Low Air Pollution and Cardiovascular Mortality: a Population Based Case-Crossover Study

Abstract

Background: The aim was to study short-term associations of NO2, O3, PM10, SO2, and H2S concentrations and cardiovascular mortality in Reykjavik capital area. Methods: Data on daily mortality were obtained from the National Cause-of-Death Registry, Statistics Iceland, during 2003 to 2009. One hour measures of NO2, O3, PM10, SO2, and H2S were obtained from the Environment Agency of Iceland for the same time period. A time-stratified case-crossover design was used to estimate the possible effect of short-term exposure of air pollution and cardiovascular mortality. Results: The total number of deaths due to cardiovascular causes over the study period was 2,070 cases. The inter-quartile range (IQR) of the 24-hour concentration levels of NO2, O3, PM10, SO2, and H2S over the study period was 17 µg/m3, 20 µg/m3, 13 µg/m3, 2 µg/m3, 2 µg/m3, respectively. The association for IQR increases of the pollutants and cardiovascular mortality were not statistically significant (confidence interval: 95%) at any time lag, with odds ratios near unity. Conclusion: The pollution concentration levels in Reykjavik are generally low in an international perspective, but peaks of pollutants, such as PM10, may exceed peaks occurring in other European cities. Previous studies have implied that air pollution in Reykjavik could increase consumption of medicament against asthma and angina pectoris. However, there were no short-term associations between air pollution and cardiovascular mortality in the present study, contrary to what has been found elsewhere.