Association between indoor ventilation frequency and low muscle mass among older adults in China: a national cross-sectional research

Previous studies have established associations between indoor air pollution and loss of muscle mass. While indoor ventilation improves indoor air quality, its association with low muscle mass (LMM) remains unexplored. We investigated the association between indoor ventilation frequency (IVF) and LMM in older Chinese adults. Utilizing data from the China Longitudinal Healthy Longevity Survey (CLHLS), IVF was assessed via self-reported weekly window-opening frequency in each season of the past year. LMM was defined using appendicular skeletal muscle mass (ASM) prediction equations. Binary logistic regression models were employed to evaluate the association between IVF and LMM, with subgroup and sensitivity analyses conducted. After adjusting for covariates, participants with intermediate IVF (OR: 0.805; 95% CI: 0.669-0.969) and high IVF (OR: 0.818; 95% CI: 0.684-0.979) were 19.5% and 18.2% less likely to develop LMM, compared with participants with low IVF. The probability of LMM in the spring was 25.3% (OR: 0.747; 95% CI: 0.581-0.961) and 23.3% (OR: 0.767; 95% CI: 0.597-0.985) lower in the middle and high IVF elderly populations, respectively, whereas the probability of LMM in the spring was 36.5% (OR: 0.625; 95% CI: 0.474-0.824) and 34.1% (OR: 0.659; 95% CI: 0.501-0.868). The association between IVF and LMM was statistically significant (p < 0.05) in gender, age, residence, living arrangement, marital status, economic situation, work, smoking, drinking, exercise, cooking ventilation, life satisfaction, self-rated health, hypertension, diabetes, heart disease, dementia, and NO₂. Interaction analyses showed a significant interaction effect between the drinking subgroup and IVF (P for interaction < 0.05). Higher IVF is significantly associated with a lower risk of LMM. Optimizing ventilation practices may mitigate LMM burden in older adults, informing personalized health strategies.