Assessing the Associations between Environmental Exposures, Mobility, and Anxiety Symptoms

Mental health disorders, including anxiety, are among the leading causes of disability worldwide. Numerous studies have linked air pollution and noise to adverse mental health outcomes, whereas exposure to green and blue spaces tends to have beneficial associations. However, much of the existing research relies on static, residence-based exposure assessments, overlooking the fact that people often spend a significant portion of their day outside their residential environments and experience varying environmental conditions throughout the day. Moreover, few studies have distinguished between different exposure metrics, which may capture distinct aspects of environmental exposure and their potential links to mental health. This thesis aimed to advance the understanding of the associations between diverse environmental exposures, mobility behaviours, and anxiety symptoms by incorporating multiple exposure metrics and accounting for their spatial and temporal dynamics. Using survey and smartphone-based tracking data from the NEEDS project, five empirical studies were conducted. First, a systematic review and meta-analysis indicated a suggestive positive association between traffic noise and anxiety symptoms, which reached significance for severe anxiety symptoms. However, results varied across specific noise sources. Second, pathways linking the availability and visitation of nature to mental health were explored; nature availability was only indirectly linked to depression symptoms, via mediators such as the frequency of visits, physical activity, social contact, and stress reduction, while associations with anxiety symptoms were largely insignificant. Third, we analysed the associations between anxiety symptoms and mobility and social behaviour, revealing that visiting more locations on weekends was associated with fewer anxiety symptoms, whereas other behavioural features showed no significant associations. Fourth, nonlinear relationships were identified between anxiety symptoms and mobility-based environmental exposures. A negative association with green space exposure was observed among participants with moderate exposure levels, while positive associations were found for high levels of noise and air pollution. Finally, daily sequential exposure patterns were characterized and four distinct daily sequential exposure patterns were identified. Participants with “moderately health-threatening” daily exposure sequences reported fewer anxiety symptoms than those with “strongly health-threatening” patterns. Overall, this research demonstrates the value of integrating spatiotemporal exposure dynamics, differentiating exposure types, and considering active engagement with natural environments when examining environmental determinants of anxiety symptoms. The findings provide nuanced insights to inform public health interventions and urban planning strategies aimed at promoting mental well-being.