Association of long-term exposure to PM_2.5 with hypertension prevalence and blood pressure in China: a cross-sectional study.

Abstract

Evidence of the effects of long-term fine particulate matter (PM_2.5) exposure on hypertension and blood pressure is limited for populations exposed to high levels of PM_2.5. We aim to assess associations of long-term exposure to PM_2.5 with hypertension prevalence and blood pressure, and further explore the subpopulation differences and effect modification by participant characteristics in these associations in China. We analysed cross-sectional data from 883 827 participants aged 35-75 years in the China Patient-Centred Evaluative Assessment of Cardiac Events Million Persons Project. Data from the monitoring station were used to estimate the 1-year average concentration of PM_2.5. The associations of PM_2.5 exposure with hypertension prevalence and blood pressure were investigated by generalised linear models, with PM_2.5 included as either linear or spline functions. The 1-year PM_2.5 exposure of the study population ranged from 8.8 to 93.8 µg/m³ (mean 49.2 µg/m³). The adjusted OR of hypertension prevalence related to a 10 μg/m³ increase in 1-year PM_2.5 exposure was 1.04 (95% CI, 1.02 to 1.05). Each 10 μg/m³ increment in PM_2.5 exposure was associated with increases of 0.19 mm Hg (95% CI, 0.10 to 0.28) and 0.13 mm Hg (95% CI, 0.08 to 0.18) in systolic blood pressure and diastolic blood pressure, respectively. The concentration-response curves for hypertension prevalence and systolic blood pressure showed steeper slopes at higher PM_2.5 levels; while the curve for diastolic blood pressure was U-shaped. The elderly, men, non-current smokers and obese participants were more susceptible to the exposure of PM_2.5. Long-term exposure to PM_2.5 is associated with higher blood pressure and increased risk of hypertension prevalence. The effects of PM_2.5 on hypertension prevalence become more pronounced at higher PM_2.5 levels. These findings emphasise the need to reduce air pollution, especially in areas with severe air pollution.