Asia is of global importance economically, yet data on ambient persistent organic pollutant levels are still sparse for the region, despite international efforts under the Stockholm Convention to identify and reduce emissions. A large-scale passive air sampling survey was therefore conducted in Asia, specifically in China, Japan, South Korea, and Singapore. Polyurethane foam disks were deployed simultaneously at 77 sites, between Sept 21 and Nov 16, 2004, and analyzed for polychlorinated biphenyls (PCBs), organochlorine compounds (hexachlorobenzene (HCB), dichlorodiphenyltrichloroethanes (DDTs), chlordane), and polybrominated diphenyl ethers (PBDEs). The meteorological conditions prevailing in the region at this time facilitated the assessment of local/regional differences in atmospheric emissions, because large-scale advection effects due to monsoons or dust storms did not occur. Air concentrations estimated assuming an average sampler uptake rate of 3.5 m3/day ranged as follows (pg m(-3)): PCBs, 5-340; HCB, 10-460; DDTs, 0.4-1800; chlordanes, 1-660; PBDEs, < 0.13-340. South Korea and Singapore generally had regionally low concentrations. Elevated concentrations of PCBs, DDTs, and HCB occurred at sites in China, higher than reported in a similar recent sampling campaign in Europe. Chlordane was highest in samples from Japan (which also had elevated levels of PCBs and DDTs) and was also elevated in some Chinese locations. PBDE levels were generally low in the region.

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The levels and distribution of polynuclear aromatic hydrocarbons (PAHs) were investigated in global background soil samples. Total PAH concentrations (sum of 15 compounds) ranged over 5 orders of magnitude, from <1 to 7,840 (mean 328) ng g(-1) dry weight. The order was generally Europe > North America > Asia > Oceania > Africa > South America. Proximity to long-term emissions sources and locations susceptible to high atmospheric depositional inputs tended to have higher concentrations. A broad positive correlation was obtained between population density and soil PAH concentrations (i.e. source-related factors). However, concentrations were also influenced by the holding capacity of the soils (i.e. sink-related factors) with statistically significant correlations observed between PAHs and soil organic matter (SOM), and black carbon (BC).