Does passive smoking at home lead to depression among older people in China?

BACKGROUND: This paper was carried out based on two motivations: (a) prior studies achieved mixed results regarding the effect of passive smoking on depression; and (b) studies on the impacts of passive smoking usually neglect effects on older people. In our paper, we studied the causal effect of passive smoking at home on depression among older people aged 60 years and older in China with a longitudinal study. METHODS: In assessing the causal relationship, we developed a fixed-effects instrumental variable method using an exogenous variable-health consciousness and the smoking status of parents-as instruments of smoking status. We used data from the China Health and Retirement Longitudinal Study (CHARLS), which provides a national, high-quality, and longitudinal household survey of people aged 45 years and older. RESULTS: Our empirical results reveal that passive smoking at home increased the depressive symptoms of older people, regardless of their smoking status. Moreover, the impact of passive smoking on depression is larger for nonsmokers than smokers. Additionally, the health consciousness and smoking status of parents are effective instrumental variables. CONCLUSIONS: This paper calls for governments and medical institutions to pay more attention to the health of older people and their need for healthy living environments.