Measuring the health effects of 'Green' and 'blue' elements in different types of urban environments by employing wearable sensors: A field experiment in Copenhagen, Denmark

Urban green and blue spaces not only provide environmental benefits to the quality of city life, but also generate positive health effects for people living in cities. Recent studies advocate for the need to evaluate the therapeutic value of urban green and blue spaces. To achieve this goal, this study aims to measure how human respond to urban “green” and “blue” elements in different kinds of urban environment. We conducted a field experiment in Copenhagen municipality from June to September 2021.The experiment entailed using FrontRow wearable lifestyle camera, GPS tracker and Empatica 4 wristband as a sensor package to capture personal urban exposures and localised personal physiological responses to the urban environments. In this field experiment, volunteers (k=85) wore three sensors and walked through six urban sites (waterfront area/transit area/greenery area /commercial area/traffic area/residential area). On each site, the volunteers had a 5-minute rest followed by a 15-minute self-leading walk. In the end, our experiment collected images representing personal exposures to urban elements and the corresponding physiological responses. Focusing on the exposures to “Green” and “Blue” features, we took advantage of Microsoft API of cognitive service to detect the existence of urban “green” (e.g., tree/grass/flower/garden/bush) and urban “blue” (e.g., water/lake/fountain) in the collected images. Further, we analysed the spatial relationship between the distributions of “Green/Blue” features and human’s body responses in the six sites. Our findings indicate that the existence of “Green” and “blue” elements can effectively decrease the stress perceived from the surroundings. The study provides novel insights to investigating human health in different urban environments and highlights the value of green and blue spaces in promoting good health.