Yuping Dong

Asthma is a chronic inflammatory disease that can be caused by various factors, such as asthma-related genes, lifestyle, and air pollution, and it can result in adverse impacts on asthmatics’ mental health and quality of life. Hence, asthma issues have been widely studied, mainly from demographic, socioeconomic, and genetic perspectives. Although it is becoming increasingly clear that asthma is likely influenced by green spaces, the underlying mechanisms are still unclear and inconsistent. Moreover, green space influences the prevalence of asthma concurrently in multiple ways, but most existing studies have explored only one pathway or a partial pathway, rather than the multi-pathways. Compared to greenness (measured by Normalized Difference Vegetation Index, tree density, etc.), green space structure—which has the potential to impact the concentration of air pollution and microbial diversity—is still less investigated in studies on the influence of green space on asthma. Given this research gap, this research took Toronto, Canada, as a case study to explore the two pathways between green space structure and the prevalence of asthma based on controlling the related covariates. Using regression analysis, it was found that green space structure can protect those aged 0–19 years from a high risk of developing asthma, and this direct protective effect can be enhanced by high tree diversity. For adults, green space structure does not influence the prevalence of asthma unless moderated by tree diversity (a measurement of the richness and diversity of trees). However, this impact was not found in adult females. Moreover, the hypothesis that green space structure influences the prevalence of asthma by reducing air pollution was not confirmed in this study, which can be attributed to a variety of causes.

A series of studies have proved that green space can influence air pollution, which is the main risk factor for asthma. In addition, the biodiversity hypothesis suggests use of green space can contribute to increasing human commensal microbiota on the skin, which makes it possible to enhance immunity to allergic atopy. Given that, the co-effects of green space might jointly influence asthma. However, existing studies mainly focus on one or part of the pathway between them, and most of them shed light on the influence of greenness or trees on asthma. Green space structure, capable to influence both air pollution and microbial diversity, is also probably a significant factor to influence asthma. Regarding this, this study takes Toronto as the case to explore two potential mechanisms that shape the impact of green space structure on asthma. Additionally, tree diversity that might moderate this impact was also examined in this study. By regression analysis, it is found that the impact of green space structure on the prevalence of asthma by reducing air pollution was not evident. Moreover, green space structure has no significant contribution to the prevalence of asthma, but when moderated by tree diversity, it has the potential to reduce the prevalence of male asthmatics, and such moderation effect only works on male asthmatics. Except for that, several covariates selected in this study were also found to correlate with the prevalence of asthma. In particular, the relationship between household income and the prevalence of asthma is only significant among female asthmatics.

A high greenness level can enhance green space use and outdoor physical activity. However, rapid urbanization and high-density development have led to the loss or fragmentation of green space, especially urban public green space (PGS). With the aim of increasing the health benefits from PGS, some planners and researchers suggest connecting existing PGSs to encourage urban residents to use the PGS, and thus, to improve public health. Does this suggestion stand with robustness? By taking 42 sub-districts in the inner area of Wuhan as the study objects, this paper examines the correlation between the connectivity of PGS and its use. We also explore how the characteristics of PGS and the facilities/functions in the neighboring areas influence this relationship by using Location Based Service data (WeChat-Yichuxing data), point of interest (POI) data, and remote-sensing image, etc. Using Regression Analysis, we found that there is no high correlation between PGS use and its connectivity. The possible causes might be attributed to the fact that PGS use is profoundly influenced by multifaceted competing impact factors, and no one can stand dominantly. It is interesting to see that the density of companies is positively, but slightly, related to PGS use.

Research has proved that urban green space can be utilized to promote public health. While exploring the underlying mechanism, the main focus is always on the meso-scale characteristics of urban green space such as accessibility, availability, proximity, and its micro-scale attributes like area, quantity, constituent elements and environmental perception. Yet, its spatial distribution, as the macro-scale characteristics of urban green space, is also closely related to residents’ health but has not well been explored. Regarding this, this paper takes the inner-city area of Wuhan as an example to evaluate the spatial distribution of the green space with Jiedao as the basic analysis unit. By buffer analysis and zonal analysis, the evaluation is conducted from five dimensions which are balance, equality, availability, accessibility and quality. The results show that, except in balance, the distribution of health-promotion green space is not satisfactory in the other four dimensions, especially in accessibility, quality and equality. The underlying causes could be attributed to three aspects of the current urban green space planning: (1) emphasis on ecology-oriented value and the application of “top-down” planning approach; (2) adoption of a single-dimension index system; (3) application of a static but not an adaptive framework. Therefore, from planning perspective, to shift the value-orientation and readjust the framework of urban green space planning will be one key solution to the identified problems.