Fig. 6.
Time-varying percentage changes of PM2.5 concentrations for 34 sites from FEB to JUN relative to Pre-LD based on scaling factors from GAM analysis. (a): The sites outside of Fifth Ring Road. (b): The sites within Fifth Ring Road. The subplot within the black rectangle represents mean lockdown effects of the sites within Fifth Ring Road. The blue bars represent mean percentage changes in PM2.5 concentrations. The upper and lower error bars represent the uncertainty of lockdown effects obtained from 100 bootstrap runs. All bars have the same scales. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)