Invited Perspective: A Natural Prescription for Hypertension?

Poets, artists, and naturalists have long extolled the beauty of natural landscapes and their ability to rejuvenate and inspire.However, this love of "nature" is partial to "natural spaces"; that is, wild landscapes like those now found in nature preserves around the world.However, although urbanization and lifestyle changes have reduced the possibilities of direct, everyday contact with nature "out there," nature's influence does not end at the boundaries of nature parks.It is everywhere with us-within the cities we build, near the houses we live in, and around the roads we travel every day.Even in urban surroundings, nature works it magic.Living in urban areas of higher surrounding greenness is associated with lower levels of stress, depression, insulin resistance, diabetes, stroke, all-cause mortality, and cardiovascular mortality.1,2 In areas of low greenness, wellpositioned vegetation, such as street trees, can reduce air pollutants known to have adverse health effects.3 Adding to this body of knowledge, in this issue of Environmental Health Perspectives, Zheng et al. 4 report potential protective effects of neighborhood greenness against incident hypertension.Zheng et al. compared levels of residential greenness in Taiwan and found that people living in neighborhoods with lower levels of greenness had a higher risk of hypertension compared with those living in neighborhoods with more green space.These findings are particularly noteworthy because they are derived from a large cohort of 125,537 participants recruited over a 15-y period.They strengthen the evidence for an association between exposure to greenness and blood pressure previously reported in cross-sectional studies.[5][6][7] The effect sizes are also comparable.The 24% lower risk of hypertension for each 0.1-unit increase in normalized difference vegetation index reported by Zheng et al. is similar to estimates previously reported, ranging from 17% 8 to 36% 6 lower odds of hypertension.Even though these findings collectively support the notion that living among greener surroundings may lower the risk of hypertension, it is not clear why and how this might be so.The authors found the potential antihypertensive effect of greenness could not be attributed to a reduction in exposure to ambient fine particulate matter [PM ≤2:5 lm in aerodynamic diameter (PM 2:5 )].Exposure to PM 2:5 has been extensively linked to high blood pressure and excess cardiovascular disease risk.9 In previous work, we found that the association between PM 2:5 exposure and arterial stiffness was weakened by residential greenness, 10 and that the association between PM 2:5 and cancer mortality was mitigated