Division of Environmental and Preventive Medicine, Department of Social Medicine, Faculty of Medicine, Tottori University, Tottori, Japan.
National Institute of Alcoholism, Kurihama National Hospital, Kanagawa, Japan.
JAMA Netw Open. 2023 Oct 2;6(10):e2338166. doi: 10.1001/jamanetworkopen.2023.38166.
Secondhand smoke is a substantial risk factor for youth health globally, including in Japan, where tobacco control policies should be reassessed.
To assess trends in the prevalence of secondhand smoke exposure among Japanese adolescents from 2008 to 2017 and to examine the association between its frequency and smoking during the study period.
DESIGN, SETTING, AND PARTICIPANTS: This study comprised a nationally representative, self-administered, school-based, cross-sectional survey focusing on tobacco and alcohol use and related factors among students in grades 7 to 12 (ages 12-18 years) in Japan. This random sampling survey used single-stage cluster sampling. Using the national school directory, junior and senior high schools throughout Japan were randomly extracted from each regional block. All students enrolled in the sampled schools were included as participants, and school-based surveys were completed in 2008, 2012, and 2017. Data analysis was performed from January 1 to March 15, 2023.
Prevalence of secondhand smoke exposure among adolescents in Japan from 2008 to 2017 and changes in the association between secondhand smoke exposure frequency and prevalence of smoking were examined using multiple logistic regression analysis.
Data were analyzed for 95 680 adolescents in 2008 (50.7% boys), 100 050 in 2012 (51.6% boys), and 64 152 in 2017 (53.9% boys). At baseline, 42.0%, 38.5%, and 34.6% of the participants were junior high school students in 2008, 2012, and 2017, respectively. Based on the 2008 surveys, 51.0% of adolescents in grades 7 to 12 were exposed to secondhand smoke in any place (≥1 day during the past 7 days), 37.2% were exposed at home, and 36.5% were exposed in public places. In 2017, 36.3% of participants were exposed to secondhand smoke in any place, 23.8% were exposed at home, and 27.0% were exposed in public places. An association between secondhand smoke exposure frequency and prevalence of smoking was observed consistently regardless of survey year, location, or pattern of exposure (adjusted odds ratios ranged from 2.29 [95% CI, 1.81-2.91] for 1-2 days at home to 11.15 [95% CI, 8.50-14.62] for 7 days in public places). Stratified analysis by higher education intention indicated that the prevalence of smoking and secondhand smoke exposure decreased but remained higher among adolescents who did not intend to pursue higher education. The association between secondhand smoke and smoking did not differ substantially between groups.
In this cross-sectional study, the prevalence of secondhand smoke exposure among adolescents in Japan decreased but remained at high levels overall. There may not be a hazard-free threshold for smoking. Enhancing comprehensive tobacco control strategies is Japan's first step toward achieving smoke-free environments to protect youths. Implementation and verification of the effectiveness of smoke-free legislation should be considered.
二手烟是全球青少年健康的一个重要风险因素，包括在日本，日本应该重新评估烟草控制政策。
评估日本青少年从 2008 年到 2017 年期间接触二手烟的流行趋势，并研究其频率与研究期间吸烟之间的关联。
设计、设置和参与者：本研究是一项全国代表性的、自我管理的、基于学校的、横断面调查，重点关注日本 7 至 12 年级（12-18 岁）学生的烟草和酒精使用以及相关因素。这项随机抽样调查使用了单阶段聚类抽样。使用全国学校名录，从每个地区块中随机抽取初中和高中。所有被抽样学校的学生都被纳入参与者，学校层面的调查于 2008 年、2012 年和 2017 年完成。数据分析于 2023 年 1 月 1 日至 3 月 15 日进行。
使用多因素逻辑回归分析，评估了 2008 年至 2017 年日本青少年接触二手烟的流行率，以及二手烟暴露频率与吸烟流行率之间的关联变化。
对 2008 年的 95680 名青少年（50.7%为男生）、2012 年的 100050 名青少年（51.6%为男生）和 2017 年的 64152 名青少年（53.9%为男生）进行了数据分析。在基线时，2008 年、2012 年和 2017 年分别有 42.0%、38.5%和 34.6%的参与者为初中生。根据 2008 年的调查，51.0%的 7 至 12 年级青少年在任何地方（过去 7 天内至少 1 天）接触过二手烟，37.2%在家中接触，36.5%在公共场所接触。2017 年，36.3%的参与者在任何地方接触过二手烟，23.8%在家中接触，27.0%在公共场所接触。无论调查年份、地点或暴露模式如何，二手烟暴露频率与吸烟流行率之间均存在关联（调整后的优势比范围从在家中暴露 1-2 天的 2.29[95%置信区间，1.81-2.91]到在公共场所暴露 7 天的 11.15[95%置信区间，8.50-14.62]）。按高等教育意向进行的分层分析表明，吸烟和二手烟暴露的流行率在不打算接受高等教育的青少年中有所下降，但仍处于较高水平。二手烟与吸烟之间的关联在不同群体之间没有显著差异。
在这项横断面研究中，日本青少年接触二手烟的流行率有所下降，但总体仍处于较高水平。可能不存在吸烟的无危险阈值。日本迈向实现无烟环境以保护青少年的第一步是加强综合烟草控制策略。应考虑实施和验证无烟立法的有效性。
