Long-term exposure to air pollutants with cardiometabolic multimorbidity and mediating role of atherogenic index of plasma and triglyceride-glucose index

Air pollution, linked to dyslipidemia and insulin resistance, is an important risk factor for cardiometabolic multimorbidity (CDM). However, the extent to which air pollutant is associated with CDM via glycolipid indicators of the atherogenic index of plasma (AIP) and triglyceride glucose (TyG) index remains unknown. Moreover, no study has assessed whether these associations varied by residential environmental characteristics. Using a nationally cross-sectional study of 7742 individuals aged ≥45 years from 125 Chinese cities, we investigated the association of air pollution with AIP, TyG index, and CDM. Annual particulate matter (PM) with aerodynamic diameters ≤10 μm (PM₁₀), ≤ 2.5 μm (PM_2.5), ≤ 1 μm (PM₁), nitrogen oxide, and sulfur dioxide exposure was estimated using spatiotemporal models. Multilevel random intercept models were applied to assess two-year air pollutant exposure with CDM, probing the role of AIP and TyG index through mediation analysis. Stratified analyses examined the modifiers by demographics and residential environmental variables. Annual PM₁₀, PM_2.5, and PM₁ exposure were associated with CDM, with the odds ratio of 1.06 (95 % CI: 1.01-1.11) for PM₁₀, 1.10 (1.01-1.20) for PM_2.5, and 1.24 (1.04-1.46) for PM₁. Both AIP and TyG index mediated the association of PM₁₀ or PM₁ with CDM, with a mediation proportion varying from 8.0 % to 18.0 %. The association was stronger in older adults and solid fuel users. This study suggests that the association of air pollution with CDM is partly explained by the AIP and TyG index, underscoring the value of improving air quality to prevent CDM in public health.