Most of the field data that have been gathered on atmospheric corrosion of metals over the years were obtained from standardized test specimens, for example 10x15 cm coupons mounted at 0 degrees to the horizontal facing south. This practice can provide useful data on the relative corrosion resistance of alternative alloys and coatings, but is not particularly useful with regard to deducing the various mechanisms responsible for these corrosion differences. Mechanistic experiments have traditionally been performed under controlled conditions in test chambers, but such controlled conditions are not necessarily representative of the complex mixtures of pollutants and meteorological conditions that occur in real atmospheres. The data analyzed in this paper were intended to provide mechanistic data for galvanized steel under semi-controlled field conditions at Research Triangle Park, NC, a site that would be considered clean in the context of much of the corrosion data in the literature. These experiments were intended to provide data that would allow surface chemistry and atmospheric processes to be considered separately.