Revised Temporal Trends of Persistent Organic Pollutant Concentrations in Air around the Great Lakes

The concentrations of polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAH), and several chlorinated insecticides in air have been measured every 12 days since 1991 at several sites on the shores of the North American Great Lakes. We give here the geometric mean concentrations for each of these compounds for each year and at each site. In most cases, these concentrations have been measured in both the vapor and particle phases; if concentrations were available for both phases, the two concentrations were summed, and those data are presented here. Assuming a first-order rate model for these data, we have calculated the time it takes for the concentrations to decrease by half. For most compounds, the halving times are the same for the vapor phase and for the vapor and particle phase concentrations summed together. The halving times are generally not distinguishable among the sites. Overall, the observed halving times are 8–15 years, except for that of lindane, which is disappearing with a halving time of ∼4 years.