Green spaces within and around city schools improve the mental development of young children, a study has found.
The findings may partly be explained by reduced exposure to traffic pollution, experts believe. Other influences could include the psychological effect of having views of fields and trees rather than roads and buildings.
The Spanish researchers found that each step increase in surrounding greenness led to a five per cent improvement in the development of short-term, or working, memory over a period of one year.
It also improved the progress of “superior working memory” – the ability to update memories with changing information – by six per cent, and reduced inattentiveness.
Computer analysis suggested that carbon from traffic fumes might account for up to 65 per cent of the trend.
The researchers carried out mental performance tests on 2,593 children aged seven to 10 attending 36 primary schools in Barcelona every three months for a year.
At this age, children’s brains are rapidly developing and their mental abilities improving. Over the study period participants’ overall working memory increased by an average of 22.8 per cent, and superior working memory by 15.2 per cent, while inattentiveness decreased by 18.9 per cent.
Urban areas are characterised by a network of non-natural built-up infrastructures with increased pollutant levels
Exposure to green spaces was assessed with the help of satellite images. The scientists applied a measurement called Normalised Difference Vegetation Index (NDVI) based on the reflective properties of land surfaces.
The results are reported in the journal Proceedings of the National Academy of Sciences.
Led by Payam Dadvand, from the Centre for Research and Environmental Epidemiology in Barcelona, the researchers wrote: “Approximately one half of the world population lives in cities, and it is projected that by 2030, three of every five persons will live in urban areas worldwide.
“Urban areas are characterised by a network of non-natural built-up infrastructures with increased pollutant levels and less green environments. Children’s exposure to these pollutants such as air pollution and noise has been associated with detrimental impacts on their cognitive development.
“Our findings suggest a beneficial impact of green space exposure on cognitive development, with part of this effect resulting from buffering against such urban environmental pollutants.”
Schools that increased greenness within their boundaries by the amounts observed in the study could reduce the proportion of children with impaired superior working memory development by nearly nine per cent, said the researchers.