Factors influencing PM10 and PM2.5 concentrations before and during COVID-19 in subway stations of Seoul Metro

This study analyzed the trends in change and influencing factors based on particulate matter data from subway stations in 2019 and 2021 (before and during COVID-19). The measurements were based on subway stations on the Seoul Metro from lines 1 to 9. To confirm the changes in particulate matter concentrations before and after COVID-19, the trends of PM10 and PM2.5 concentrations in subway stations in 2019 and 2021 were analyzed. A correlation analysis was subsequently performed for a comparison of the factors influencing changes in the particulate matter concentrations. Overall, both PM10 and PM2.5 concentrations decreased during the outbreak compared to before the COVID-19 outbreak, with rates of 20.7% and 22.8%, respectively. In conclusion, the PM10 and PM2.5 concentrations in the Seoul Metro subway stations during COVID-19 were reduced. The reduction in PM10 and PM2.5, during the COVID-19 period, was the result of government policies such as telecommuting recommendations, subway congestion forecasting systems, and increased ventilation.