Secondhand smoke exposure and mental health in adults: a meta-analysis of cross-sectional studies

Purpose Previous studies assessing secondhand smoke (SHS) and risk of mental health problems have yielded inconsistent results. We performed a meta-analysis to statistically assess the association between SHS exposure, depressive symptoms and psychological distress among adults. Methods A systematically search of Pubmed (1946–2015) and EMBASE (1976–2015) was conducted and supplemented by bibliographies of all retrieved articles to find additional relevant citations. Odds ratios (OR) and associated 95 % confidence interval (CI) of each eligible study were extracted and pooled in our meta-analysis. Results A total of 11 studies comprising 86,739 participants met the inclusion criteria. A random-effect model was used in meta-analysis since considerable heterogeneity was expected. Our results indicate that SHS exposure was significantly associated with depressive symptoms (OR 1.60, 95 % CI 1.35–1.90) and psychological distress (OR 1.32, 95 % CI 1.11–1.56). Conclusion Exposure to SHS among non-smoker is associated with depressive symptoms and psychological distress, emphasizing the significance of reducing SHS exposure at a population level.