Potential impacts of spatial restrictions on tobacco retail availability in China: a simulation study in Shanghai

Regulating tobacco retail availability provides promising new opportunities for effective tobacco control. This study simulates the potential impacts of introducing spatial restrictions on the availability of tobacco in Shanghai, the largest city in China.Twelve stakeholder-informed simulation scenarios under four types of spatial restrictions were considered: (1) capping, (2) ban of sales, (3) minimum spacing and (4) school-buffer exclusion zone. Tobacco retailer data for Shanghai (n=19 413) were used. The main outcome was per cent reduction in retail availability measured by population-weighted kernel density estimation across neighbourhoods, and impacts on social inequality in availability were estimated using the Kruskal-Wallis test and effect size estimation. All analyses were further stratified by three levels of urbanity to examine geographical disparities in overall effectiveness and equity of the simulation scenarios.All simulation scenarios have the potential to reduce availability, with overall reductions ranging from 8.60% to 85.45%. Compared with the baseline, the effect size regarding the association between availability and neighbourhood deprivation quintiles suggests that the most effective scenario, '500 m minimum spacing' between retailers, increased the social inequality in availability (p<0.001). Conversely, school-buffer scenarios were both effective and equitable. Additionally, the effectiveness and the equity impact of scenarios varied by urbanity level.Spatial restrictions offer potential new policy opportunities to reduce retail availability, but some may increase social inequality in accessing tobacco. For effective tobacco control, policymakers should consider the overall and equity impacts of spatial restrictions when developing comprehensive tobacco retail regulations.