Can biodiverse streetscapes mitigate the effects of noise and air pollution on human wellbeing?

Changes to the behaviours and priorities of the human population have led to an unprecedented number of urban inhabitants worldwide. Urban dwellers are exposed to high levels of air and noise pollution that negatively impact both human well-being and species diversity. However, research has shown that

biodiversity present within urban areas can positively contribute toward human well-being. Despite this, no literature to date has examined the potential for urban biodiversity to mitigate or lessen the negative associations between air and noise pollution and mental well-being. This study used parallel mediation

models to examine the complex interplay between these factors, testing whether species richness (actual and perceived) can mediate the relationship between air (PM2.5) and noise (dB) pollution and well-being (mental well-being and happiness) across 30 streetscapes in the city of Leeds, UK. The results revealed

that greater actual flowering plant richness reduced the negative impact of noise pollution on resident's self-reported well-being across streetscapes. Additionally, there was a direct negative association between noise pollution and flowering plant and pollinator richness. This could be because residents

are deterred from gardening in streetscapes where noise pollution is high. However, noise pollution can also have a direct negative impact on pollinator species. No direct or mediated negative associations between air pollution and well-being measures were identified in this study. This thesis provides a

valuable insight into the complex interplay between streetscape pollution, biodiversity and human mental well-being, which until now remained largely unexamined. Increasing plant diversity should be considered a priority within any future plans to reduce urban noise. In turn, critical gains in pollinator

conservation can also be made. Trends in population growth, increased pollution and declines in mental health that characterise cities worldwide, mean that the findings presented here are applicable to a multitude of urban settings.