Current Research on Aerosols at Pacific Northwest Laboratory1

Construction of a new bridge span over San Francisco Bay in the summer of 1967 made feasible for the first time continuous measurement of oxidant levels at a mid-bay site. Hypotheses of higher or lower oxidant levels over a central body of water in an urban complex could thus be evaluated. No significant bay effect, positive or negative, was found in the mean data, but analysis on a case basis showed that conditions favoring adverse oxidant development over the region favored even higher levels over the bay itself. Patterns of oxidant concentration reinforced by the mid-bay data show a broadly distributed community air pollution level, and they support the mixing of oxidant precursors from area-wide sources so that the bay and the surrounding land are equally involved as sites for the photochemical process of oxidant formation.