Associations of long-term exposure to ambient PM₁ with hypertension and blood pressure in rural Chinese population: The Henan rural cohort study

Background: The epidemiological evidence on relationships between long-term exposure to particulate matter and hypertension and blood pressure has been inconclusive. Limited evidence was available for particulate matter with an aerodynamic diameter ≤ 1 μm (PM₁)in rural areas of developing countries. Objective: This study aimed to investigate the associations between long-term exposure to PM₁ and hypertension and blood pressure among rural Chinese population. Methods: This study included 39,259 participants who had completed the baseline survey from Henan Rural Cohort. Participants' exposure to PM₁ was assessed by a satellite-based spatiotemporal model. The binary logistic regression model was used to examine the association between long-term PM₁ exposure and hypertension, and multivariable linear regression model was used to investigate the associations between long-term PM₁ exposure and systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP)and pulse pressure (PP). Moreover, we examined potential effect modifications by demographic, lifestyle and diet factors. Results: The mean concentration of PM₁ for all participants during the 3-year before baseline survey was 59.98 μg/m³. Each 1 μg/m³ increase in PM₁ concentration was significantly associated with an increase of 4.3% [Odds ratio(OR)= 1.043, 95% confidence interval(CI): 1.033, 1.053]in odds for hypertension, an increase of 0.401 mm Hg (95% CI, 0.335, 0.467), 0.328 mm Hg (95% CI, 0.288, 0.369), 0.353 mm Hg (95% CI, 0.307, 0.399)and 0.073 mm Hg (95% CI, 0.030, 0.116)in SBP, DBP, MAP and PP, respectively. Further stratified analyses showed that the effect of PM₁ on hypertension and blood pressure could be modified by sex, lifestyle and diet. Conclusions: This study suggests that long-term exposure to ambient PM₁ increases the risk of hypertension and is associated with elevations in blood pressure in rural Chinese adults, especially in male and those with unhealthy habits.