Casual evaluation of the effects of a large-scale greenway intervention on physical and mental health: A natural experimental study in China

Many cross-sectional studies have supported the health benefits of urban greenways. However, the causal relationship between urban greenway intervention and residents’ physical and mental health remains unclear. Furthermore, the potential dose-response effect by distance to a greenway intervention remains unknown. This study explored the impact of a large-scale urban greenway intervention (construction of a 102-km-long East Lake Greenway in Wuhan, China) on the health outcomes of residents by using a natural experimental research design. We collected data before and after the intervention (in 2016 and 2019, respectively) from 1,020 participants living within a 5-km street-network distance from the entrances of this greenway. The average age of the participants was approximately 50, and most of them were married. More than half of the participants were female, currently employed, and had received a college education or above. Mixed-effects difference-in-difference (DID) models were used while controlling for individual and neighbourhood covariates. The results showed that the East Lake Greenway had a positive effect on the self-reported mental health of residents who lived within 2 km, and these benefits decreased with distance. The physical health benefit was insignificant. To increase the health benefits of urban greenways, more effort should be made to improve the accessibility of greenways and the surrounding environment. We also advocate that future natural experiments should explore the distance-varying dose-response effect of green space interventions on health outcomes.