Explaining Mechanisms That Influence Smoke-Free Implementation at the Local Level: A Realist Review of Smoking Bans

Introduction: While studies have been undertaken to understand the adoption of outdoor and indoor smoking bans, not much is known about why implementation of smoke-free (SF) environments differs at local levels. As most European countries remain at the level of indoor bans, we aim to translate existing evidence into practical recommendations on how to improve SF (outdoor) implementation within European municipalities. Methods: We applied six methodological steps of a realist review consistent with the RAMESES publication standards for realist syntheses. Literature search was conducted in PubMed/MEDLINE and Web of Science. In total, 3829 references were screened, of which 43 were synthesized. Studies dating from 2004 to 2015 with rigor evidence of SF implementation at the local level were selected. Implementation outcomes were SF enforcement, monitoring, nonsmoking compliance, and public support in cities. Results: The explanatory realist framework links four innovation stages with three context-mechanism-outcome (CMO)configurations. We identified "triggering trust," "increasing priorities," and "limiting opposing interests" as underlying mechanisms, when (1) establishing, (2) developing, (3) contesting, and (4) implementing local smoking bans. The CMO propositions (CMOs) support practical recommendations, such as (1) providing authorities with local data when establishing and developing bans, (2) developing long-term strategies and implementing state-funded SF programs to prioritize sustained enforcement, and (3) limiting opposing interests through the use of the child protection frame. Conclusions: This is the first realist review on the implementation of SF enviroments at the local level. The process-oriented theory explains how and why CMOs determine SF development in cities and municipalities from planning until implementation. Implications: In 2015, only 16% of the world's population lived under the jurisdiction of comprehensive SF laws. The findings of this realist review are useful to implement WHO goals of the Framework Convention on Tobacco Control (FCTC) and specifically SF environments at more local levels and to adjust them to specific contextual circumstances. This paper unpacks three mechanisms that could be triggered by SF strategies developed at local levels and that can result in improved policy implementation. Such evidence is needed to enhance SF strategies at the level of cities and municipalities and to achieve WHO "Healthy Cities Network" objectives.