Spatial concentration, congener profiles and inhalation risk assessment of PCDD/Fs and PCBs in the atmosphere of Tianjin, China

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were monitored in a seasonal passive sampling scheme during June 2008 and January 2009 to investigate the spatial concentration, congener profiles and evaluate the potential inhalation risk in different functional areas in Tianjin, China. The spatial air concentrations and I-TEQs ranged 1.08x10(2)-8.19x10(3) fg m(-3) (average 2.63x10(3) fg m(-3)) and 4.08-325 fg I-TEQ m(-3) (average 91.4 fg I-TEQ m(-3)) respectively for PCDD/Fs. The concentration and I-TEQs of PCBs were 3.08x10(4)-3.01x10(5) fg m(-3) (average 1.39x10(5) fg m(-3)) and 1.72-49.6 fg I-TEQ m(-3) (average 18.5 fg I-TEQ m(-3)). It is obvious that PCB concentrations were several hundred times higher than the PCDD/Fs. However, the ambient air PCDD/Fs contributed a major part to the total toxicity equivalents, varying from 72.7% to 89.0% (average 81.8%). The atmospheric PCDD/F levels were observed to be higher in winter for most of sampling sites in the downtown. Besides, inhalation risk assessment showed that local residents might suffer more risk near the point sources than those in living area, industrial zones and background area in Tianjin City. However, the total daily dioxin intake was approximately several to hundreds of times lower than the WHO criteria, showing relatively low exposure risks from the impact of industry point sources in Tianjin City.