Green space is now widely viewed as a health-promoting characteristic of residential environments, and has been linked to mental health benefits such as recovery from mental fatigue and reduced stress, particularly through experimental work in environmental psychology. Few population level studies have examined the relationships between green space and mental health. Further, few studies have considered the role of green space in non-urban settings. This study contributes a population-level perspective from the United States to examine the relationship between environmental green space and mental health outcomes in a study area that includes a spectrum of urban to rural environments. Multivariate survey regression analyses examine the association between green space and mental health using the unique, population-based Survey of the Health of Wisconsin database. Analyses were adjusted for length of residence in the neighborhood to reduce the impact of neighborhood selection bias. Higher levels of neighborhood green space were associated with significantly lower levels of symptomology for depression, anxiety and stress, after controlling for a wide range of confounding factors. Results suggest that “greening” could be a potential population mental health improvement strategy in the United States.
The presence of green space, such as forests and parks, is now widely viewed as a health-promoting characteristic of residential environments, and has been linked to benefits such as recovery from mental fatigue [1,2,3,4,5,6,7], stress reduction [8,9,10] neighborhood social cohesion , reductions in crime, violence and aggression [12,13,14,15], reduced morbidity in multiple disease categories [16,17,18] and better self-reported health [17,18,19].
Some studies have demonstrated that the relationship between green space and health is stronger among lower socioeconomic status groups, the elderly, and others who stay home during the day, providing some support for the notion that the size of the effect of local green space on health is related to the amount of an individual’s exposure to the local environment [17,19]. These findings suggest that increasing neighborhood access to green space could be a cost-effective strategy to improving health and reducing health disparities, as lower socioeconomic status groups have a more limited ability to travel beyond local neighborhoods, resulting in increased dependence on local environments for healthy lifestyles and exposures [7,17,19,20,21,22,23]. Given evidence suggesting health benefits of exposure to green space and stronger effects among some racial, ethnic, or socioeconomic groups, it has been suggested that green spaces could be “systematically deployed to mitigate health inequalities” in addition to improving health overall [7,23].
However, while green space holds great promise as an innovative, place-based solution to improving population health, understanding where and for whom green space confers health benefits has proven complex. Some evidence and theoretical guidance has suggested that several main pathways may be important in linking green space exposure to health benefits. Green space can have direct protective effects against health hazards posed by air pollution, extreme temperature, and noise pollution [24,25]; has been associated with increased health promoting behaviors such as physical activity [23,26]; and linked to increased levels of social support, social cohesion, and sense of community [11,27,28,29]; and to mental health benefits s
uch as stress reduction [8,10,23]; buffering between stressors and health outcomes ; and attention restoration that reduces mental fatigue [1,2,3,4,5,6]. Recent research has linked green space directly to biomarkers of stress and attention—diurnal variation of salivary cortisol [8,10] and brain waves as measured by portable EEG devices [9,31]—suggesting a biologically plausible link between exposure to green space and reduction of stress and mental fatigue.
The mental health benefits conferred by green space are of particular interest given a growing body of knowledge that emphasizes stress responses as a main link between neighborhood conditions and health outcomes. Attention Restoration Theory posits that experiences in natural environments can reduce mental fatigue and restore the capability for directed attention. Directed attention is employed “when something (does) not of itself attract attention, but when it (is) important to attend nonetheless” . Maintaining this focus requires mental effort, which can lead to mental fatigue. In order to recover from mental fatigue, an individual must have the opportunity to relax directed attention. One way to accomplish this is to engage in another kind of attention—fascination attention—which occurs involuntarily and does not require the same mental effort as directed attention. Scholars argue that natural environments have the inherent capacity to fascinate, thereby providing a restorative experience that enables recovery from mental fatigue. This may be particularly relevant when considering the directed attention demands of fast-paced, modern, urban environments .
1Division of Epidemiology, Institute for Health and Society, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA; E-Mail: moc.liamg@0432aerd
2Division of Biostatistics, Institute for Health and Society, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA; E-Mail: ude.wcm@obazsa
3PhD Program in Public and Community Health, Institute for Health and Society, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA; E-Mail: ude.wcm@ragobs
4Department of Population Health Sciences, University of Wisconsin-Madison, Wisconsin Alumni Research Foundation, 610 Walnut St., Madison, WI 53726, USA; E-Mails: ude.csiw@oteinjf (F.J.N.); ude.csiw@ikcelamk (K.M.M.)
*Author to whom correspondence should be addressed; E-Mail: ude.wcm@reyebk;