Sulphur dioxide exposure and lung function in a Norwegian and Russian population living close to a nickel smelter

The Norwegian-Russian border area is polluted by sulphur dioxide (SO2) emitted from a Russian nickel smelter in the city of Nikel. We studied the effects of daily variations in SO2 on the lung function levels of people on both sides of the border. A cross-sectional population-based study was performed among adults in Sør-Varanger, Norway (n = 3438) and Nikel, Russia (n = 1613). All subjects were assigned 24 h mean SO2 concentrations for their day of screening and the day before on basis of residency. The SO2-concentrations were compared with the daily recordings of forced expiratory volume in one second expressed as percentage of the predicted value (FEV1% predicted). In Sør-Varanger, no significant associations between SO2 and FEV1% predicted were found. In Nikel, FEV1% predicted was exceeded non-systematically in some of the exposure categories (10-50, 50-90, or > 90 micrograms/m3) compared to the reference exposure group (0-10 micrograms/m3). In conclusion, neither of the study populations suffered from a measurable reduction in lung function when SO2 increased above the reference level.