Long-Term Effects of Ambient Particulate Matter (With an Aerodynamic Diameter ≤2.5 μm) on Hypertension and Blood Pressure and Attributable Risk Among Reproductive-Age Adults in China

Background-Epidemiological evidence on the association between long-term exposure to ambient fine particulate matter (with an aerodynamic diameter <= 2.5 mu m; PM2.5) and hypertension is mixed. We investigated the long-term association between ambient fine particles and hypertension in reproductive-age adults. Methods and Results-This analysis included 39 348 119 reproductive-age (20-49 years) participants from the National Free Preconception Health Examination Project from April 22, 2010 to December 31, 2015 across China. The estimation of annual average ambient PM2.5 concentrations for each community was realized through using satellite-based spatial statistical models. Linear mixed models and 2-level logistic regressions adjusted for potential confounders with natural cubic splines were used to investigate the shape of PM2.5-blood pressure and PM2.5-hypertension, respectively. The effect modification by sex, obesity, smoking status, age, diabetes mellitus, urbanity, race, and region was also taken into account. The concentration-response relationship between PM2.5 and hypertension was nonlinear, with a threshold concentration of 47.9 mu g/m(3). The odds ratio of hypertension related to a 10-mu g/m(3) increase in PM2.5 above threshold was 1.010 (95% confidence interval, 1.007-1.012). A 10-mu g/m(3) increase in PM2.5 above threshold corresponded to a 0.569 (95% confidence interval, 0.564-0.573) mm Hg elevation in systolic blood pressure and a 0.384 (95% confidence interval, 0.381-0.388) mm Hg elevation in diastolic blood pressure. There were 2.3% (95% confidence interval, 2.2%-2.4%) of the hypertension cases that could be attributed to PM2.5 exposures in reproductive-age adult populations. Conclusions-Long-term exposures to PM2.5 above certain levels might increase population risk for hypertension and might be responsible for China's avoidable hypertension burden in reproductive-age adults.