Air pollution and daily mortality in Cracow.

Several studies indicated that short-term increases in concentration of pollution in the atmosphere of a town may result in increased mortality in the days following the episode. To evaluate this relationship we analyzed data on daily mortality in Cracow, Poland, in the period 1977-1989 and data on daily concentrations of suspended particulates (PM 20) and sulfur dioxide (SO2) in the town area. This analysis was restricted to winter months. In 1167 winter days, an average of 18.4 deaths of Cracow residents occurred daily. PM 20 concentration exceeded 300 micrograms/m3 in 21%, and SO2 exceeded 200 micrograms/m3 in 19% of those days. The correlation coefficient of the daily number of deaths with the air pollution in the 24 hours preceding the day of death was 0.093 (p < 0.01) for PM 20, and was 0.141 (p < 0.001) for SO2. Similar correlations were found for air pollution levels in the four days preceding death, and the correlation decreased for earlier days. The effects were more pronounced in people over 65 years of age than in those younger, especially in males. After adjustment for SO2 levels, PM 20 had no additional effect on mortality. It was estimated that with an increase of SO2 concentration of 100 micrograms/m3, the daily number of deaths due to respiratory system diseases increased by 19% and deaths due to circulatory system diseases by 10%.