Atmospheric corrosion effects of air pollution on materials and cultural property in Kathmandu, Nepal

Carbon steel, zinc and limestone samples were exposed in Kathmandu for one year. Their corrosion was measured at ten locations and related to SO2, NO2, O-3, HNO3 and PM concentrations and climatic factors. Corrosion rates vary considerably and are correlated mainly with the SO2 concentration. Estimated policy targets for SO2 are most stringent for limestone, in the range 3 to 6gm(-3). The Kathmandu carbon steel and limestone samples matched a general pattern from exposures at more than twenty sites in Asia and Africa. At these Asian/African sites corrosion of copper is generally higher than corrosion of zinc. This is in contrast to experiences from European conditions where corrosion of zinc is higher than corrosion of copper.