Urban Greenness and Urban Residents’ Health: A Novel Method to Assess Street Greenery

Description

Due to rapid global urbanization in recent decades, people have less and less contact with the natural environment. Research has shown that exposure to urban greenness, such as parks and tree-lined streets, is associated with health and well-being benefits (e.g. improvements to general health and mental health, the reduced prevalence of obesity, and lower mortality rates). For many governments, the creation and improvement of urban greenness are therefore essential components of an environmental strategy to improve public health. Nevertheless, there are three major research gaps. First, previous studies have almost exclusively focused on parks rather than street greenery, even though street greenery is relatively easy to improve. In addition, few studies have assessed the quality of street greenery. Therefore, little is known about the effects of street greenery on residents’ health. Second, most evidence comes from cross-sectional research, which has been rightly criticized for its inability to infer causality. This limitation makes the impacts of urban greenness on health uncertain. Third, few studies have simultaneously investigated the four potential mediating pathways (i.e. promoting physical activity, fostering social contact, reducing stress, and improving the ambient environment) underlying the effects of urban greenery on health outcomes. To address these research gaps, we will: 1) develop and validate a new method for assessing the quantity and quality of eye-level street greenery using Google Street View (GSV) images and other streetscape photos; 2) obtain evidence of the impacts of street greenery on health outcomes from a cross-sectional study (with 1,080 participants) and a natural experimental study (with 480 participants); 3) simultaneously investigate all potential mediating pathways.  The cross-sectional study will provide correlational evidence, while the natural experiment will provide evidence for establishing causal relationships. Although both cross-sectional and natural experimental studies have limitations, if the two approaches provide converging evidence, the findings regarding the effects of urban greenery on health outcomes will be more robust. The proposed project will be significant for several reasons. First, the findings will help us understand whether street greenery has a positive impact on people’s health outcomes. Second, methodologically, using GSV images will be a cost-effective way of assessing eye-level street greenery, which may stimulate further health studies. Third, the results of this study will help governments optimize their environmental policies for street greening improvement projects. Therefore, this work will improve the health and quality of life of Hong Kong residents, thereby reducing the potential healthcare costs for society.