Active smoking and exposure to secondhand smoke and their relationship to depressive symptoms in the Korea national health and nutrition examination survey (KNHANES)

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Abstract Background The relationship between tobacco smoking, including secondhand smoking, and depression has been assessed. The purpose of this study was to evaluate the association between secondhand smoking among current, former and never smokers and depressive symptoms. For secondhand smoking, gender differences and sources of exposure were examined. Methods Data from 34,693 participants from the fourth and fifth Korean Health and Nutritional Examination Survey (2007–2012) were analyzed in 2014. Self-reported exposure to active (current, former or never) and secondhand smoking and depressive symptoms experienced during the past year were analyzed using logistic regression. The dose–response relationship between duration of secondhand smoke exposure and depression was assessed with stratification by gender and sources of exposure (at home only, at the workplace only or both). Results Regardless of their smoking status, all women who had secondhand smoke exposure at home reported more depressive symptoms than non-smoking women without any exposure to secondhand cigarette smoking (OR 1.43, 95 % CI 1.04–1.96 for current smokers; OR 2.32, 95 % CI 1.04–5.16 for former smokers; OR 1.25, 95 % CI 1.08–1.43 for never smokers). There was also a significant dose–response pattern (p-trend