Low residential green space is associated with a “shift” towards a higher incidence of low IQ in urban childrenPrevious studies examining the benefits of residential greenspace show positive associations between neighborhood greenness and a range of health and well-being outcomes for children, including cognitive and behavioral benefits. Intelligence, however, has not been investigated as an outcome. This study contributes to the literature by examining whether the level of urbanicity can modify the association between residential green space and children's intelligence and behavior.
Data for this study are based on 310 twin pairs born in Belgium between 1980 and 1991. In 1992 and between 1996 and 1999, researchers assessed the intelligence of these children using the Wechsler Intelligence Scale for Children-Revised (WISC-R). The age range of the participating children at the time of assessment was 7-15 years; the mean age was 10.4 years. The Achenbach Child Behavior Checklist (CBCL) was used as a behavioral assessment in a subset of 442 children. Residential addresses of the children during pregnancy and during childhood at the time of the IQ measurement were geocoded. Information obtained from the European Environment Agency was used to estimate levels of seminatural, forested, blue, and urban green areas in several radius distances around the residential address of each participating child. Residential location was categorized as urban, suburban, or rural based on a map designating these areas. Estimates of traffic-related exposure near each resident were also calculated.
Most (41%) of the participating children lived in rural areas; 38% in urban areas, and 21% in suburban areas. Assessment results showed that intelligence and behavior were modified by the degree of urbanicity. For children living in urban environments, more residential greenspace was associated with higher IQ scores, and less residential greenspace with lower IQ scores. No such associations were found among children living in rural or suburban environments.
The fact that this study found an association between low residential green space in urban children and a “shift” towards a higher incidence of low IQ highlights important public health considerations. Policymakers and urban planners, for example, should make decisions informed by the beneficial impact of residential green space on the intellectual and behavioral development of children living in urban environments.
The Bottom Line