Does urban blue-green space rejuvenate residents' mental well-being in megacity? An empirical analysis of Dhaka, Bangladesh

The significance of urban blue-green spaces (UBGS) in improving mental well-being (MWB) has attracted increasing academic attention, yet evidence from densely populated and rapidly urbanizing low-income countries remains limited. This study explores the association between UBGS and MWB in Dhaka, Bangladesh, by controlling individual and built environmental factors. Multilevel Structural Equation Modeling (MSEM) is used to assess how UBGS and the urban built environment (UBE) influence MWB, while accounting for site-level differences and the mediating roles of social cohesion and physical activity. MWB had a direct positive effect with UBGS proximity, showing the most substantial impact for residents living within a 301–500 m buffer of the nearest UBGS (β = 0.154***). Features of UBGS (accessibility, landscaping, safety, and functional amenities) enhance MWB through social cohesion, and physical activity. UBGS enhanced MWB through social cohesion and physical activity, with combined indirect effects of (β = 0.25**) at the individual level and (β = 0.37**) at the neighborhood level. The model showed good fitness, with RMSEA = 0.041, CFI = 0.966, and ICC values ranging from 0.34 to 0.52 indicating substantial between-group variation. Luxurious neighborhoods, connected blue spaces, educated residents, and higher income (≈$442.49+) showed stronger positive coefficients with MWB. Rapidly urbanizing cities should preserve and create new UBGS to meet the growing demand for healthy living conditions, maintain environmental quality amidst dense population and unplanned growth.