Long-term exposure to ozone and cardiovascular mortality in a large Chinese cohort

Abstract

Background: Evidence for the association between long-term exposure to ozone (O3) and cause-specific cardiovascular disease (CVD) mortality is inconclusive, and this association has rarely been evaluated at high O3 concentrations. Objectives: We aim to evaluate the associations between long-term O3 exposure and cause-specific CVD mortality in a Chinese population. Methods: From 2009 to 2018, 744,882 subjects (median follow-up of 7.72 years) were included in the CHinese Electronic health Records Research in Yinzhou (CHERRY) study. The annual average concentrations of O3 and fine particulate matter (PM2.5), which were estimated using grids with a resolution up to 1 × 1 km, were assigned to the community address for each subject. The outcomes were deaths from CVD, ischemic heart disease (IHD), myocardial infarction (MI), stroke, and hemorrhagic/ischemic stroke. Time-varying Cox model adjusted for PM2.5 and individual-level covariates was used. Results: The mean of annual average O3 concentrations was 68.05 μg/m3. The adjusted hazard ratio per 10 μg/m3 O3 increase was 1.22 (95% confidence interval [CI]: 1.13–1.33) for overall CVD mortality, 1.08 (0.91–1.29) for IHD, 1.21 (0.90–1.63) for MI, 1.28 (1.15–1.43) for overall stroke, 1.39 (1.16–1.67) for hemorrhagic stroke and 1.22 (1.00–1.49) for ischemic stroke, respectively. The study showed that subjects without hypertension had a higher risk for CVD mortality associated with long-term O3 exposure (1.66 vs. 1.15, p = 0.01). Conclusions: We observed the association between long-term exposure to high O3 concentrations and cause-specific CVD mortality in China, independent of PM2.5 and other CVD risk factors. This suggested an urgent need to control O3 pollution, especially in developing countries.

Keywords

• Ozone
• Long-term exposure
• Cardiovascular disease
• Mortality
• Chinese