Different types of environment stimuli (e.g. noise, aesthetics) in urban environments are becoming better understood as determinants of the mental health of urban dwellers. Research on the impacts of urban exposures, especially those related to urban designs, and their potential impacts on the mental health of adolescents specifically, however, is currently lacking. In this study, we examine the relationships between five pedestrian- and transit-oriented design (PTOD) concepts - imageability, enclosure, human scale, transparency and complexity - and adolescent emotional responses to six settings of varied PTOD quality, and discuss potential design-related emotional affordances within Gibson's Theory of Affordances (ToA). Using an online survey method with videos of each setting, a nationally representative sample of Canadian adolescents viewed the videos and indicated responses to six mental health indicators (positive affect, negative affect, calmness, anxiousness, perceived restorativeness and mental demand). Adjusted linear mixed models (LMMs) were constructed to examine the association between different urban settings and each outcome. Results indicated that, generally, as the quality of five PTOD concepts increased, as reflected in the scores of the different settings, positive emotional responses tended to increase while negative responses decreased (excluding mental demand). Within the frame of the ToA, multiple emotional response outcomes were significantly associated with settings high in aggregate PTOD quality (e.g. Plaza-Positive Affect: beta = 0.116, 95% CI: 0.010-0.222, p = 0.033; Bluespace-Mental Demand: beta = -1.634, 95% CI: -1.770 to -1.498, p = <0.000), suggesting such spaces may be perceived by adolescents as possessing greater emotional richness with respect to affordances. Future studies should further explore these relationships with other means (e.g. objective methods).
