Short-term exposure to ozone and ECG abnormalities in China: A nationwide longitudinal study.

Ambient ozone (O) pollution has been associated with an increased risk of cardiovascular diseases. However, few studies have addressed the effect of O exposure on electrocardiogram (ECG) abnormalities, a subclinical indicator of early damage to the cardiovascular system. This study aimed to examine the association between short-term exposure to O and ECG abnormalities. We included 102,027 visits of 47,290 participants over 40 years old who had a normal ECG at baseline and then visited again at least once from the China National Stroke Screening Survey (CNSSS). Short-term ozone exposure concentrations were measured as averages of maximum daily 8-h O concentrations over the two weeks prior to ECG measurements. The generalized estimation equations models were used to evaluate the association between O exposure and ECG abnormalities. For every 10 µg/m increment in short-term O concentration, the odds ratio of any ECG abnormality was 1.055 (95% confidence interval [CI] 1.045-1.064). For ECG-diagnosed cardiac arrhythmia, the odds ratio was 1.062 (95% CI 1.052-1.072). A nonlinear analysis showed a sublinear relationship between O exposure and risk for ECG abnormalities. The association between O exposure and ECG abnormalities varied by subpopulation. Our study provided new epidemiological evidence on the association between short-term O exposure and ECG abnormalities. There is an urgent need to control ambient O pollution to prevent cardiovascular events.