Impact of public smoking bans on social inequalities in children's exposure to tobacco smoke at home: an equity-focused systematic review.

Introduction: A systematic review was conducted to evaluate the impact of public smoking bans on social inequalities in children's secondhand smoke (SHS) exposure at home.

Methods: Five databases were electronically searched for articles on children's SHS exposure at home related to public smoking bans. Additionally, grey literature and German public health journals were considered. Search was restricted to English and German publications. Of 3037 records screened, 25 studies fulfilled the inclusion criteria by either measuring SHS exposure before and after public smoking ban introduction or by comparing exposure between regions with and without smoke-free legislation. Studies were further examined whether they additionally reported on impacts on social inequalities in SHS exposure. Information on children's SHS exposure at home in relation to smoke-free legislation were extracted by one reviewer and checked for accuracy by a second reviewer. According to PRISMA-E guidelines for equity-focused systematic reviews, the PROGRESS-Plus framework was applied to data extraction and analysis with focus on social inequalities in SHS exposure. Results were visualised by a Harvest Plot.

Results: Eight studies gave results on the impact of public smoking bans on social inequalities in children's SHS exposure. Whereas only one study indicated widening of the social gap in exposure, seven studies showed no impact or a reduction of social inequalities in exposure.

Conclusions: First evidence on short-term impact of public smoking bans does not support the assumption of intervention-generated inequalities in children's SHS exposure at home. Future studies should focus on long-term equity impacts of smoke-free legislation.

Implications: There are substantial social inequalities in children's secondhand smoke (SHS) exposure in many countries. Both hypotheses on the effect of smoke-free legislation on children's SHS exposure at home, the displacement hypothesis and the social diffusion hypothesis, did not take social inequalities into account. Up to now, only few studies analysed the effects of smoke-free legislation on social inequalities in children's SHS exposure at home. Public smoking bans had overall no negative impact on social inequalities in children's SHS exposure at home. More consistent reporting of absolute and relative inequalities is needed to comprehensively assess equity impact of smoke-free legislation.