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Accumulating evidence indicates that simulated natural settings can engage mechanisms that promote health. Simulations offer alternatives to actual natural settings for populations unable to travel outdoors safely; however, few studies have contrasted the effects of simulations of natural settings to their actual outdoor counterparts. We compared the impacts of simulated and actual natural settings on positive and negative affect (mood) levels using a pooled sample of participants enrolled in extant experimental studies. Relevant articles were identified from a review of research published/in press by March 2020 and updated during the peer review of the current study. Of 16 articles identified, 6 met the inclusion criteria and administered a single cross-cutting, standardized instrument [the Positive and Negative Affect Schedule (PANAS)] before and after exposure. Random effects meta-analysis of pooled effects showed that positive affect increased in the actual settings but not in their simulated counterparts (Hedge's g = 0.87; 95% CI, 0.54, 1.20). We observed little difference in effects on negative affect change scores (g = −0.28; 95% CI, −0.62, 0.06), with studies generally showing reductions in negative affect in both settings. Further research with additional populations, settings, antecedent conditions, and durations would provide a more robust understanding of differences in effects between these two ways to enhance mood by viewing nature. [ABSTRACT FROM AUTHOR]

Background Urban greenspace can benefit mental health through multiple mechanisms. They may work together, but previous studies have treated them as independent. Objectives We aimed to compare single and parallel mediation models, which estimate the independent contributions of different paths, to several models that posit serial mediation components in the pathway from greenspace to mental health. Methods We collected cross-sectional survey data from 399 participants (15–25 years of age) in the city of Plovdiv, Bulgaria. Objective “exposure” to urban residential greenspace was defined by the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index, tree cover density within the 500-m buffer, and Euclidean distance to the nearest urban greenspace. Self-reported measures of availability, access, quality, and usage of greenspace were also used. Mental health was measured with the General Health Questionnaire. The following potential mediators were considered in single and parallel mediation models: restorative quality of the neighborhood, neighborhood social cohesion, commuting and leisure time physical activity, road traffic noise annoyance, and perceived air pollution. Four models were tested with the following serial mediation components: (1) restorative quality → social cohesion; (2) restorative quality → physical activity; (3) perceived traffic pollution → restorative quality; (4) and noise annoyance → physical activity. Results There was no direct association between objectively-measured greenspace and mental health. For the 500-m buffer, the tests of the single mediator models suggested that restorative quality mediated the relationship between NDVI and mental health. Tests of parallel mediation models did not find any significant indirect effects. In line with theory, tests of the serial mediation models showed that higher restorative quality was associated with more physical activity and more social cohesion, and in turn with better mental health. As for self-reported greenspace measures, single mediation through restorative quality was significant only for time in greenspace, and there was no mediation though restorative quality in the parallel mediation models; however, serial mediation through restorative quality and social cohesion/physical activity was indicated for all self-reported measures except for greenspace quality. Conclusions Statistical models should adequately address the theoretically indicated interdependencies between mechanisms underlying association between greenspace and mental health. If such causal relationships hold, testing mediators alone or in parallel may lead to incorrect inferences about the relative contribution of specific paths, and thus to inappropriate intervention strategies. [ABSTRACT FROM AUTHOR]

Urbanization, resource exploitation, and lifestyle changes have diminished possibilities for human contact with nature in urbanized societies. Concern about the loss has helped motivate research on the health benefits of contact with nature. Reviewing that research here, we focus on nature as represented by aspects of the physical environment relevant to planning, design, and policy measures that serve broad segments of urbanized societies. We discuss difficulties in defining 'nature' and reasons for the current expansion of the research field, and we assess available reviews. We then consider research on pathways between nature and health involving air quality, physical activity, social cohesion, and stress reduction. Finally, we discuss methodological issues and priorities for future research. The extant research does describe an array of benefits of contact with nature, and evidence regarding some benefits is strong; however, some findings indicate caution is needed in applying beliefs about those benefits, and substantial gaps in knowledge remain. [ABSTRACT FROM AUTHOR]