Long-term exposure to traffic-related air pollution and the risk of death from hemorrhagic stroke and lung cancer in Shizuoka, Japan

A number of studies have linked exposure to long-term outdoor air pollution with cardiopulmonary disease; however, the evidence for stroke is limited. Furthermore, evidence with the risk for lung cancer (LC) is still inconsistent. We, therefore, evaluated the association between long-term exposure to traffic-related air pollution and cause-specific mortality. Individual data were extracted from participants of an ongoing cohort study in Shizuoka, Japan. A total of 14,001 elderly residents completed questionnaires and were followed from December 1999 to January 2009. Annual individual nitrogen dioxide (NO2) exposure data, as an index for traffic-related exposure, were modeled using a Land Use Regression model and assigned to the participants. We then estimated the adjusted hazard ratios (HRs) and their confidence intervals (CIs) associated with a 10 mu g/m(3) elevation in NO2 for all-cause or cause-specific mortality using time-varying Cox proportional hazards models. We found positive associations of NO2 levels with all-cause (HR = 1.12, 95% CI: 1.07-1.18), cardiopulmonary disease (HR = 1.22, 95% CI: 1.15-1.30), and LC mortality (HR = 1.20, 95% CI: 1.03-1.40). Among cardiopulmonary disease mortality, not only the risk for ischemic heart disease (HR = 1.27,95% CI: 1.11-1.47) but also the risks for stroke were elevated: intracerebral hemorrhage (HR = 1.28,95% CI: 1.05-1.57) and ischemic stroke (HR = 1.20,95% CI: 1.04-1.39). The present study supports the existing evidence that long-term exposure to traffic-related air pollution increases the risk of cardiopulmonary as well as LC mortality, and provides additional evidence for adverse effects on intracerebral hemorrhage as well as ischemic stroke. (C) 2012 Elsevier B.V. All rights reserved.