Association of PM_2.5, O₃ and greenness exposure with risk of cardiometabolic multimorbidity: a prospective cohort study

There is less evidence on the association between long-term PM_2.5, O₃, greenness exposure and cardiometabolic multimorbidity (CMM), and the aim of this study was to investigate the combined effects of PM_2.5, O₃ and greenness exposure on the risk of developing CMM.Our findings demonstrated that a 10 µg/m³ rise in PM_2.5 concentration led to a 23.8% increased CMM risk (HR = 1.238, 95%CI: 1.202,1.275). A 0.1 increase in NDVI reduced CMM risk by 18.9% (HR = 0.811, 95% CI: 0.779,0.845). A 10 µg/m³ O₃ concentration increase surprisingly lowered CMM risk by 30.8% (HR = 0.692, 95% CI: 0.649,0.738). Positive interactions were seen between high PM_2.5+low O₃ and low O₃ + low NDVI, while high PM_2.5+low NDVI had negative interactions regarding CMM. PM_2.5 mediated the link between NDVI and CMM, heart disease, and stroke.This study emphasizes that long-term high PM_2.5 exposure ups CMM risk in Chinese middle-aged and older adults, yet NDVI exposure reduces it, with PM_2.5 as a mediator. The O₃-CMM relationship remains unclear.