Children brought up in cities with access to green environments have higher intelligence and lower incidences of behavioural problems, a study suggests.

Greater levels of residential green space in urban areas could lead to a “shift in population IQ”, with children attaining better results, according to a research team at the Universities of Hasselt and Ghent in Belgium.

Though several previous studies have linked access to green areas with positive outcomes for child development, the study is the first to examine the connection with IQ.

The scientists assessed more than 700 people aged between 8 and 15, and found a 3.3 per cent increase in space within a 3km radius from the residential address was associated with a 2.6-point higher total IQ.

The differences among children with lowest IQs was found to be the most pronounced, where even small improvements could have a considerable impact.

Furthermore, the proximity to green areas was also associated with a reduction in “problem behaviour”, such as attention issues and aggression.

The research team said the nature of the study showed the associations were consistent across different socio-economic groups.

The results “show that well-planned green cities are important to create an optimal environment for children to develop their full potential,” Esmée Bijens, a researcher at UHasselt and UGhent and co-author of the study, told The Independent.

“I believe green space is important for children on several levels,” she said.

“Access to nearby natural outdoor play spaces may enhance children’s executive functioning, and a meta-analysis revealed that the greening of school yards across multiple sites in North America and Western Europe have been associated with better psychological well-being and improved school performance among pupils.”

Dr Bijens added: “Our results are not biased by the socioeconomic background of the participants. The association between green and intelligence were found in children from parents with a high as well as a low educational level.”

The scientists said though the contribution of proximity to green space to an individual’s IQ might be moderate, high residential green space in children living in an urban area could cause a shift in population IQ towards a lower incidence of a low IQ.

The study notes that green spaces, such as parks, grassy areas, gardens and areas with trees, provide environmental benefits by reducing air and noise pollution.

The authors said: “Higher residential green space is associated with lower ambient air pollution and noise exposure. Both have been associated with diminished cognitive development. Furthermore, from a health perspective, green space promotes physical activity and stress reduction.

“Apart from the promotion of physical activity, green space in the living environment could also lead to more social contacts. In addition, higher levels of neighbourhood green space were associated with significantly lower levels of symptoms of depression, anxiety, and stress.”

The scientists used satellite mapping to assess the study participants addresses and their distances from green spaces

The computer modelling the team used also adjusted for “potential confounding factors”, which included sex, age, parental education and neighbourhood household income.

“This study demonstrates that green spaces such as the proximity of a city park can make a difference for the development of children,” said Professor Tim Nawrot from the University of Hasselt

“These findings are relevant for policy makers and urban planners to create an optimal environment for children to develop their full potential.”