COVID-19PM 2.5 1 * 2,3 2 2 Drastic Changes of PM 2.5 Trans-Boundary Pollution over Japan Due to COVID-19 Lockdown in China

In order to prevent the spread of COVID-19, the Chinese government imposed a lockdown During this period, anthropogenic emissions will be reduced;therefore, the trans-boundary air pollution will be changed The analysis of surface observations by the automated aerosol chemical speciation analyzer (ACSA) showed that the dramatic reduction with 3050 of PM 2 5 , sulfate (SO 4 2), and nitrate (NO 3) on FebruaryMarch 2020 compared to 20182019 The results of the chemical transport model suggested that the reduction of SO 4 2 was mostly caused by SO 2 emission reduction whereas that of NO 3 was dominated by the meteorological variability The record high warm winter on 2020 was related to the unfavorable condition to produce NO 3