Ozone short-term exposure and acute coronary events: a multicities study in Tuscany (Italy)

OBJECTIVE

Many studies have investigated the potential role of ozone exposure in cardiovascular mortality and morbidity. The effects on specific cardiovascular outcome and the role of individual susceptibility are less studied. This paper focuses on the short-term effects of ozone on acute coronary events and it investigates comorbidities as indicators of personal susceptibility.

SETTING AND PATIENTS

This study was conducted in five urban areas of the Tuscany region (Italy) covering the period January 2002-December 2005. Air quality and meteorological data from urban background monitoring sites were collected. Hospital admissions for acute myocardial infarction and out-of-hospital coronary deaths were extracted from administrative database.

DESIGN

Both time series and case-crossover designs were applied. The confounding effects of some time-dependent variables, such as temperature, were taken into account. Some potential susceptibility factors were investigated. Pooled estimates were derived from random-effect meta-analysis.

RESULTS

During the warm season 4555 hospitalized acute myocardial infarctions and 1931 out-of-hospital coronary deaths occurred. Authors estimated a 6.3% (95% confidence interval, 1.2%, 11.7%) increase in out-of-hospital coronary deaths for a 10 μg/m3 increase in ozone (lag 0-5). Results also suggested higher risks for females, elderly, and patients previously hospitalized for cerebrovascular and artery diseases.

CONCLUSIONS

This study adds further evidence to the relation between cardiovascular diseases and ozone exposure, showing an adverse effect on out-of-hospital coronary deaths, but not on hospitalized acute myocardial infarctions. Some susceptible subgroups, such as females, elderly, and patients affected by some chronic diseases, are likely to be at major risk.