Persistent organic pollutants in air across the globe using a comparative passive air sampling method

For the global monitoring plan (GMP) established under the Stockholm Convention on Persistent Organic Pollutants (POPs), passive air samplers (PAS) equipped with polyurethane foam disks (PUFs) were recommended for generating comparative results on the presence of POPs in countries. One representative sampling location was designed in each of the 42 countries and the PAS/PUFs exposed for three months to collect POPs during 2017-2019. The PUFs were analyzed in three laboratories according to their chemical nature and concentrations reported per PUF and 90 +/- 3 days of exposure. In total, 381 PUFs were analyzed for organochlorine pesticides (OCPs), industrial chlorinated POPs, dioxin-like POPs (dl-POPs), brominated flame retardants (BFRs), and perfluoroalkane substances (PFAS). Concentrations typically varied by a factor of up to three for a POP and often within the same geographic region or other denominator such as similar latitudes or altitudes. Maximum values were found for DDT (895 ng/PUF) in Africa, but the highest medium value was in the Latin American countries. Also, polychlorinated biphenyls (PCB) and hexachlorobenzene (HCB) were most abundant across all parameters assessed. Noteworthy were high values in single countries, such as DDT in the Solomon Islands, toxaphene in Mexico, beta-HCH and lindane in Tanzania, hexachlorobutadiene and hexabromocyclododecone in Mongolia, deca-BDE and PFOS in Zambia. Although we had two sampling locations at very high altitudes, >2000 m, we could determine increasing POPs concentrations with increasing altitudes only for HCB but not for other POPs. A general dependency on latitudes with higher concentrations towards the north and south pole could not be found, although the most northern station in Mongolia had two of the maxima and elevated values for some legacy POPs.