Cardiovascular morbidity and ambient air pollution in Atlanta, 1993-2000

Although substantial evidence supports an association between cardiovascular disease (CVD) and ambient air pollution, the specific cardiac response and the characteristics of particulate matter (PM) and gaseous copollutants involved in this relationship are not well understood. Three studies of cardiovascular conditions were initiated to take advantage of a unique source of ambient air quality data from an innovative monitoring station located in downtown Atlanta, Georgia, which collected detailed information on particle chemical composition and physical characteristics, as well as a comprehensive suite of gaseous pollutants. Two time-series studies examined the association between CVD emergency department (ED) visits and ambient air pollution levels in Atlanta. One study utilized ED and air quality data collected during the 25-month time period of the operation of the downtown monitor from August 1, 1998, to August 31, 2000, while the other used air quality measurements obtained from state monitoring networks for the previous 5 years, from January 1, 1993, to July 31, 1998. These time-series studies were the first air pollution epidemiology studies to use ED visits as a measure of cardiovascular morbidity. A third study was developed to examine the occurrence of ventricular arrhythmias in a patient population with automatic implantable cardioverter defibrillators (AICD) for the time period January 1, 1993, to August 31, 2000. The electronic devices, implanted in patients at high risk of sudden cardiac death and ventricular tachycardia, detect arrhythmias and convert the heart back to normal sinus rhythm using electric pulses or shocks, as needed. Information from these devices regarding the date and time of tachyarrhythmic events provided a novel source of cardiac response data. In each study, associations between ambient concentrations of gaseous and particulate air pollutants and cardiovascular conditions of interest were observed. Overall, results from the three studies suggest that pollutants generated from mobile sources may play an important role. These studies provide insight into the complex relationship between cardiovascular morbidity and ambient air pollution by contributing information on the potential health effects of gaseous pollutants and PM and strengthening the coherence of evidence across cardiac outcome measures.