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To compare the effects of short-term exposure to particulate matter (PM) with different particle sizes on first-ever stroke risk in the middle-aged and elderly Chinese population. Health information was collected from the China National Stroke Screening Survey (CNSSS) from March 1, 2013, to April 10, 2015. Ambient exposures to PM 1 , PM 2.5 , and PM 10 were obtained from ChinaHighAirPollutants (CHAP) Grid data. Case-crossover design was used to estimate the increase of first-ever stroke risk per 10 μg/m3 increase in ambient exposures to different size particles. We used distributed lag linear model (DLM) to estimate the hysteresis effects of particle exposures. In addition, in order to assess the effect modification of long-term exposure, we did a stratified analysis using median exposure as the dividing line. We included 1326 first-ever stroke events from 242 communities in the present study. We found that effects on first-ever stroke risk increased with the decrease in particle size. The percent increases of first-ever stroke risk increased by 6.6% (95% CI: 1.4, 12.0), 3.3% (95% CI: 0.5, 6.1), and 0.6% (95% CI: -1.2, 2.6) per 10 g/m3 increases in PM 1 , PM 2.5 , and PM 10 exposures in lag 0–2 days, respectively. Furthermore, the cumulative effect of PM on first-ever stroke reached its peak at distinct time points under different layers of long-term PM exposure. In areas with low PM exposure, the cumulative effects of the three kinds of particles on stroke reached their peak in lag1 day, while the cumulative effect peaked in lag3 day in areas with high PM exposure. This study found that smaller particles had a stronger short-term effect on first-ever stroke. We also found that people in areas with long-term exposures to lower levels were more sensitive to short-term exposures. These results have public health significance for stroke prevention and air pollution reduction. [Display omitted] • The effects of PM on first-ever stroke in a large area were evaluated. • The impacts of PM increase with decreasing particle size. • The short-term effects of PM were larger in areas with lower long-term exposure levels. [ABSTRACT FROM AUTHOR]

Ambient ozone (O 3) pollution has been associated with an increased risk of cardiovascular diseases. However, few studies have addressed the effect of O 3 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 3 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 3 concentrations over the two weeks prior to ECG measurements. The generalized estimation equations models were used to evaluate the association between O 3 exposure and ECG abnormalities. For every 10 µg/m3 increment in short-term O 3 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 3 exposure and risk for ECG abnormalities. The association between O 3 exposure and ECG abnormalities varied by subpopulation. Our study provided new epidemiological evidence on the association between short-term O 3 exposure and ECG abnormalities. There is an urgent need to control ambient O 3 pollution to prevent cardiovascular events. [Display omitted] • Electrocardiogram abnormality as a subclinical indicator can reflect the early injury of cardiovascular system. • Short-term exposure to ozone is positively associated with ECG abnormalities in a large Chinese population. • Cardiovascular diseases should be prevented by reducing the occurrence of ECG abnormalities. [ABSTRACT FROM AUTHOR]