Background air levels of polychlorinated biphenyls in China.

Measurements of the atmospheric concentrations of polychlorinated biphenyls (PCBs) were taken in 11 background sites geographically distributed throughout China. Active high-volume samplers were employed during two deployment periods between November 2007 and November 2008. 12 dioxin-like and 7 indicator PCBs were identified and measured. To keep the consistency, the two sampling periods were set in the same seasons (autumn and winter) and there were few variations between the results at all sites. The congener profile of indicator PCBs was dominated by CB28 and CB52. The most abundant mono-ortho congener was CB118, and the most abundant non-ortho congener was CB77. This study is the first systematic investigation into background atmospheric PCB levels in China. The background indicator ∑(7)PCB levels in China are similar to those obtained at other background areas around the world.