Examining the scale effect of nearby residential green space on residents' BMI: A case study of Guangzhou, China

Green spaces are closely related to the quality of the urban environment and public health. However, studies have rarely paid attention to nearby residential green space which is more closely connected to residents' daily lives. Does nearby residential green space have a scale effect on the body mass index (BMI) of residents? What type of green space has a more significant effect? Does this effect differ for residents living in central urban areas and suburban areas? To answer these questions, this study first measured three scales of nearby residential green space accessibility of 1398 samples of 18 neighborhoods' survey data in Guangzhou, China, combined with the application of the TIQS (Travel O-D point Intelligent Query System). And then, multilevel mixed-effects models were developed to examine the scale effect of nearby residential green space accessibility on residents' BMI. The results show that nearby residential green space has a scale effect on individual BMI and the effect of the 10-minute walking scale is the most significant. Within a 10-minute walking distance from the residence, the larger the green space and the more accessible it is, the lower the individual's BMI. Parks are the green spaces that are most correlated to residents' BMI, but their effect is somewhat different between the central urban areas and suburban areas. These findings give us a better understanding of the association between nearby residential green space and public health, as well as providing implications for the improvement of the urban green space system and policy development for healthy cities.