The NASA Pacific Exploratory Mission-West A (PEM-West A) experiment in 1991 covered large portions of the northwestern Pacific Ocean troposphere and a transect of the subtropical troposphere of the North Pacific Ocean. Sulfur dioxide consistently increased with altitude from the surface to 11 km except for a few cases of anthropogenic inputs confined to the planetary boundary layer. Using the PEM West A data set for SO2, sulfate, and calculated OH over the central Pacific Ocean, we have estimated the impacts of the SO2 on the formation of condensation nuclei and the lifetimes of SO2 and sulfate for this region. ¿ American Geophysical Union 1996