Public support for smoke-free policies in outdoor areas and (semi-)private places: a systematic review and meta-analysis.

Background: Smoke-free policies are essential to protect people against tobacco smoke exposure. To successfully implement smoke-free policies that go beyond enclosed public places and workplaces, public support is important. We undertook a comprehensive systematic review of levels and determinants of public support for indoor (semi-)private and outdoor smoke-free policies. Methods: In this systematic review and meta-analysis, six electronic databases were searched for studies (published between 1 January 2004 and 19 January 2022) reporting support for (semi-)private and outdoor smoke-free policies in representative samples of at least 400 respondents aged 16 years and above. Two reviewers independently extracted data and assessed risk of bias of individual reports using the Mixed Methods Appraisal Tool. The primary outcome was proportion support for smoke-free policies, grouped according to location covered. Three-level meta-analyses, subgroup analyses and meta-regression were performed. Findings: 14,749 records were screened, of which 107 were included; 42 had low risk of bias and 65 were at moderate risk. 99 studies were included in the meta-analyses, reporting 326 measures of support from 896,016 individuals across 33 different countries. Support was pooled for indoor private areas (e.g., private cars, homes: 73%, 95% confidence interval (CI): 66-79), indoor semi-private areas (e.g., multi-unit housing: 70%, 95% CI: 48-86), outdoor hospitality areas (e.g., café and restaurant terraces: 50%, 95% CI: 43-56), outdoor non-hospitality areas (e.g., school grounds, playgrounds, parks, beaches: 69%, 95% CI: 64-73), outdoor semi-private areas (e.g., shared gardens: 67%, 95% CI: 53-79) and outdoor private areas (e.g., private balconies: 41%, 95% CI: 18-69). Subcategories showed highest support for smoke-free cars with children (86%, 95% CI: 81-89), playgrounds (80%, 95% CI: 74-86) and school grounds (76%, 95% CI: 69-83). Non-smokers and ex-smokers were more in favour of smoke-free policies compared to smokers. Support generally increased over time, and following implementation of each smoke-free policy. Interpretation: Our findings suggested that public support for novel smoke-free policies is high, especially in places frequented by children. Governments should be reassured about public support for implementation of novel smoke-free policies. Funding: Dutch Heart Foundation, Lung Foundation Netherlands, Dutch Cancer Society, Dutch Diabetes Research Foundation and Netherlands Thrombosis Foundation.