Long-term follow-up of the public health impacts and co-benefits of an urban greenway intervention: A 15-year natural experiment evaluation

BackgroundEvidence on the long-term impact of urban green and blue spaces (UGBS) interventions remains limited. This study is a 15-year evaluation of an urban greenway development in Belfast (United Kingdom), assessing the potential effects of this UGBS intervention on physical activity (PA), mental wellbeing and co-benefits. MethodsUsing quasi-experimental design, a repeated cross-sectional survey was conducted in 2010 (baseline), 2017 (post-opening) and 2023 (long-term follow-up) with about 1,200 adults participated each wave. Outcomes included PA, mental wellbeing, general health, quality of life, social capital and environmental perception. Multilevel mixed-effect regressions were performed to examine within-group changes at long-term follow-up. Difference-in-differences analysis investigated the between-group changes that might be attributed to the greenway. Additional comparative analyses included distance-decay analysis and comparison with population trends in Northern Ireland. ResultsAt six years after completion, the greenway intervention appears to buffer a decline in duration of PA - mainly from moderate-intensity activity (decline lower by 118.6 min/week, 95%CI: 3.9-232.2) but with no significant impact on the proportion of the population meeting the recommended PA level. The intervention is associated with a smaller decline in self-rated health (4.98 units; 95%CI: 0.62-9.34) relative to control group. Intervention association with mental wellbeing was positive but not significant (p=0.30). The greenway also showed positive effects on social capital and environmental perceptions, with impacts most evident in improving safety and trust in the local area. ConclusionThis study provides evidence to support the public health impact of UGBS and its long-term health and social benefits.