Children growing up in cities with more access to green space have higher intelligence levels, a new study suggests.

The research involving more than 600 children aged 10 to 15 showed a 3 per cent increase in the greenness of their neighbourhood raised their IQ score by an average of 2.6 points. Richer and less advantaged areas both saw the effects.

The positive effects of green spaces on children’s cognitive development are already well documented, but the study from Hasselt University in Belgium was the first to look specifically at IQ.

The increase in IQ points was particularly significant for those children at the lower end of the spectrum, where small increases could make a big difference, The Guardian reports.

“There is more and more evidence that green surroundings are associated with our cognitive function, such as memory skills and attention,” said Tim Nawrot, a professor of environmental epidemiology who co-authored the study.

“What this study adds with IQ is a harder, well-established clinical measure. I think city builders or urban planners should prioritise investment in green spaces because it is really of value to create an optimal environment for children to develop their full potential.”

The study, published in the journal Plos Medicine, used satellite images to measure the level of greenness in neighbourhoods, including parks, gardens, street trees and all other vegetation.

The average IQ score was 105 but the scientists found 4 per cent of children in areas with low levels of greenery scored below 80, while no children scored below 80 in areas with more greenery.

The benefits of more greenery were not replicated in suburban or rural areas.