The relationship between UP-POPs concentrations in the ambient air and stack gases
Although there were also large variation in the UP-POPs concentrations in the stack gases emitted from different plants. we found that there were clear correlations between the ambient air and the stack gas concentrations of the PCDD/Fs, dl-PCBs and PCNs among the five investigated plants, respectively (Fig. 1). For instance, if relatively high UP-POPs con- centrations were found in the stack gas emitted from an investi- gated plant, the corresponding levels in its ambient air were also found to be higher than those of other plants. When the UP-POPs concentrations in the stack gases emitted from an investigated plant were relatively low, the corresponding levels in its the ambient air were also lower than those of other plants. The result indicated that the secondary copper and aluminum smelters investigated may be a major UP-POPs source in their ambient air