[SO2 air pollution and hospital admissions in Ravenna: a case-control study]

The association between air pollution and hospital admission for chronic respiratory and ischemic heart diseases was analyzed through a case-control approach. The study was based on routinely available data in Ravenna and covered the period 1986-88. A control group (n = 37250) was used to evaluate the specificity of the health effects of air pollution. It included all patients admitted into the hospital for conditions other than respiratory or heart diseases. The adjustment for confounding variables (climatic factors and time variables) was attained by multiple logistic regression. The risk of hospital admission for chronic bronchitis (n = 587) increased of 10% for a 10 ppb increase in SO2 concentration (in the range 0-60 ppb). A similar positive association (OR = 1.2) was observed for exposures to more than 10 ppb of SO2 and hospitalization for ischemic heart diseases (n = 1982). An apparently inverse relationship was found between SO2 pollution and hospitalization for asthma (n = 203). The case-control method can be a useful alternative tool to elucidate specific associations, in comparison with the statistical methods most frequently used in time-correlation analysis.