目標：台灣有吸菸經驗的青少年約有25%變成穩定吸菸者，青少年吸菸已成為重要公共衛生議題。本研究探討2009年菸害防制新法實施，對台灣青少年吸菸及家庭二手菸暴露之效益，並探討影響青少年吸菸與家庭二手菸暴露之因素。方法：運用2004－2011年青少年吸菸行為調查（GYTS）資料庫，包含國中及高中生，以多變項邏輯式迴歸進行分析。結果：國中生與高中生吸菸率分別為7.1與13.7%，二手菸暴露率分別為46.66%與44.45%；多變項分析結果顯示新法顯著降低高中生家庭二手菸暴露風險26%－32%，高中生吸菸風險亦顯著降低65%；但國中生吸菸與家庭二手菸暴露可能性均無顯著差異。眾多影響因素中，同儕吸菸、對吸菸為正面意向的青少年較容易吸菸及暴露於家庭二手菸，而父母吸菸也使青少年家庭二手菸暴露風險升高。結論：菸害防制新法減少高中生吸菸風險與家中暴露於二手菸的風險。建議未來若欲減低青少年吸菸率，可著重於減輕青少年來自同儕、父母、及媒體構成之正面吸菸意向。

Objectives: Previous studies have found a downward trend in the age of onset of adolescent smoking in Taiwan. Among those adolescents who had tried smoking, one fourth became regular smokers. This study investigated the risk factors associated with adolescent smoking behavior and secondhand smoke (SHS) exposure at home after the implementation of the 2009 Taiwan Tobacco Hazards Prevention Act. Methods: The study utilized data from the 2004 -2011 Taiwan Global Youth Tobacco Survey. Multiple logistic regression analyses were performed to examine the impact of the 2009 Taiwan Tobacco Hazards Prevention Act and to identify the risk factors for adolescent smoking and SHS exposure at home. Results: After the Act was implemented, the risk of smoking by senior high students decreased by 26%-32%; the risk of their SHS exposure at home decreased by 65%. Peer smoking and holding positive beliefs about smoking were the key factors in adolescent smoking; parental smoking was also a key factor in adolescent SHS exposure. Conclusions: This study provided evidence that the 2009 Taiwan Tobacco Hazards Prevention Act reduced the risks of senior high students smoking and SHS exposure at home. The results suggested a need to lower the adult smoking rate and to control the positive attitude about smoking encouraged by peer smoking, parental smoking and the media in order to lessen the risk of smoking and SHS exposure.