Exposure to green environments has been demonstrated through experimental studies to bust stress by decreasing blood pressure (BP), among other sympathetic nervous system effects. However, the impact of greenness on BP has not yet been studied by observing children in their natural environment. The authors assessed whether greenness surrounding the home is associated with BP in 2,078 10 year-old German children living in urban and rural areas and participating in large epidemiological studies. Greenness surrounding the home was measured using the Normalized Difference Vegetation Index (NDVI), derived from satellite images, in a circular 500-m buffer around each participant's home address.
The authors found that systolic and diastolic BP of children living in homes surrounded by low and moderate greenness was higher than the systolic and diastolic BP of children living in areas with a high level of greenness. These findings were not the result of environmental stressors such as air temperature, air pollution, noise, altitude and level of urbanization. When the authors looked at rural vs. urban children, the associations between greenness and blood pressure were significant among children living in the urban area but not for those in the rural area.
The authors concluded that lower residential greenness was associated with higher BP in 10 year-old children living in an urbanized area and suggested that future studies look at the influence of participants' age, geographical area and urbanization level, socioeconomic status and time spent outdoors on these associations.
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