Cumulative air pollution exposure and cardiometabolic multimorbidity in Chinese middle-aged and older adults with sex-specific associations and triglyceride-glucose index mediation

The long-term associations between cumulative air pollution exposure and cardiometabolic multimorbidity (CMM) remain unclear. This study used data from the China Health and Retirement Longitudinal Study (CHARLS) and the China High Air Pollutants (CHAP) dataset. Five-year cumulative exposure to NO 2 , PM 1 , PM 2.5 , PM 10 , and O 3 was estimated using the area under the curve (AUC) method. CMM was defined as having two or more conditions among diabetes, heart disease, and stroke. Cox proportional hazards models, along with interaction and mediation analyses, were employed to investigate sex-specific associations between air pollution and CMM, as well as the mediating role of the triglyceride-glucose (TyG) index. Cumulative exposure to NO 2 , PM 1 , PM 2.5 , and PM 10 was significantly associated with increased CMM risk in women (HRs: 1.94, 1.99, 1.52, 1.28), with weaker associations in men. Interaction analyses indicated that women were more susceptible to air pollution. Mediation analyses suggested that the TyG index may partially account for these associations, with estimated proportions mediated ranging from 4 to 8% in women and from 8% to 16% in men. Long-term air pollution exposure was associated with an increased risk of CMM, particularly among women. The TyG index may partially account for these associations, suggesting a potential role of insulin resistance and the importance of sex-specific approaches to CMM prevention.