Benefits of urban blue and green areas to the health and well-being of older adults

Urban Blue (like lakes, rivers and streams) and Green Areas (like parks or woods), UBGAs, provide natural areas within cities, potentially contributing to a better health and wellbeing (H&W) of citizens. However, if degraded these ecosystems pose a potential risk for human health. Understanding the role of UBGAs in citizens' health and wellbeing is crucial for developing sustainable cities under the One Health framework, particularly for vulnerable citizens like older adults, which hasn't been clearly demonstrated. To fill this gap and amplify existing evidence, we searched for studies published between 2011 and 2021 (WoS and PubMed). Our revision indicates that natural urban areas benefit older citizens H&W. The 174 studies selected were mostly from developed countries, addressing mainly urban green areas, like parks or forests (86%), while few were focused on urban blue areas (3%). Perceived health tends to increase in proportion and with the proximity to UBGAs. Larger UBGAs were positively associated with physical activity and negatively associated with depression. A higher Normalized Difference Vegetation Index was associated to lower mortality. Physical activity is often used a surrogate of physical health which may lead to several bias, as it doesn't distinguish the effect of degraded from health and biodiverse ecosystems on H&W. Most studies used indicators of quantity of UGBAs (e.g., size, number). Yet, it is crucial to also investigate the influence of quality aspects (i.e., ecological quality, biodiversity and conservation status), as the ecosystems health affects the supply of ecosystem services relevant for human health.