Chloride Accumulation on Indoor Zinc and Aluminum Surfaces

Abstract

The long-term accumulation f chloride and other ions on indoor zinc and aluminum surfaces in 15 U.S. cities has been measured. For most ionic contaminants, he accumulation zinc and aluminum surfaces is similar, suggesting that partic-ulate deposition isthe most likely mode of accumulation. Chloride accumulation aluminum occurs by particulate depo-sition, but on zinc surfaces, attack by reactive chlorine containing gases also contributes toaccumulation. I New York City and Philadelphia, chloride accumulation is very rapid on all zinc surfaces but not on aluminum surfaces. Volatilization of chloride, probably as HC1 or NH4C1, seems to contribute to the low chloride concentrations observed on aluminum surfaces in these cities. In Wichita and Houston, deposition of coarse chloride containing particulates produces rapid accumulation of chloride on horizontal zinc and aluminum surfaces while chloride accumulation on vertical surfaces is low. As part of a broad study to determine the amounts and effects of major inorganic pollutants in indoor environments (1, 2), the long-term accumulation of chloride on indoor zinc and a luminum surfaces at tele-phone company switching centers in 15 U.S. cities has been measured (3). In the previous reports (1, 2) on