Using spatio-temporal modeling for exposure assessment in an investigation of fine particulate air pollution and cardiovascular mortality

Background: U.S. urban air quality has improved dramatically over the past decades. We evaluated acute effects of fine particulate matter (PM2.5) on cardiovascular (CVD) mortality among residents of Allegheny County in SW Pennsylvania (1999-2011) using spatio-temporal modeling of air pollutants (AP) to reduce misclassification error in exposure assessment. Methods: Spatio-temporal kriging of daily PM2.5 and ozone (03) was used to produce daily exposure estimates at the residence ZIP code. Time-stratified case-crossover analysis was conducted to examine short-term effects of PM2.5 on CVD mortality, adjusting for 03 and apparent mean temperature. We studied both single and distributed lags for days 0-5. All CVD mortality and subcategories of ischemic heart disease (IHD), acute myocardial infarction, cerebrovascular disease, peripheral vascular disease (PVD), heart failure and cardiac arrhythmia were examined. Results: A total of 62,135 deaths were identified. We found significant associations of PM2.5 with IHD and PVD mortality at lag day 5: (2.1% (95% CI, 0.2-4.1%) and (7.6%, 95% CI, 0.05-15.7%) per 10 mu g/m(3) increase of PM2.5 in single lag models and for IHD in distributed lag models. There were no statistically significant associations with PM2.5 for any of the other outcomes. Conclusions: The application of finer scale geographically resolved AP exposures made it possible to study acute effects of PM2.5 on CVD mortality in a large metropolitan area. Our study results demonstrated the continued presence of a dose response relationship of increased risk of CVD mortality within this lower range of PM2.5 exposure. (C) 2016 Elsevier Inc. All rights reserved.