Levels and isomer profiles of dechlorane plus in Chinese air.

The highly chlorinated flame retardant, Dechlorane Plus (DP), was measured in air across 97 Chinese urban and rural sites. DP was detected in 51 of these sites, with a mean air concentration in urban centers (15.6 +/- 15.1 pg m(-3)) approximately 5 times greater than those measured in rural areas (3.5 +/- 5.6 pg m(-3)). These DP levels were likely attributable to local sources rather than trans-boundary influences. Elevated urban levels were measured along the southeastern coast and in south-central China; the highest concentration was observed in the city of Kunming (66 pg m(-3)). Few of the urban samples (7%) and a majority of the rural samples (62%) were below the method detection limit, notably areas in rural central and northeastern China. The mean fractional abundance of the syn-DP isomer (f(syn)) in all samples was 0.33 +/- 0.10, values indistinguishable from that of a commercial mixture (f(syn) = 0.35). This paper represents the first report on DP levels in Chinese air, together with isomeric ratio profiles from urban and rural sites.