Health equity means that all people have a fair and just opportunity to be as healthy as possible. Achieving health equity in a community requires a reduction and eventual elimination of health disparities (differences) affecting economically or socially disadvantaged groups. The aim of this systematic review of the literature was to gather evidence about whether green space can contribute to limiting health disparities and moving toward health equity.
The main question guiding the review focused on whether or not green space shows more protective health effects for disadvantaged populations than for privileged groups. “Disadvantaged” included individuals and groups with low socioeconomic status (SES) or who identify as a racially/ethnically minoritized group. Three additional questions were used to guide the review: (1) Does type of green space matter? (2) Does the type of health outcome matter? and (3) Does the continent matter? A total of 90 studies were included in the review. Most of the papers (N=85) examined the health effects by SES; 20 papers by both SES and race/ethnicity. Four green space categories were considered: green land cover, public green space, gardens, and nature-based programs. Of these, green land cover and public green spaces were studied most frequently. Health outcome types studied most frequently were related to obesity and cardiovascular health/disease. While the included studies focused on people living in every continent except Africa, most of the studies focused on North America and Europe. Sample size of the studies ranged from 106 (individual-level study) to over 97 million (ecological study). Most of the studies were cross-sectional, a few longitudinal, and none were experimental. All of the studies were published between 2003 and 2019; most in the 2012–2019 period.
An analysis of the data showed that green space had more protective effects for low-SES groups than for high-SES groups. While these findings were consistent across continents, the stronger protective effects for lower-SES populations were more notable in Europe than North America. Public green spaces/parks provided stronger protective effects for lower-SES populations than green land covers, especially when larger distances around one's home were considered. The stronger beneficial effects for low-SES people (as compared to high-SES people) were more pronounced for general health and cardiovascular health/disease than birth outcomes. The data also showed that for racially/ethnically minoritized people, green space might have stronger protective effects (as compared to white people) for cardiovascular health/disease. The overall data, however, showed no notable differences in the protective effects of green space between racial/ethnic groups. The fact that only a relatively small sample of articles (N=24) considered the health effects of green space by race/ethnicity suggests that more research on this topic is warranted.
Health disparities are potentially avoidable. This study showed that increased exposure to green space “could be used as a tool to promote health equity.” Implications of these findings include (a) prioritizing public green space in low-SES communities over other types of green space and (b) considering the provision of green space for low-SES residents beyond the immediate surroundings of their home.
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