Fig. 3: Diurnal variations of air pollution in the warm season.

Six columns represent diurnal variations of PM2.5, PM10, O3, NO2, CO, and SO2, respectively. BJT means Beijing Time, and BJT = UTC + 8 h.

Six columns represent diurnal variations of PM2.5, PM10, O3, NO2, CO, and SO2, respectively. BJT means Beijing Time, and BJT = UTC + 8 h.