Fig. 4From: Do green spaces affect the spatiotemporal changes of PM2.5 in Nanjing?Spatial changes in the mean and variation (standard error (SE)) of PM2.5 concentration over four seasons during the study period from July 2013 to May 2015. The inverse distance weighted (IDW) method was used in the spatial interpolations with the exponential distance of 12 and 9 as the number of pointsBack to article page