New Evidence on the Benefits of Green Space for Children

[This text was originally published in Catalan in Diputació de Barcelona’s EspaiS@lut bulletin.]

The year 2022 has been a prolific one in terms of the publication of studies providing new evidence on the benefits of exposure to green space during childhood.

In February, we learned that children living in areas with higher levels of PM_2.5 particulate matter air pollution and fewer green spaces faced a 62% higher risk of developing attention deficit hyperactivity disorder (ADHD). Conversely, children living in greener, less polluted areas had a 50% lower risk of developing the disorder. These were the findings of a Canadian study of 37,000 children published in Environment International. More specifically, the study showed that a 12% increase in the vegetation percentage around a child’s home was associated with a 10% decrease in ADHD risk.

Children living in areas with higher levels of PM_2.5 particulate matter air pollution and fewer green spaces faced a 62% higher risk of developing attention deficit hyperactivity disorder

Around the same time, a small study carried out in Italy with more than 300 children reached a revealing conclusion: greater exposure to green space during childhood is associated with lower levels of oxidative stress, regardless of physical activity. The study took into account not only greenness near the children’s homes but also vegetation in the vicinity of their schools. Concentration of the compound isoprostane in urine samples was used as an indicator of oxidative stress.

The study did not explore the possible mechanisms that could explain the lower level of oxidative stress in children with greater exposure to green space. Nevertheless, the lead author of the study, ISGlobal researcher Judith Garcia-Aymerich, proposed two hypotheses: 1) increased exposure to green space may contribute to children’s immune development by bringing them into contact with organisms that tend to colonise natural environments, or 2) contact with green space may increase vitamin D synthesis due to ultraviolet radiation from sunlight, since vitamin D acts as an antioxidant that prevents the negative effects of oxidative stress and inflammation.

Tree-Filled Spaces or Grass Cover?

These studies add to the scientific literature showing that green space in the vicinity of a person’s residence has a positive effect on health, especially because greenery improves mental health and promotes physical exercise, which reduces the risk of becoming overweight or obese. However, there are many types of green space and they do not all necessarily provide the same benefits. Another study published this year in Environment International provided new data on this issue.

The study, carried out in Canada with more than 27,500 children, showed that living in an environment with tree cover is associated with better early-childhood developmental outcomes than living in an environment with grassy spaces. Both types of vegetation were found to be associated with better developmental outcomes than areas dominated by paved surfaces.

Living in an environment with tree cover is associated with better early-childhood developmental outcomes than living in an environment with grassy spaces

The study noted that green space is associated with improved attention and memory in early childhood, higher academic achievement and fewer emotional and behavioural problems. The researchers also noted that all types of green space appear to promote health, but tree-filled areas may mitigate air pollution, noise and heat better than more open green spaces, while also doing more to support restoration from mental fatigue and the capacity for directed attention. Grassy spaces, in contrast, may do more to encourage group activities and therefore foster social well-being. Paved surfaces, meanwhile, are associated with more heat exposure and traffic-related air and noise pollution.

Growing Up Surrounded by Greenery Helps Children Behave Better

Finally, another study published in Environment International explored what types of urban design promote healthier behaviours in children. After estimating exposure to 32 characteristics of the urban environment near the homes and schools of more than 1,500 children in six European cohorts, the researchers concluded that urban areas with more vegetation, higher density of buildings and facilities, lower population density, and no major roads are associated with improved health behaviours in childhood. Specifically, the study suggested that children living in places with more natural spaces are more physically active, spend less time doing sedentary activities, get more hours of sleep and are more likely to walk or cycle to school.

Urban areas with more vegetation and a higher density of buildings and facilities are associated with improved health behaviours in childhood

All of these studies are worthy of being taken into account in urban design and planning. They represent this year’s research harvest, but by no means will they be the last of their kind. Scientific progress continues apace.