Effects of blue space exposure in urban and natural environments on psychological and physiological responses: A within-subject experiment

Contact with nature results in a wide range of benefits to human health. Most previous studies have focused on the benefits of green spaces on human health, so evidence pertaining to the relationship between outdoor blue spaces and human health is scarce and inconclusive. Using a within-subject field experiment of 30-minute walks, this study investigated not only the physiological and psychological restorative effects of green space and blue space but also the distinctive effects of incorporating blue space into natural environments and urban environments. Based on the results of the generalized additive mixed-effect models in this study, green space can increase physiological relaxation and psychological restoration and reduce the feelings of fatigue and tension. Blue space demonstrated its potential health benefits; however, the results were limited to greater positive moods (feelings of esteem and vigor) and mental restoration, indicating that its power to promote health and well-being is limited compared to green space. Nevertheless, incorporating water with other environments, such as green spaces and urban environments, resulted in pronounced physiological and psychological relaxation effects. Natural environments containing water bodies were more effective in reducing sympathetic nervous activity than urban environments with blue space. Blue space can override many unpleasant features of urban settings and enhance the health-promoting capacity of urban spaces. Participants walking in urban areas containing water responded with greater positive mood improvement and reported stronger feelings of being away than participants in natural environments containing water bodies. These findings contribute to healthy landscape design by increasing awareness of the restorative value and potential of blue space.