Scant Evidence for Long-Range Atmospheric Transport of Particle-Bound Benzotriazole Ultraviolet Stabilizers.

Despite benzotriazole UV stabilizers (BT-UVs) being widely used since the 1960s, few empirical data on their atmospheric presence exist. UV-328 was added to the Stockholm Convention on Persistent Organic Pollutants, based in part on model calculations indicating atmospheric long-range transport potential. We investigated the atmospheric occurrence of BT-UVs at multiple sites that differ greatly in their proximity to potential sources. UV-P, UV-328, UV-234, UV-326, UV-329, and UV-327 were quantified in active air samples collected in suburban Toronto, on Saturna Island in the Salish Sea, at Point Petre on Lake Ontario, and in Alert, Nunavut, as well as in XAD-resin based passive air samplers deployed at sites in British Columbia and Quebec. As the most volatile BT-UV, UV-P was present in the gas phase across all sampling locations, with higher concentrations in urban areas. The five less volatile BT-UVs were present only in active air samples from suburban Toronto and were not found above detection limits (0.03-1.7 pg·m) anywhere else. Empirical evidence thus does not support model predictions of long-range atmospheric transport of particle-bound BT-UVs. Predictions based on simple model calculations should be supported by empirical data if they are to be used as the basis for regulatory decisions.