Satellite-derived data on greenness and access to green spaces are related to children's health indicators

There is increasing epidemiologic evidence on beneficial effects of
green environments on survival, perceived health and quality of
life, mental health, obesity and physical activity. However, most
studies have been conducted in adults. Further research to assess
the impacts of green environments on children's health is
warranted. Moreover, an investigation of potential mechanisms
underlying the associations is required. This thesis comprises
three publications, which are based on data from the German birth
cohorts GINIplus and LISAplus. The first publication assessed the
effects of residential greenness at the mother's residential
address as well as access to green spaces assessed by
satellite-derived data on birth weight of newborns. Greenness in a
500-m buffer around the mother's residential address at delivery
was positively associated with the birth weight of neonates. Air
pollution, noise, population density and maternal stress during
pregnancy did not mediate the discovered association. In the
stratified analyses, the association between greenness and birth
weight was more pronounced in mothers with low socioeconomic
status. Access to green spaces and birth weight were not
associated. Thus, increased accessibility to green spaces also does
not explain the observed association with greenness. The second
publication investigated whether access to green spaces as well as
residential greenness are associated with behavioural problems in
10-year-old children. Hyperactivity/inattention and peer
relationship problems were positively associated with increasing
distances to urban green spaces. The observed association with
hyperactivity/inattention was only statistically significant among
males. Children living further than 500 m away from any urban green
space had more overall behavioural problems than those living
within 500 m of an urban green space. Behavioural problems were not
associated with the distance to a forest or with residential
surrounding greenness. Thus, our findings suggest beneficial
effects of living in close proximity to well-maintained green
spaces on children's mental health. The third publication explored
for the first time an association between residential greenness and
blood pressure in 10-year-old children. The found association was
not influenced by environmental stressors (ambient temperature and
air pollution, noise annoyance, altitude and level of
urbanisation). The discovered link is in line with the existing
evidence from experimental studies and thus, with the
psychoevolutionary theory of Ulrich; the latter argues that green
environments mitigate stress by activating the parasympathetic
system. The associations were only significant in the urban Munich
study area but null in the rural Wesel area. This result might
indicate that children living in urbanised regions, which generally
lack vegetation, might bene t more from high residential greenness
than those from the rural areas. In summary, these results support
the hypothesis that better access to green spaces as well as higher
residential surrounding greenness bene t children health. The
results of my thesis suggest that greenness might improve health
through the mechanism of physiological stress alleviation. But,
contrary to my expectations, the observed effects of greenness and
green spaces could not be additionally explained by mediation via
physical activity, air pollution, noise, or urbanisation, possibly,
because of insufficient data. Thus, future research should test
more specifically what stands behind the discovered associations.
Finally, health impacts of green environmentson children's health
should be further investigated in different geographic areas with
incorporation of data on time spent in the neighbourhood and the
activities conducted as well as area-level socioeconomic status.