[Effects of ordinances prohibiting smoking in private homes with children following smoke-free household rules in Tokyo].

Abstract

Objectives\u3000Exposure to secondhand smoke is harmful to children s health. Therefore, the Tokyo metropolitan area implemented an ordinance on April 1st, 2018 that prohibits smoking in private homes when children are present. To date, the effect of this ordinance has not been studied. In this study, we evaluated the change in the percentage of residents in the Tokyo metropolitan area who have smoke-free household rules using difference-in-difference (DID) analysis.Methods\u3000A one year, follow-up, longitudinal internet survey of the general Japanese population was conducted from 2018 to 2019 (Japan Society and New Tobacco Internet Survey, JASTIS). DID analysis was conducted using the percentage of residents who have smoke-free household rules in Tokyo metropolitan area and control groups in 2018 and 2019.Results\u3000We utilized three control groups (Control 1: residents in Japan except from Tokyo metropolitan area; Control 2: residents in Japan except from Kanto region; Control 3: residents in prefectures which have ordinance-designated city) for DID analysis. Covariate-adjusted DID estimates for each control group were -1.0 percentage points (Control 1, 95% Confidence Interval (CI)=-5.8, 3.9), -1.0 percentage points (Control 2, 95% CI=-5.9, 4.0), and -1.0 percentage points (Control 3, 95% CI=-5.9, 3.9) indicating that there was no significant difference for all control groups. Moreover, no significant difference was observed when respondents answers were analyzed and stratified according to sex, age, household income, housing tenure, smoking status, education, or marital status.Conclusions\u3000DID analysis revealed no significant change in the percentage of residents of the Tokyo metropolitan area who have smoke-free household rules after the implementation of the ordinance. This study will be useful for local governments when planning and promoting more effective smoke-free ordinances.