*2.2. Data Source*

The time-average map of NO2 for consecutive 10- and 60-day average tropospheric columns (molecules/cm2) and time series daily area-average of NO2 tropospheric columns (30% cloud screened) with spatial resolution 0.25 × 0.25◦ from 24 November 2019 to 22 March 2020 were collected from Giovanni interface [63–65], Global Modeling and Assimilation Office, NASA. The hourly and daily average concentrations of CO, O3, NO2, PM10, PM2.5, SO2, and AQI data for 50 consecutive days before and 50 days after lockdown were collected from ground monitoring stations provided by the Ministry of Environmental Protection of China (MEPC), China Ministry of Ecology and Environment (https://aqicn. org/map/china/cn/, accessed on 20 March 2020) for the same study period.
