Spatiotemporal heterogeneity analysis of air quality in the Yangtze River Delta, China

•The annual averages of the AQI in the Yangtze River Delta (YRD) region from 2016 to 2018 are 78.6, 74.2, and 69.7, respectively, exhibiting a pattern of year-to-year decrease.•Among the 41 metropolitan areas of the YRD, the correlation coefficients of PM2.5 across metropolitan areas are between 0.75 and 0.95. PM2.5 is the primary pollutant in 36 metropolitan areas, accounting for 88% of the pollution in the studied areas.•The study results demonstrate that the six impact factors have positive or negative correlations with AQI with significant spatial differences. The mean values of the regression coefficients indicate that relative humidity has the greatest effect on AQI values, followed by rainfall, temperature, wind speed, air pressure, and normalized difference vegetation index (NDVI); of which relative humidity has a positive correlation with AQI while air pressure has negative correction with AQI in the whole study area.