Researchers are increasingly exploring how neighborhood greenness, or vegetation, may affect health behaviors and outcomes. Greenness may influence health by promoting physical activity and social contact; decreasing stress; and mitigating air pollution, noise, and heat exposure. Greenness is generally measured using satellite-based vegetation indices or land-use databases linked to participants’ addresses. In this review, we found fairly strong evidence for a positive association between greenness and physical activity, and a less consistent negative association between greenness and body weight. Research suggests greenness is protective against adverse mental health outcomes, cardiovascular disease, and mortality, though most studies were limited by cross-sectional or ecological design. There is consistent evidence that greenness exposure during pregnancy is positively associated with birth weight, though findings for other birth outcomes are less conclusive. Future research should follow subjects prospectively, differentiate between greenness quantity and quality, and identify mediators and effect modifiers of greenness-health associations.

Background:Green, natural environments may ameliorate adverse environmental exposures (e.g., air pollution, noise, and extreme heat), increase physical activity and social engagement, and lower stress.Objectives:We aimed to examine the prospective association between residential greenness and mortality.Methods:Using data from the U.S.-based Nurses’ Health Study prospective cohort, we defined cumulative average time-varying seasonal greenness surrounding each participant’s address using satellite imagery [Normalized Difference Vegetation Index (NDVI)]. We followed 108,630 women and observed 8,604 deaths between 2000 and 2008.Results:In models adjusted for mortality risk factors (age, race/ethnicity, smoking, and individual- and area-level socioeconomic status), women living in the highest quintile of cumulative average greenness (accounting for changes in residence during follow-up) in the 250-m area around their home had a 12% lower rate of all-cause nonaccidental mortality [95% confidence interval (CI); 0.82, 0.94] than those in the lowest quintile. The results were consistent for the 1,250-m area, although the relationship was slightly attenuated. These associations were strongest for respiratory and cancer mortality. The findings from a mediation analysis suggested that the association between greenness and mortality may be at least partly mediated by physical activity, particulate matter < 2.5 μm, social engagement, and depression.Conclusions:Higher levels of green vegetation were associated with decreased mortality. Policies to increase vegetation may provide opportunities for physical activity, reduce harmful exposures, increase social engagement, and improve mental health. Planting vegetation may mitigate the effects of climate change; in addition, evidence of an association between vegetation and lower mortality rates suggests it also might be used to improve health.Citation:James P, Hart JE, Banay RF, Laden F. 2016. Exposure to greenness and mortality in a nationwide prospective cohort study of women. Environ Health Perspect 124:1344–1352; http://dx.doi.org/10.1289/ehp.1510363

Recent research in environmental epidemiology has attempted to estimate the effects of exposure to nature, often operationalized as vegetation, on health. Although many analyses have focused on vegetation or greenness with regard to physical activity and weight status, an incipient area of interest concerns maternal health and birth outcomes. This paper reviews 14 studies that examined the association between greenness and maternal or infant health. Most studies were cross-sectional and conducted in birth cohorts. Several studies found evidence for positive associations between greenness and birth weight and maternal peripartum depression. Few studies found evidence for an association between greenness and gestational age or other birth outcomes, or between greenness and preeclampsia or gestational diabetes. Several assessed effect modification by individual or area-level socioeconomic status and found that effects were stronger among those of lower socioeconomic status. Few studies conducted mediation analyses of any kind. Future research should include more diverse birth outcomes and focus on maternal health (especially mental health) and capitalize on richer exposure information during pregnancy rather than cross-sectional assessment at birth.

Surrounding greenness, but not blue space, was associated with lower odds of high depressive symptoms in this population of more than 9,000 U.S. adolescents. This association was stronger in middle school students than in high school students. Incorporating vegetation into residential areas may be beneficial for mental health.

Background:Recent evidence suggests that higher levels of residential greenness may contribute to better mental health. Despite this, few studies have considered its impact on depression, and most are cross-sectional.Objective:The objective of this study was to examine surrounding residential greenness and depression risk prospectively in the Nurses’ Health Study.Methods:A total of 38,947 women (mean age throughout follow-up 70 y [range 54–91 y]) without depression in 2000 were followed to 2010. Residential greenness was measured using the satellite-based Normalized Difference Vegetation Index (NDVI) and defined as the mean greenness value within 250-m and 1,250-m radii of the women’s residences in July of each year. Incidence of depression was defined according to the first self-report of either physician-diagnosed depression or regular antidepressant use. We used Cox proportional hazards models to examine the relationship between greenness and depression incidence and assessed physical activity as a potential effect modifier and mediator.Results:Over 315,548 person-years, 3,612 incident depression cases occurred. In multivariable-adjusted models, living in the highest quintile of residential greenness within 250m was associated with a 13% reduction in depression risk (HR=0.87 [95% confidence interval (CI): 0.78, 0.98]) compared with the lowest quintile. The association between greenness and depression did not appear to be mediated by physical activity, nor was there evidence of effect modification by physical activity.Conclusions:In this population of mostly white women, we estimated an inverse association between the highest level of surrounding summer greenness and the risk of self-reported depression. https://doi.org/10.1289/EHP1229