Objective: To estimate the short-term association between levels of air pollution due to suspended particulates and several indicators of morbidity and mortality in the city of Valencia, Spain.
Methods: We performed an ecological time-series study. Daily levels of air pollution from black smoke were related to indicators of mortality, hospital admissions, and visits to emergency departments in the city of Valencia between 1994 and 1996. The magnitude of the association was estimated through Poisson autoregression using generalized additive models. The form of the relationship, the delayed effect of pollution, and the possible modification of this effect by other pollutants or periods of the year were assessed.
Results: A significant association was found between levels of suspended particulates and several of the indicators analyzed in Valencia. The form of this relationship was linear. An increment of 10 microg/m3 in the daily levels of black smoke was associated with an increase of 1.8% (95% confidence interval: 0.9-2.7%) in the number of deaths on the following day. The same increment in pollutant levels was associated with an increase of 1.5% (0.1-2.8%) in deaths from all cardiovascular causes, an increase of 1.3% (0.0-2.6%) in admissions for all cardiovascular diseases and in an increase of 5.4% (0.6-10.4%) in the number of emergency visits for asthma. This association was not confounded by levels of other pollutants. Black smoke was not associated with mortality from respiratory diseases, with hospital admissions for cerebrovascular diseases, or with emergency visits for chronic obstructive pulmonary disease.
Conclusions: This study provides evidence that levels of suspended particles in Valencia are associated with emergency visits for asthma, hospital admissions for cardiovascular diseases, and daily deaths. The association found is consistent with the results of previous studies and fits with recent knowledge of psychopathological mechanisms.