Acute exposure to sulfur dioxide and mortality: Historical data from Yokkaichi, Japan.

We examined the association between acute exposure to sulfur dioxide (SO2) and mortality, using historical data from 1972-1991 in Yokkaichi, Japan. We used a time-stratified case-crossover study design. We included all causes of death, excluding external causes, between 1972 and 1991 in Yokkaichi and the neighboring town, Kusu of the Mie Prefecture (N = 29,839). We obtained daily estimations of SO2 concentrations during the study period. We then conducted conditional logistic regression analysis to examine association between SO2 exposure and all-cause and cause-specific mortality. Exposure to SO2 increased the risk of all-cause and cause-specific mortality in a non-linear manner. The relationship between SO2 exposure and mortality outcomes remained after adjustment for co-pollutants such as particulate matter and nitrogen dioxide. Historical data from Yokkaichi, Japan, showed that SO2 exposure increased the risk of all-cause and cause-specific mortality.