Trends in Spatiotemporal Exposure to Air Pollutants and Adult Cardiovascular Emergency Room Visits in the Greater Pittsburgh, Pennsylvania, USA

Abstract

Introduction
The acute effects of air pollution and cardiovascular disease (CVD) have been studied, but very few studies have focused on spatiotemporally
modeled exposure to air pollutants at the population level. This study aims to examine the short-term association
of fine particulate matter (PM2.5), Ozone (O3), Nitrogen Dioxide (NO2) and Sulfur Dioxide (SO2) and CVD emergency room
visits (ERV) in Allegheny County for a 13-year period using a case-crossover study design.
Aim
We sought to estimate the effects of acute exposure to these four pollutants adjusting for temperature on CVD ERV and to compare
outcomes in 1999-2005 compared to 2006-2011.
Methods
Land-use regression was used to model the ground level exposures to PM2.5, O3, NO2 and SO2. CVD ER visits were requested
from the local hospitals of the two health networks in Allegheny County, which operate the majority of the ER services. The
discharge International Classification of Diseases-9 (ICD-9) codes were used to identify the CVD cases and CVD subgroups. We
linked the Zone Improvement Plan (ZIP) code level air pollution data with the patients’ ZIP code (residence) to determine the
individual level exposure estimation of both case days and control days. Conditional logistic regression with multi-pollutant and
distributed lags of 0-3-days was applied to estimate the effect of acute exposure of these pollutants to CVD ER visits (ERV),
adjusting for temperature.
Results
In the overall analyses, for every interquartile increase of O3 exposure (25.52 ppb), there was a 6.6% (95% CI: 0.8%-12.7%)
increase in the odds of an acute myocardial infarction ERV. This was consistent across both time periods. Among women and
Black ERV, we observed an association of PM2.5 with acute myocardial infarction, and with ischemic heart disease. Some of these
associations persisted in the later years of the study period. The gaseous pollutants (NO2, SO2 and O3) were shown to increase risk
of cardiovascular events in both time periods.
Conclusion
We found an association of PM2.5 and NO2 with CVD ER visits, and this association persisted in the stratified analyses, as well as in
the later years with lower exposure levels. The findings suggest that further actions to reduce the pollution level in this area should
be taken. Ozone and NO2 were related to increased risk for all CVD, ischemic heart disease (IHD) and acute myocardial infarction
(AMI) underscoring the importance of gaseous pollutants and their effect on coronary heart disease (CHD) risk.