reduction into chemical transport model. The observational data revealed that in China and South Korea, respectively, the PM2.5 concentration in winter in 2020 reduced by -23.7% (-11.58 µg/m³) and -19.2% (-4.97 µg/m³) compared to 2016. Meteorological condition, emission control policy, and unexpected events are major factors which may affect the change in air quality, and each of these factors has a different effect on the concentration of PM_2.5. The impact of meteorological conditions in China and South Korea in 2020, resulted in increases in PM_2.5 concentration of +7.6% and +9.7%, respectively, compared to 2016. However, due to the long-term emission control polices implemented in both countries, PM_2.5 concentration decreased in China (-26%) and South Korea (-5%). In addition, the newly imposed policy during the study period (winter) and the unexpected coronavirus outbreak had an impact on the PM_2.5 concentration in 2020. It was discovered to have decreased by -5% and -19.5%, respectively, in China and South Korea, which was not a negligible amount. Considering the impact of each quantified factors can provide a reliable scientific foundation for upcoming policymaking or air quality assessments.

This work was supported by Korea Environment Industry &Technology Institute(KEITI) through "Climate Change R&D Project for New Climate Regime." , funded by Korea Ministry of Environment(MOE) [Grant Number : 1485018907].