Associations of long-term exposure to ambient PM2.5 and its constituents with risk of incident hypertension in rural China

Abstract

We investigated the associations between long-term exposure to fine particulate matter (PM₂.₅) and its chemical constituents with the risk of incident hypertension in a prospective cohort of 17,380 adults from the Rural Deqing Cohort Study. Annual concentrations of PM₂.₅ and six major constituents were estimated using a satellite-based statistical model. Stratified Cox proportional hazard models were applied to evaluate the associations between pollutants exposure and hypertension incidence. Quantile-based g-computation was employed to assess the joint effects of PM₂.₅ constituents and determine their relative contributions. Over a mean follow-up period of 9.17 years, 4073 participants developed incident hypertension. Participants in the highest quartile of PM₂.₅ exposure had a significantly increased risk of hypertension compared to those in the lowest quartile (hazard ratio [HR]: 1.75; 95 % confidence interval [CI]: 1.51–2.03). Each 10-μg/m³ increase in PM₂.₅ was significantly associated with a 44 % higher risk of incident hypertension (HR:1.44; 95 % CI:1.31–1.59). Similar positive associations were observed for individual PM₂.₅ constituents. Among them, ammonium contributed the most to the overall mixture effect (82.9 %) among all individual constituent. Stronger associations were observed among men and younger adults. Our findings suggests that long-term exposure to ambient PM₂.₅ and its constituents, particularly ammonium, increases the risk of incident hypertension. Subpopulations including men and younger adults may be more susceptible to the adverse cardiovascular effect of air pollution.