Background:
Secondhand smoke(SHS) is known to be one of the major causes of illness and death. Children and adolescents in smoking households are more likely to be exposed to SHS. They have a high incidence of upper respiratory infection and other respiratory symptoms. Also, disparity in SHS exposure from socioeconomic status could be main reason for health inequalities. Even if SHS has been shown to be a major contributor to health inequalities, there were few previous studies considering SHS exposure and socioeconomic status in South Korea. The aim of this study is to investigate the association between socioeconomic status and adolescent SHS exposure at home.

Methods:
The data was based on the 12th Korea Youth Risk Behavior Web-based Survey(2016) from the Ministry of Education and of Health and Welfere of Korea containing case of 59,095 non-smoking adolescent aged 12 to 18 years. The dataset was analyzed using descriptive statistics and logistic regression.

Results:
The adolescent who reported SHS exposure at home accounted for 28.5% among the study population. It was more likely to be exposed to SHS stepwise from high to low household income level(χ²=356.80, p< 0.001). The lower level of parental education, adolescents were more likely to be exposed to SHS(χ²=568.59, p< 0.001). The low(OR=1.20, CI=1.09-1.32) and very low(OR=1.23, CI=1.04-1.44) income level groups were significantly associated with adolescent SHS exposure. The group of whose mother´s education was higher than college was less likely to be exposed to SHS than the group of lower than middle school(OR=0.84, CI=0.78-0.99).

Conclusions:
Inequalities in SHS exposure exist among adolescent in South Korea. Especially in low income group, adolescent were more likely to be exposed to SHS at home. This study implies that public health strategies are urgently needed to protect vulnerable social group from SHS exposure.