Secondhand smoke exposure (SHSE) is prevalent in China and might affect mental health, but research on older adults is limited. A study analyzed data from 7,958 nonsmoking participants aged 50 and older in the Guangzhou Biobank Cohort Study to explore the link between SHSE and depressive symptoms. SHSE was evaluated through structured interviews, measuring cumulative exposure over time and by context, such as home and workplace.

Results indicated that higher cumulative SHSE correlated with increased severity of depressive symptoms, as measured by the 15-item Geriatric Depression Scale (GDS-15). Participants exposed to SHSE for more than five years had significantly higher GDS-15 scores compared to those with less than two years of exposure. Workplace exposure showed a notable association with elevated GDS-15 scores, while the impact of home exposure was less significant after adjusting for other factors. More smokers and greater frequency of SHSE at home were also linked to higher GDS-15 scores. No correlation was found with childhood SHSE.

The findings suggest that prolonged SHSE, especially in workplace settings, may be associated with increased depressive symptoms in older adults. Further research is needed to clarify the nature of this relationship.