A longitudinal study on the effect of PM2.5 components on blood pressure in the hypertensive patients from 2011 to 2019

Extensive research has established the link between PM_2.5 exposure and blood pressure (BP) levels among normal individuals. However, the association between PM_2.5 components and BP levels in hypertensive patients has not been fully explored. In this study, 12 971 hypertensive cases from Jinchang cohort (in Jinchang City, China) with nearly 9 years of follow-up were enrolled. Based on the linear mixed-effect model, the effects of fine particulate matter (PM_2.5) and five major components [sulfate (SO₄^2-), nitrate (NO₃^-), ammonium (NH₄⁺), black carbon (BC) and organic matter (OM)]on BP [systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP)]were evaluated by single-component model, component-joint model and component-residual model, respectively. A positive correlation was found between PM_2.5 as well as its components (SO₄^2-, NO₃^-, NH₄⁺, BC and OM) exposure and BP levels. The effects of SO₄^2-, BC and OM on BP were observed to be the most robust among the three models. Based on the results of interaction effects and stratified analysis, the effect of BC exposure on SBP, and the effect of PM_2.5 and its five components on PP were greater in female than in males. Compared with elderly hypertensive patients, OM had more significant effects on SBP, DBP and MAP in young and (or) middle-aged hypertensive patients. During the heating season, the effect of PM_2.5 and its components on BP was grater compared to the non-heating season. Meanwhile, PM_2.5 and its components have a greater influence on BP in patients with hypertension combined with diabetes. Therefore, the findings suggested that both PM_2.5 exposure and its components had a significant effect on BP in patients with hypertension. Women and young and middle-aged hypertensive patient were the sensitive population. The implementation of source control and reduction of PM_2.5 emission (mainly for SO₄^2-, BC and OM) may be of great significance to control BP level and could reduce the risk of cardiovascular disease in patients with hypertension.