This study investigated the association between long-term exposure to multiple ambient air pollutants and the risk of heart disease among middle-aged and older adults in China, and assessed the robustness of results as well as potential population heterogeneity through sensitivity and stratified analyses. We used nationally representative data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 9,403 participants were included in the cross-sectional analysis, and 7,750 participants free of heart disease at baseline were prospectively followed for 9 years (2011-2020). Annual average concentrations of PM₁, PM₂.₅, PM₁₀, NO₂, and O₃ were estimated using the high-resolution spatiotemporal China High Air Pollution (CHAP) model and assigned to participants based on city-level geocoded residential information. Logistic regression was applied for cross-sectional analyses, while Cox proportional hazards models were used for longitudinal analyses with stepwise adjustment for demographic, lifestyle, and clinical covariates. Multi-pollutant models and sensitivity tests were additionally performed. In the cross-sectional analysis, only PM₁₀ was significantly associated with prevalent heart disease (OR = 1.002, 95% CI: 1.000-1.004, P = 0.019). In the longitudinal analysis, each 1-SD increase in PM₁₀ and PM₂.₅ was associated with a 22.3% (HR = 1.223, 95% CI: 1.163-1.285) and 15.1% (HR = 1.151, 95% CI: 1.090-1.215) higher risk of incident heart disease, respectively (both P < 0.001). PM₁ and NO₂ were also positively associated with incident risk. For O₃, no significant association was observed in single-pollutant models (HR = 0.957, 95% CI: 0.908-1.009), but a negative association emerged after simultaneous adjustment for NO₂ in multi-pollutant models (HR = 0.779, 95% CI: 0.700-0.867), indicating high sensitivity to co-pollutant adjustment and exposure windows. Subgroup analyses suggested higher risks among women, rural residents, and individuals with lower education, although no significant interactions were detected. Long-term exposure to PM₁, PM₂.₅, and PM₁₀ was robustly associated with an increased risk of heart disease, and this study provides novel epidemiological evidence for PM₁. These findings underscore particulate matter pollution as a modifiable risk factor and highlight the importance of targeted public health strategies for susceptible populations.
