Fig. 5. Observed and deweathered daily PM_2.5 concentrations in the selected cities before and after the lockdown start dates or equivalent in 2020 versus 2018.

Columns correspond to (A) roadside, (B) urban background, and (C) rural sites; rows show different cities as indicated. Fine and heavy lines indicate observed and deweathered concentrations, respectively. Data are shown from December to May, shown as day of year (1 January = 1), where the vertical dashed lines represent lockdown start date. Results from other cities/sites are shown in fig. S2. No data are available for roadside sites in Wuhan.