Long-term effects of PM and its components on incident hypertension among the middle-aged and elderly: a national cohort study.

Background: The long-term health effects of fine particulate matter (PM) on hypertension remain incomprehensive. We evaluated the relationship of PM and its components with hypertension incidence in middle-aged and elderly adults.

Methods: We utilised data from the China Health and Retirement Longitudinal Study collected between 2011 and 2018. We obtained annual modelled data from the dataset of Tracking Air Pollution in China, including black carbon (BC), sulphate (SO), organic matter (OM), ammonium (NH), and nitrate (NO). Time-varying Cox models and quantile g-computation models were employed to explore the associations. Exposure-response curves were portrayed to investigate potential non-linear effects.

Results: We enrolled 7,032 individuals with a mean age of 57.14 (range: 45-95) years. Over 36,997 person-years of follow-up (average time: 5.26 years), 3,119 individuals suffered from hypertension. With per interquartile range increment, the hazard ratios and 95% confidence intervals (CIs) of PM (3.82 [95% CI: 3.48-4.18]), BC (4.17 [95% CI: 3.54-4.92]), SO (4.24 [95% CI: 3.50-5.12]), OM (3.76 [95% CI: 3.14-4.50]), NH (3.20 [95% CI: 2.91-3.52]), and NO (1.94 [95% CI: 1.77-2.13]) were discovered with lag 1 year. And the mixed effect was 18.0% [95% CI: 16.8%-19.2%], which was mainly driven by BC (66.0%) and SO (34.0%). Approximate J-shaped exposure-response relationships were revealed.

Conclusions: The positive associations of long-term exposure to PM and its components with hypertension incidence were discovered in adults aged ≥ 45 years. Controlling the emissions of PM components, especially BC and SO, could alleviate the burden of hypertension.