Greenspace seems protective of both high and low blood pressure among residents of an Alpine valley

Background: There is some data suggesting that residential greenspace may protect against high blood pressure in urbanized areas, but there is no evidence of effects on hypotension, in less urbanized areas, and in idiosyncratic geographic contexts such as mountain valleys. Objectives: The current study aimed to investigate the associations between residential greenspace and blood pressure in an alpine valley in Austria. Methods: We conducted a cross-sectional survey of a representative sample of 555 adults living in the Lower Inn Valley, Austria. Several definitions of blood pressure were employed: continuously-measured systolic (SBP) and diastolic blood pressure (DBP), doctor-diagnosed hyper-and hypotension, and high-and low blood pressure medication use. Greenspace metrics considered were: Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and tree cover as measures of surrounding greenness in circular buffers of 100 m, 300 m, 500 m, and 1000 m around the home; distance to different types of structured green space; and having a domestic garden and a balcony. Relationships were examined across different definitions of blood pressure and greenspace and evaluated for potential effect modification by demographic factors, presence of a domestic garden/balcony, adiposity, and traffic sensitivity. Results: Higher overall greenness was associated with 30-40% lower odds of hyper/hypotension and 2-3 mm Hg lower SBP. Similar pattern was revealed for tree cover, however, associations with hypertension were less consistent across buffers, and SBP and DBP were lower only in association with greenness in the 100-m buffer. Having a domestic garden also seemed protective of high DBP. Residing near to forests, agricultural land, or urban green spaces was not related to blood pressure. Higher NDVI500-m was stronger associated with lower SBP in those having a domestic garden, while the effect on DBP was stronger in overweight/obese participants. Conclusion: These findings support the idea that greenspace should be considered as protective of both high and low blood pressure, however, underlying mechanisms remain insufficiently understood.