Association Between Household Cooking Fuel Type and Circadian Syndrome Among Middle‐Aged and Older Adults in China: The First Longitudinal Evidence From CHARLS

Indoor air pollution from household cooking fuel combustion constitutes a major environmental risk factor threatening global health. Nevertheless, the association between the utilization of household cooking fuel and circadian syndrome (CircS) remains unclear among middle‐aged and older populations in China. This study was aimed at investigating the association between household cooking fuel type and CircS. Using prospective data from the China Health and Retirement Longitudinal Study, a total of 1907 middle‐aged and older adults were included in the analysis. Binary logistic regression models were employed to evaluate the association between household cooking fuel type and CircS. Furthermore, subgroup, interaction, mediation, and sensitivity analyses were conducted to assess potential effect modification, explore underlying pathways, and examine the robustness of the findings. The results showed that, compared with clean fuels, exposure to solid fuel among middle‐aged and older adults was significantly associated with a lower incidence of CircS (OR = 0.656, 95% CI, 0.502–0.857). Upon further stratification of solid fuels, we discovered that participants using crop residues and wood combustion had a significantly reduced incidence of CircS (OR = 0.656, 95% CI, 0.496–0.869). Subgroup analysis demonstrated that the association between household cooking fuel and CircS was only statistically significant in specific subgroups of middle‐aged and older adults, including males, those aged ≥ 60 years, and married individuals ( p < 0.05). Results of mediation analysis indicated that triglycerides, high‐density lipoprotein, diastolic blood pressure, and systolic blood pressure mediated 6.95%, 22.92%, 10.63%, and 9.59% of the effect of household cooking fuel on CircS, respectively. Fasting blood glucose masked 2.53% of the impact of the use of solid fuel on CircS. These findings illuminate novel trajectories for the prompt detection and targeted mitigation of CircS and furnish robust empirical support for advancing public health inquiry and precision‐oriented health governance.