Household air pollution, adherence to a healthy lifestyle, and risk of cardiometabolic multimorbidity: Results from the China health and retirement longitudinal study

The adverse health effects of household air pollution have been widely explored, but few studies have evaluated the effects of household air pollution on the risk of cardiometabolic multimorbidity (CMM), a pressing public health concern worldwide. Thus, we aimed to investigate whether exposure to household use of polluting fuels is associated with morbid CMM and, if so, whether a healthy lifestyle could mitigate this association.In this prospective, nationwide representative cohort of the China Health and Retirement Longitudinal Study (CHARLS), participants free of CMM (defined as the coexistence of 2 or more of the following: heart disease, stroke, and diabetes or high blood sugar) were included in 2011-2012 and followed for CMM incidence until 2018. Household air pollution was measured as the use of solid fuels for cooking and heating. The healthy lifestyle score was determined by six factors, physical activity, smoking, body mass index, total cholesterol, blood glucose, and blood pressure, and categorized into three groups (unhealthy, 0-1 factors; intermediate, 2-4; and healthy, 5-6). Cox proportional hazards models investigated associations between household air pollution and incident CMM. The potential modifier effect of a healthy lifestyle score was tested through stratified analyses.Among 7125 eligible participants, 239 incident cases of CMM were identified over a median follow-up of 7.0 years. After adjustment for potential confounders, the use of solid household fuels for heating was associated with more significant hazards of CMM (adjusted hazard ratio [HR] 1.71, 95 % confidence interval [CI] 1.28 to 2.28), while use for cooking (HR, 1.14; 95 % CI, 0.85 to 1.52) was not. Compared with participants in the unhealthy group, those in the healthy and intermediate groups had considerably lower CMM risk, with adjusted HRs (95 % CI) of 0.17 (0.09 to 0.31) and 0.39 (0.29 to 0.53), respectively, regardless of the household air pollution category. Importantly, when participants adhered to a healthy lifestyle, exposure to household air pollution was no longer significantly associated with a higher risk of CMM (adjusted HR 1.77, 95 % CI 0.51 to 6.12; P = 0.369).Household usage of polluting fuels was significantly associated with a higher risk of CMM, and adherence to a healthy lifestyle may mitigate this adverse effect. From a broader perspective, our findings underscore the importance of public health policies and interventions targeting multiple exposures (air pollution, physical activity, smoking, etc.) in enhancing the prevention of detrimental cardiometabolic health effect.