Household Air Pollution, Physical Activity, and the Risk of Frailty Among Middle-Aged and Older Adults: A Cohort Study

OBJECTIVE: This study aims to explore the relationship among household air pollution, physical activity (PA), and the risk of frailty among middle-aged and older adults. DESIGN: Prospective cohort study. SETTING AND PARTICIPANTS: A total of 10,561 participants from the 2011-2020 China Health and Retirement Longitudinal Study (CHARLS) were included. METHODS: PA was assessed using the International Physical Activity Questionnaire (IPAQ), and household air pollution was measured based on cooking and heating. Frailty risk was evaluated using the frailty index (FI). Cox proportional hazards regression models were used for statistical analysis. RESULTS: During the follow-up, 1101 participants developed frailty. After adjusting for all covariates, compared with participants who consistently used solid fuels, transforming solid fuels to cleaner fuels for cooking [hazard ratio (HR), 0.671; 95% CI, 0.560-0.803] and heating (HR, 0.373; 95% CI, 0.292-0.479) reduced the risk of frailty by 32.9% and 62.7%, respectively. Conversely, transforming cleaner fuels to solid fuels for cooking increased the risk of frailty by 27.5% (HR, 1.275; 95% CI, 1.006-1.599). Sufficient PA for 3 to 4 years (HR, 0.658; 95% CI, 0.542-0.798) and for ≥5 years (HR, 0.490; 95% CI, 0.398-0.602) reduced frailty risk by 34.2% and 51.0%, respectively. Both transforming solid household fuels to cleaner household fuels with 3 or more years of sufficient PA and transforming cleaner household fuels to solid household fuels with 3 or more years of sufficient PA were significantly associated with lower frailty risk. CONCLUSIONS AND IMPLICATIONS: Both transforming solid household fuels to cleaner household fuels and maintaining sufficient PA for 3 or more years were significantly associated with lower risk of frailty. Conversely, transforming cooking-related cleaner fuels to cooking-related solid fuels can increase frailty risk. In addition, 3 or more years of sufficient PA can superimpose the benefits of transforming solid household fuels to cleaner household fuels, offsetting the negative effects of transforming cleaner household fuels to solid household fuels.