“…Recent studies have suggested that airborne pollutants, PM 2.5 in particular, are closely related to cardiovascular disease-related mortality (Garrett and Casimiro, 2011;Li et al, 2015a;Lanzinger et al, 2015), emergency room visits and all-year non-accidental mortality (Pasca et al, 2014). Due to its strong negative influences on public health, scholars have been working towards a better understanding of sources (Guo et al, 2012;Zhang et al, 2013Zhang et al, , 2016Gu et al, 2014;Cao et al, 2014), characteristics (Wei et al, 2012;Zhang et al, 2013;Hu et al, 2015;F. Zhang et al, 2015;Zhen et al, 2016) and seasonal variations (Cao et al, 2012;Shen et al, 2014;Yang and Christakos, 2015;Chen et al, 2015; of PM 2.5 .…”