Time series analysis of air pollution and mortality: effects by cause, ageand socioeconomic status

Objective-To investigate the association between outdoor air pollution and mortality in Sao Paulo, Brazil. Design-Time series study Methods-All causes, respiratory and cardiovascular mortality were analysed and the role of age and socioeconomic status in modifying associations betw een mortality and air pollution were investigated. Models used Poisson regr ession and included terms for temporal patterns, meteorology, and autocorre lation. Main results-All causes all ages mortality showed much smaller associations with air pollution than mortality for specific causes and age groups. In t he elderly, a 3-4% increase in daily deaths for all causes and for cardiova scular diseases was associated with an increase in fine particulate matter and in sulphur dioxide from the 10th to the 90th percentile. For respirator y deaths the increase in mortality was higher (6%). Cardiovascular deaths w ere additionally associated with levels of carbon monoxide (4% increase in daily deaths). The associations between air pollutants and mortality in chi ldren under 5 years of age were not statistically significant. There was a significant trend of increasing risk of death according to age with effects most evident for subjects over 65 years old. The effect of air pollution w as also larger in areas of higher socioeconomic level. Conclusions-These results show further evidence of an association between a ir pollution and mortality but of smaller magnitude than found in other sim ilar studies. In addition, it seems that older age groups are at a higher r isk of mortality associated with air pollution. Such complexity should be t aken into account in health risk assessment based on time series studies.