Household polluting cooking fuels and intrinsic capacity among older population: A harmonized nationwide analysis in India and China

Household polluting cooking fuels, as an important changeable behavior, are related to various detrimental health effects among the elderly. There is limited research on the association between polluting cooking fuel use and intrinsic capacity (IC) as an indicator of healthy aging. This study aimed to evaluate the above-mentioned association in India and China, where polluting cooking fuel use is common. We enrolled 33,803 participants aged ≥60 years from two nationally representative studies: the Longitudinal Aging Study in India and the China Health and Retirement Longitudinal Study. Polluting cooking fuel use was defined as a self-report of using wood, coal, kerosene, crop residue, or dung. IC was measured by five aspects, including locomotion, cognition, vitality, sensory, and psychological capacity. The random-effects mixed linear regression and logistic regression with population weighting were performed. Multivariable-adjusted model and propensity score were used to adjust for potential confounders. A total of 47.54 % and 59.32 % of elderly adults reported primary cooking using polluting fuels in India and China, respectively. Using polluting cooking fuels was consistently associated with IC decline; particularly, cognitive capacity was the most susceptible domain. In India, participants using polluting fuels had a 1.062 (95 % confidence interval [CI]: 1.047–1.078) times risk for IC deficits, whereas more prominent results were observed in China (odds ratio [OR]: 2.040, 95 % CI: 1.642–2.533). Such harmful effects might be alleviated by transferring from polluting to clean fuels. Additionally, the duration of polluting fuel use was also positively associated with IC deficits. This study provided substantial public implications on healthy aging for the elderly population at a global scale, strengthening the importance of health education and policy efforts to accelerate the transition from polluting to clean fuels.