Unequal access to restorative coastal blue-green places: social vulnerability and place-based well-being opportunities in a coastal metropolis.

BACKGROUND: Urban blue-green environments are vital components of the urban exposome, shaping daily opportunities for physical activity, stress mitigation, and broader public health. However, these benefits depend on daily accessibility. In compact coastal metropolises, extensive nature may coexist with highly unequal residential access. This study investigates whether socially vulnerable residential areas in Shenzhen experience reduced exposure to public green and coastal blue spaces.

METHODS: Using 4,071 residential patches, a residential-scale exposure framework was developed. Social vulnerability was estimated with housing price, property-management fee, dwelling age, and neighborhood commercial-service structure. Blue-green exposure was calculated through a supply-demand model integrating walking-network accessibility, 15-min living-circle coverage, and residential demand. Lorenz curves evaluated capacity-weighted inequality. Scatterplots and quadrant typology analysis identified nonlinear associations and areas where high vulnerability coincided with low exposure.

RESULTS: Exposure to potentially restorative coastal blue-green places was unevenly distributed across Shenzhen. Residential areas with high or relatively high green-space exposure accounted for 16.12% of total residential area, whereas 167.31 km2, or 12.77%, was classified as low exposure. Coastal blue-space exposure was more concentrated: 95.71% of residential land fell within the lowest exposure category, while high and relatively high exposure accounted for only 0.49 and 0.70%, respectively. The lowest-exposure 80% of capacity-weighted residential locations accounted for 11.08% of total green-space exposure, and approximately 94.76% of capacity-weighted residential locations had almost no coastal blue-space exposure. High green-space exposure became rare at high social vulnerability levels, and no substantial blue-space exposure was observed among patches with SVI values above approximately 0.85.

CONCLUSION: Socially vulnerable communities endure a compounded socio-environmental disadvantage, wherein systemic socioeconomic marginalization is exacerbated by severe spatial deprivation of everyday restorative blue-green exposures. This spatial mismatch underscores that the mere physical presence of urban nature does not equate to equitable health-promoting opportunities. To advance environmental health equity, urban governance must transcend macro-level ecological expansion to prioritize targeted, neighborhood-scale interventions. By integrating micro-spatial renewal, enhancing inclusive waterfront connectivity, and implementing robust anti-displacement safeguards, healthy-city planning can ensure that the salutogenic benefits of the urban exposome are equitably accessible to all residents.