Fig. 2From: Spatiotemporal characterization of aerosols and trace gases over the Yangtze River Delta region, China: impact of trans-boundary pollution and meteorologyThe inter-annual variation of a NO2, b O3, c SO2, d PM2.5, e PM10 and f PM2.5/PM10 in Hangzhou, Nanjing, Hefei and Shanghai during 2018–2021Back to article page