Exposure to greenspace during childhood has been associated with a wide range of both short-term and long-term health benefits. The studies in this section of the Digest focus on passive exposure to greenness at home, at school or in neighborhood environments, or presence of pet(s) in the home.

Exposure to greenspace early in life could result in beneficial structural changes in the brain

This study utilized data on 253 urban children (age 7-10) in Spain. The data included a satellite-generated estimate of the children’s lifelong (birth through the time of the study) exposure to residential greenspace and high-resolution 3D magnetic resonance images (MRI) of the children’s brain anatomy. Residential greenery was positively linked to tissue volume in various areas of the brain that are associated with cognitive functions – like attention and memory – that have been shown to be impacted by nature exposure.
Dadvand et al., 2018. The association between lifelong greenspace exposure and 3-dimensional brain magnetic resonance imaging in Barcelona schoolchildren.

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Mitochondria readings in primary children suggest that more green space during early life might promote health in later life

This study linked the results of over 400 buccal (cheek) cell swabs collected from 246 children (age 9-12) in Belgium with the level of greenness surrounding each child’s home and the distance from the child’s home to public green space. The results showed that more green space was associated with a higher mitochondrial DNA content (mtDNAc) for urban children, although the opposite was true for agricultural children. Results also showed a higher mtDNAc for children living closer to green space. Higher mtDNAc during childhood may suggest better adult health.
Hautekiet et al., 2022. Higher buccal mtDNA content is associated with residential surrounding green in a panel study of primary school children.
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Greenspace exposure and telomere length are positively linked in preschool children

Blood samples from 200 preschool children (age 5-7) in Iran were analyzed for leukocyte telomere length (LTL), which is considered to be a marker of aging. The shortening of telomeres suggests a higher risk of developing adverse health outcomes. Blood samples were linked to four different measures of greenspace exposure for each child. Results generally showed positive links between LTL and more exposure to greenspace.
Miri et al., 2020. Association of greenspace exposure with telomere length in preschool children.
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Subjective proximity to green spaces might not be associated with lower blood pressure in children

Data for this study was based on parent and child questionnaires and blood pressure (BP) readings of a large sample (N= 12,340) of Iranian children (age 7-18). Surveys completed by the children provided information about perceived proximity to greenness (green space within a 15-minute walk from home). Results showed reduced BP was associated with subjective proximity to green spaces. This reduction, however, was not statistically significant.
Abbassi et al., 2020. Subjective proximity to green spaces and blood pressure in children and adolescents: The CASPIAN-V study.
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Greater greenness near schools is associated with lower blood pressure, especially in overweight or obese children

This study included 9,354 children (age 4-17) from 62 schools in seven cities in northeast China. Two satellite-based measures (NDVI and SAVI) were used to assess greenness around the schools. Higher greenness was consistently associated with lower blood pressure in the children and lower levels of air pollution. The beneficial effects of higher greenness were stronger in children with higher BMI (body mass index) levels.
Xiao et al., 2019. Greenness around schools associated with lower risk of hypertension among children: Findings from the Seven Northeastern Cities Study in China.
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Green space around schools is linked to lower allostatic load in urban children

This study used seven biomarker assessments of 3,108 children (age 7) in Portugal and satellite-based estimates of their access to greenspace around their home and school. Children attending schools with more nearby greenspace exhibited significantly lower allostatic load (AL) scores than children attending schools with less nearby greenspace. No significant associations with AL were observed with accessibility to green space around the home. AL is a measure of biological multi-system dysregulation.
Ribeiro et al., 2019. Association between neighbourhood green space and biological markers in school-aged children. Findings from the Generation XXI birth cohort. 
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Pets can reduce the chances of elevated blood pressure and hypertension in children

Blood pressure (BP) readings on 9,354 children (age 5-17) in China indicated that children with dogs in the home were significantly less likely to have elevated BP and hypertension than children without dogs. These results are consistent with some other studies finding similar outcomes for adults with pets.
Xu et al., 2017. Prenatal and postnatal exposure to pet ownership, blood pressure, and hypertension in children: The Seven Northeastern Cities study.
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Formal educational programs are typically conducted indoors. Studies in this section of the Digest investigated the potential neurobiological benefits of conducting classes outdoors. These studies point to healthy diurnal cortisol rhythms, greater maturation of specific brain structures, and increased cognitive efficiency when in nature-based learning settings. 

Participating in outdoor education classes on a regular basis has a positive effect on children’s physical stress responses

A group of 37 students in Heidelberg, Germany participated in learning activities in a forest setting one full day per week throughout a school year. A control group of 11 students from the same school participated in a traditional class without outdoor teaching. Stress levels of all the students were measured via cortisol saliva samples taken during fall, spring and summer, three times over the course of the mornings. Students participating in the forest class showed a normal, healthy decline of cortisol during the school day; cortisol levels for the control group remained elevated throughout the day.
Dettweiller et al., 2017. Stress in school. Some empirical hints on the circadian cortisol rhythm of children in outdoor and indoor classes.
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Education outside the classroom can have a positive effect on biological stress regulation

Cortisol samples of 5th and 6th grade students in Germany showed less stress in students participating in an outdoor education experience than students without the outdoor experience. MRI results showed changes in brain structure for both groups, possibly due more to age than school experiences. Perceived autonomy support — apparently stronger in the outdoor classes — seemed to have a positive direct effect on the maturation of the anterior cingulate cortex in the brain.
Dettweiller et al., 2022. Choice matters: Pupils’ stress regulation, brain development and brain function in an outdoor education project.
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Children use greater cognitive resources while indoors than outdoors in nature to complete the same cognitive tasks

Data for this study was based on cognitive test results and neural responses of ten children (age 6-11) in the U.S. as they completed cognitive tasks in a natural outdoor environment and an indoor laboratory room. Readings from a head net with embedded electrodes worn by the children in each setting indicated that they performed cognitive tasks with significantly less neurological strain while outdoors vs. indoors. They also performed significantly better on a spatial working memory task when outdoors rather than indoors.
Torquati, Schutte & Kiat, 2017. Attentional demands of executive function tasks in indoor and outdoor settings: Behavioral and neuroelectrical evidence. 
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Nature-based therapy or nature therapy is the practice of using nature to promote growth and healing. As indicated by the following studies, nature therapy can take different forms and be conducted in different settings. The children involved in these studies include siblings of children with disabilities, children with emotional and behavioral concerns, and hospitalized children. Findings include improved physical and neuropsychological health for these populations.

EEG results show nature-based art therapy has a positive effect on siblings of children with disabilities

Twenty-nine siblings (age 7-13) of children with disabilities in South Korea were randomly divided into experimental and control groups. The experimental group (N=18) participated in eight weekly sessions of art therapy in a forest setting. The control group (N= 11) did not. Both groups completed pre- and post-assessments which included an electroencephalogram (EEG) to measure brain waves. Results showed more positive changes in brain waves in the experimental group than in the control group.
Kang, Kim & Baek, 2021. Effects of nature-based group art therapy programs on stress, self-esteem and changes in electroencephalogram (EEG) in non-disabled siblings of children with disabilities.
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Reduced salivary cortisol concentration indicates that horticulture activities can reduce stress in children with emotional and behavioral concerns

Twenty children (age 10-11) in South Korea with emotional and/or behavioral problems were randomly assigned to an experimental group or a control group. The experimental group participated in a once-a-week horticultural program over a period of nine weeks. The control group participated in alternative activities with similar levels of concentration and interest. An analysis of salivary cortisol samples taken before and after the program showed that the horticulture activities were effective in reducing stress.
Lee et al., 2018. A pilot study: Horticulture-related activities significantly reduce stress and salivary cortisol concentration of maladjusted elementary school children.
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Dish gardens in hospital rooms can promote children’s physical and neuropsychological health

This study, using a pre-test/post-test design with 54 hospitalized children (age 6-15) in Iran, randomly assigned children to either a hospital room with a dish garden or a room without a dish garden. Post-test results showed that blood pressure and respiration rates were significantly lower for the children in rooms with a dish garden rather than without the garden, along with improved mood and attention.
Yar & Kazemi, 2020. The role of dish gardens on the physical and neuropsychological improvement of hospitalized children.
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The following studies used both real and simulated nature exposure in a laboratory setting to investigate the impact of different aspects of nature on children’s concentration, attention, stress recovery and social interaction. Positive outcomes were linked to exposure to plants, animals and urban park soundscapes.

Decreased theta brain waves while viewing green foliage plants indicates that actual plants (vs. facsimiles) can improve concentration

Twenty-three children (age 11-13) in South Korea – each wearing a portable electroencephalogram (EEG) in a laboratory setting – were presented with four visual stimuli: an actual plant, artificial plant, photograph of a plant, and no plant. The EEG measured frontal alpha and theta brain waves. Results showed a significant decrease in theta waves with the presentation of actual plants but not with the other visual stimuli. This response indicated that viewing living plants prompted improvements in attention and concentration.
Oh, Kim & Park, 2019. Real foliage plants as visual stimuli to improve concentration and attention in elementary students.
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Electrocardiogram readings indicate that urban park soundscapes can help children recover from stress

After completing a task to induce mental stress, 53 children (age 8–12) in China were exposed to simulated urban park soundscapes while their physiological reactions were monitored by electrocardiogram readings from electrodes placed on their ankles and hands. Results showed that children’s physiological stress recovered after exposure to park soundscapes compared to ambient noise, but with significant gender differences. These results indicate that such urban park soundscapes as birdsong and stream sound could promote physiological recovery in children.
Shu & Ma, 2020. Restorative effects of urban park soundscapes on children’s psychophysiological stress.
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Eye tracking analysis shows that animal images engage greater social attention in children with autism than human images

Two groups of children in India – one with autism spectrum disorder (ASD), one without ASD – completed an eye tracking procedure during which they viewed images of human and animal faces. The children without ASD showed greater visual attention to faces than the children with ASD. The children with ASD, however, showed significantly greater attention to animal faces than to human faces.
Valiyamattam et al., 2020. Do animals engage greater social attention in autism? An eye tracking analysis. 
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