This study investigates the momentary association between urban greenspace, captured using Normalized Difference Vegetation Index (NDVI) derived from Landsat imagery, and psychological stress, captured using Geographic Ecological Momentary Assessment (GEMA), in the activity spaces of a sample of primarily African American adolescents residing in Richmond, Virginia. We employ generalized estimating equations (GEE) to estimate the effect of exposure to urban greenspace on stress and test for moderation by sex, emotional dysregulation, season, neighborhood disadvantage, and whether the observation occurs at home or elsewhere. Results indicate that urban greenspace is associated with lower stress when subjects are away from home, which we speculate is due to the properties of stress reduction and attention restoration associated with exposure to natural areas, and to the primacy of other family dynamics mechanisms of stress within the home. Subjects may also seek out urban greenspaces at times of lower stress or explicitly for purposes of stress reduction. The greenspace-stress association away from home did not differ by sex, emotional dysregulation, neighborhood disadvantage, or season, the latter of which suggests that the observed greenspace-stress relationship is associated with being in a natural environment rather than strictly exposure to abundant green vegetation. Given the association of urban greenspace with lower stress found here and in other studies, future research should address the mediated pathways between greenspace, stress, and stress-related negative health outcomes for different population subgroups as a means toward understanding and addressing health disparities.
Psychological stress is a risk factor not only for mental disorders such as depression and anxiety, but also for a wide range of other ailments, including stroke, heart attack, and substance use disorders (Iwata, Ota, & Duman, 2013; O’Donnell et al., 2016; Rosengren et al., 2004; Sinha, 2008). Recent research indicates that exposure to vegetation and natural areas can mitigate psychological stress by providing opportunities for physical activity and social interaction, as well as by engendering cognitive and physiological responses associated with psychological stress reduction and attention restoration following stressful experiences (Bratman, Hamilton, & Daily, 2012 Hartig, Mitchell, de Vries, & Frumkin, 2014). Such effects may be particularly pronounced for those living in urban areas, where exposure to urban vegetated or natural areas, referred to as ‘urban greenspace,’ may be limited. Indeed, research indicates that city residents have a higher level of psychological stress as compared to those living in rural areas (Dhingra, Strine, Holt, Berry, & Mokdad, 2009; Lambert, Nelson, Jovanovic, & Cerdá, 2015; Verheij, Maas, & Groenewegen, 2008). This is of particular concern given both the increasing concentration of the world’s population in cities (Turner, Nakamura, & Dinetti, 2004) and inequities in exposure and access to urban greenspace (Wolch, Byrne, & Newell, 2014). Understanding the relationship between greenspace and psychological stress among urban residents is thus of utmost concern for the development of interrelated policies on urban health, environmental justice, and greenspace infrastructure (Maller, Townsend, Pryor, Brown, & St. Leger, 2006; Sullivan & Chang, 2011; WHO, 2012). Most observational studies of urban greenspace and psychological stress or other indicators of mental health, however, have been limited to measures of greenspace exposure based on the residential neighborhood, or where measures of greenspace exposure and stress are asynchronous or are derived from recall-based surveys (e.g. Feda, Seelbinder, Baek, & Raja, 2015; Maas, Verheij, Groenewegen, Vries, & Spreeuwenberg, 2006; Markevych et al., 2014).