A paper published last year by Wolf et al. attempts to quantify the economic value associated with various psychosocial, cognitive, and physical health and well-being benefits derived from US metro nature areas. Metro nature is a broadly-defined term that includes open spaces, riparian areas, parks, community gardens, streetscapes, green rooftops, and other such areas. The authors focus on 6 out of 15 such benefits documented in the peer-reviewed literature – birth weight, attention deficit hyperactivity disorder (ADHD), secondary school performance, crime, cardiovascular disease, and Alzheimer’s disease – and estimate that the annual economic value (in the form of lower and avoided costs and higher income) associated with these six health and well-being benefits totals between $2.7 and $6.8 billion (2012 $).
The health and well-being benefits are most often associated with direct and active human interaction with metro nature. As an example, interactions with nature and green areas have been found to reduce the severity of ADHD symptoms. Similarly, research indicates that a 20-minute walk in a city park can have an effect similar to that of the most common ADHD medication (methylphenidate). In contrast, at least some health and well-being benefits are not dependent upon direct active interaction with metro nature. For example, a Michigan study found that high schools with views of trees and shrubbery from their cafeteria and classroom windows have higher standardized test scores, higher graduation rates, and a greater number of students planning to attend college. Another study found that college students whose dorm rooms have natural views perform better on a variety of attention measures than do those with views of built areas. For other health and well-being benefits, it is not so clear whether direct and active interaction with metro nature is necessary. For example, studies have shown that babies born to mothers whose homes are in closer proximity to open space and more tree canopy have decreased risk of low birth weight and small gestational age.
Although I think people commonly recognize that metro nature has positive value, I don’t know that either the general populace or individuals who influence the provision of metro nature (such as city planners and other government officials) have knowledge of the breadth of the health and well-being impacts of such areas, the fact that impacts have been researched and documented, or the magnitude of the associated economic value. It seems that the provision of metro nature is a relatively easy and affordable way to influence and mitigate a number of issues that are of concern to city planners, school officials, parents, and the general public. Perhaps the provision of metro nature can kill several birds with one stone, so to speak, and provide improvements in several areas at relatively low cost.
 Wolf, K.L., Measells, M.K., Grado, S.C., and Robbins, A.S.T. 2015. Economic values of metro nature health benefits: A life course approach. Urban Forestry & Urban Greening 14, 694-701.
 Faber Taylor, A., Kuo, F., and Sullivan, W.C. 2001. Coping with ADD: The surprising connection to green play setting. Environment and Behavior 33, 54-77. Faber Taylor, A. and Kuo, F. 2009. Children with attention deficits concentrate better after walk in the park. Journal of Attention Disorders 12, 402-409. Faber Taylor, A. and Kuo, F. 2011. Could exposure to everyday green spaces help treat ADHD? Evidence from children’s play setting. Applied Psychology: Health and Well-Being 3, 281-303.
 Matsuoka, R. 2010. Student performance and high school landscapes: Examining the links. Landscape and Urban Planning 97, 273-282.
 Tennessen, C.M. and Cimprich, B. 1995. Views to nature: Effects on attention. Journal of Environmental Psychology 15, 77-85.
 Donovan, G.H., Michael, Y.L., Butry, D.T., Sullivan, A.D., and Chase, J.M. 2011. Urban trees and the risk of poor birth outcomes. Health Place 17, 390-393.