The Impacts of Green Space Structure on Asthma in Toronto, Canada

Abstract

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.

Keywords

• green space structure
• impacts
• asthma
• air pollution
• tree diversity
• Toronto