Smoke-free homes and youth smoking behavior in Italy: Findings from the SIDRIAT longitudinal study

Introduction: Few studies have explored whether smoke-free homes (SFH) can promote reductions of smoking onset in children, particularly in households with smoking parents. The aim of this study was to determine whether youths living in SFH were less likely to progress to smoking. Methods: We conducted a longitudinal, 11-year, two-wave study on 778 children aged 6-7 years and 985 adolescents aged 13-14 in 2002. At baseline, youths were asked whether or not adults smoked at home (SFH); at follow-up, in 2012-2014, whether a household smoking ban (HSB) had been implemented during the course of the study. Logistic regression was used to investigate SFH effects on youth smoking behaviors. Results: Sixty-nine percent of children and 54% of adolescents reported SFH at baseline; 80% of children and 71% of adolescents reported HSB at follow-up. Youths living in non-SFH at baseline were twice as likely to become established smokers at follow-up compared with those living in SFH (children + adolescents: odds ratio [OR] = 1.99; 95% confidence interval [CI] = 1.39-2.94; adolescents: OR = 2.15; 95% CI = 1.36-3.42; children: OR = 1.69; 95% CI = 0.80-3.56), either for youths living with nonsmoking parents at baseline and follow-up (OR for both children and adolescents = 3.06; 95% CI = 1.70-5.51) or for youths with ≥1 smoking parent at baseline and follow-up (OR = 2.12, 95% CI = 1.01-4.46). The effect was greater in youths living in the worst situation (non-SFH at baseline + non-HSB at follow-up) compared with those in the best situation (SFH at baseline + HSB at follow-up; children: OR = 3.20; 95% CI = 1.10-9.35; adolescents: OR = 5.41; 95% CI = 2.66-10.97). Conclusions: Household smoke-free policies had a significant impact in protecting youths from becoming established smokers. Implications: The results of the SIDRIAT longitudinal study showed that youths living in homes where people smoked at baseline were twice as likely to become established smokers 11 years later at follow-up, compared with youths living in SFH. The lower number of established smokers among youths living in SFH at baseline was recorded not only in households with nonsmoking parents but also in those with smoking parents. Implementing a home smoking ban is recommended in all households. Living in homes with no ban may be a risk factor for smoking initiation, which is independent of having smoking parents.