Air pollution and emergency hospital admissions for cardiovascular diseases in Valencia, Spain

Variation saisonnière des accidents vasculaires cérébraux et influence des conditions météorologiques

The aim of this paper was to study the seasonal and Monthly distribution of different subtypes of strokes, and also the influence of the most usual meteorological factors on their incidence. The study, based on the population-based data of the Dijon register of stroke (France), involved 3287 patients with a cerebrovascular event during the Years 1985-1998. The seasonal distribution pointed out a summer decrease for all stroke subtypes. The cerebrovascular risk was the highest in autumn for small artery atheroma infarcts and for cerebral infarcts and, among these later, for cardioembolic infarcts and large artery atheroma infarcts, as well as for subarachnoid hemorrhages and for the total number of strokes. It was followed by spring (total number of strokes, small artery atheroma infarcts, cerebral infarcts) and/or winter (subarachnoid hemorrhages, cerebral infarcts, cardioembolic infarcts and large artery atheroma infarcts). For intracerebral hemorrhages, the risk peaked in spring and secondly in autumn. But the difference from one season to another was significant only for total number of strokes, cerebral infarcts and, among the later, for cardioembolic infarcts and large artery atheroma infarcts. As regards the Monthly distribution, the difference between Months was significant only for the total number of strokes and cerebral infarcts, with a minimum from July to September and a maximum in October for the later. Correlations with meteorological data were found for the total number of strokes, cerebral infarcts, cardioembolic infarcts, large artery atheroma infarcts and small artery atheroma infarcts. They showed an influence of temperature and relative humidity of the day of stroke or of the one to five days before. Correlations with wind speed, duration of sunshine or snow, even if less frequent, could also be found. Such results sometimes differ from those of some earlier studies, for which the climate and the risk factors were not the same, showing that regional epidemiological studies are necessary in order to determine the relations between seasons, meteorological factors and strokes.

Temperature, air pollution, and hospitalization for cardiovascular diseases among elderly people in Denver

Daily measures of maximum temperature, particulate matter less than or equal to 10 micro m in aerodynamic diameter (PM10), and gaseous pollution (ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide) were collected in Denver, Colorado, in July and August between 1993 and 1997. We then compared these exposures with concurrent data on the number of daily hospital admissions for cardiovascular diseases in men and women > 65 years of age. Generalized linear models, assuming a Poisson error structure for the selected cardiovascular disease hospital admissions, were constructed to evaluate the associations with air pollution and temperature. After adjusting the admission data for yearly trends, day-of-week effects, ambient maximum temperature, and dew point temperature, we studied the associations of the pollutants in single-pollutant models with lag times of 0-4 days. The results suggest that O3 is associated with an increase in the risk of hospitalization for acute myocardial infarction, coronary atherosclerosis, and pulmonary heart disease. SO2 appears to be related to increased hospital stays for cardiac dysrhythmias, and CO is significantly associated with congestive heart failure. No association was found between particulate matter or NO2 and any of the health outcomes. Males tend to have higher numbers of hospital admissions than do females for all of the selected cardiovascular diseases, except for congestive heart failure. Higher temperatures appear to be an important factor in increasing the frequency of hospitalization for acute myocardial infarction and congestive heart failure, and are associated with a decrease in the frequency of visits for coronary atherosclerosis and pulmonary heart disease.

[Particulate air pollution and health in Valencia [Spain] 1994-1996]

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.