Daily mortality in Santiago and its relationship with air pollution

Background: Santiago de Chile, due to meteorological and topographic factors, is one of the most polluted cities in the world. The adverse effects of contamination on health are relatively well known, but they may be overvalued. Aim: To evaluate the short term effects of exposure to air pollution on mortality of people over 65 years old. Material and methods: Daily mortality data in Santiago, from 1988 to 1993, was obtained from the National Statistics Institute. Daily concentrations of contaminants in Santiago and meteorological variables, were obtained from SESMA the Metropolitan Environmental Health Services. An association between contamination and mortality due to respiratory or cardiovascular diseases in subjects over 65 years old was searched, using temporal series analysis. Results: There was a significant association between air pollution, meteorological values on the same and previous days and mortality. PM10 had the strongest association with mortality. The relative risk of a 100 mu g/m(3) increment in PM10 was 1.052 for the elderly, 1.025 for cardiovascular and 1.061 for respiratory mortality. The relative risk of SO2 was 1.006 for all deaths and 1.017 for respiratory deaths. The figures for O-3 were 1.015 for all deaths and 1.008 for cardiovascular deaths. Conclusions: This work confirms a consistent association between air pollution and daily mortality, specially for particulate matter, even for levels below Chilean norms.