PM10 exposure, gaseous pollutants, and daily mortality in Inchon, South Korea

To evaluate the relative importance of various measures of particulate and gaseous air pollution as predictors of daily mortality in Inchon, South Kor ea, the association between total daily mortality and air pollution was inv estigated for a 20-month period (January 1995 through August 1996). Poisson regression was used to regress daily death counts on each air pollutant, c ontrolling for time trends, season, and meteorologic influences such as tem perature and relative humidity. Regression coefficients of a 5-day moving a verage of particulate matter less than or equal to 10 mu m in aerodynamic d iameter (PM10) on total mortality were positively significant when consider ed separately and simultaneously with other pollutants in the model. PM10 r emained significant when the models were confined to cardiovascular or resp iratory mortality. Sulfur dioxide (SO2) and carbon monoxide (CO) were signi ficantly related to respiratory mortality in the single-pollutant model. Oz one exposure was not statistically significant with regard to mortality in the above models, and graphic analysis showed that the relationship was non linear. A combined index of PM10, nitrogen dioxide, SO2, and CO seemed to b etter explain the exposure-response relationship with total mortality than an individual air pollutant. Pollutants should be considered together in th e risk assessment of air pollution, as opposed to measuring the risk of ind ividual pollutants.