Natural Dose of Blue Restoration: A Field Experiment on Mental Restoration of Urban Blue Spaces

Urban Blue Spaces (UBS) have been found to be beneficial to people's mental health. Yet, the empirical evidence for how and why different types of urban blue spaces could promote residents' mental health is still limited. Accordingly, 164 observation samples were collected for this experiment relating to the restorative perception of environmental exposure. The effects of two exposure behaviors (15 min of viewing and 15 min of walking) on psychological recovery in three different urban blue spaces settings (Urban River, Urban Canal, Urban Lake) were investigated in a field experiment. These are the main findings of this current study: (1) all three UBSs increased vitality, feelings of restoration, and positive emotions, and decreased negative emotions; (2) the mental restoration effects between walking and viewing among the three UBSs showed no significant differences; (3) of the three UBSs, urban rivers and urban lakes were the most restorative, while urban canals were less so; (4) the concept of "natural health dose" is proposed, where the health experiences of different UBSs in urban settings can show differences depending on the natural components and their levels of the environment (blue, blue + green, blue + blue). The results of this experiment can provide fundamental evidence that can contribute to building healthy cities through the management and design of different blue spaces.