Fact Sheet: Children's Health and Nature

Childhood Obesity

Approximately 16% of US children (~ 9 million) aged 6-19 are overweight or obese [3]. According to the Institute of Medicine, childhood obesity has doubled over the past 30 years for preschoolers and adolescents, and more than tripled for children aged 6-11 years old [4]. 

Obesity-Related Diseases

Type-2 Diabetes Due to the drastic increase in the prevalence of pediatric diabetes over the past few decades, the definition has changed from “adult-onset” diabetes to type-2 diabetes. Approximately 176,500 children and adolescents suffer from diabetes [5].

Asthma Currently 9.4% of children in the US have asthma [6]. Overweight children are at an increased risk for developing asthma and other respiratory problems and for being hospitalized for asthma [7, 8].

Hypertension 1 in 10 children with a BMI* within or above the 95th percentile have hypertension (vs. only 2.6% with a BMI <85th percentile) [9].

Cardiovascular Disease Overweight adolescents are at increased risk of coronary heart disease and earlier death [1]. Most overweight children have at least one risk factor for cardiovascular disease, including higher cholesterol levels, abnormal glucose tolerance, high blood pressure, and elevated triglycerides [10]. The American Academy of Pediatrics recommends screening overweight children for high cholesterol and prescribing cholesterol-lowering drugs if needed [11].

*BMI = Body- mass index; calculated using the formula: weight (lb) / [height (in)] 2 x 703. To calculate BMI for children/adolescents, visit: http://apps.nccd.cdc.gov/dnpabmi/Calculator.aspx. 

Attention-Deficit/Hyperactivity Disorder (ADD/ADHD)

According to the Centers for Disease Control and Prevention (CDC), ADD/ADHD is a serious public health problem that impacts approximately 4.3% of children aged 4-17 years old [12]. It impairs school performance and socialization and may persist into adulthood.

Vitamin-D Deficiency

Lack of an appropriate amount of vitamin D in children can cause rickets; a disease characterized by bone deformities and growth retardation. Long term deficiency can lead to osteoporosis. Sunlight exposure for 10-15 minutes at least twice a week is sufficient for the body to produce the necessary amount of vitamin D [13].

Nature and Health

Unstructured outdoor play time is important for children’s overall well-being. How does nature play a role in children’s health? Highlights of published literature supporting the health benefits of the natural environment are presented below.

Nearby Nature: A Buffer of Life Stress Among Rural Children [14]

Childhood stress has become an increasing issue of concern for pediatricians in America. The workload of school and extracurricular activities has the potential to create more stress upon a child, which can affect the child’s development. Evidence has shown that the outdoors is a stress reliever to highly stressed children. A study examined whether nearby nature acts as a buffer of life stress among rural elementary school children. The authors determined if the child lived near a natural environment, and then examined the child’s self-worth and levels of psychological distress. Contact with nature not only decreased their stress, but higher amounts of exposure to natural environments indicated lower levels of stress in a child.

Coping with ADD: The Surprising Connection to Green Play Settings [15]

An increasing amount of evidence is showing that exposure to natural environments can mitigate a child’s attention disorder. Experimenters of a 2001 study analyzed this concept by surveying parents to compare their child’s attentional functioning when engaging in leisure activities in indoor vs. outdoor settings. Results included that children had better attentional functioning after activities in greener settings. The greener the setting, the less severe the symptoms of the child’s attention disorder.

A Potential Natural Treatment for Attention-Deficit/Hyperactivity Disorder. Evidence from a National Study [16]

A follow-up nationwide study published in The American Journal of Public Health by the same authors examined if “green” settings reduced symptoms of ADHD. Green outdoor after-school and weekend activities were compared to activities that were in built indoor and outdoor settings. They found that “green outdoor activities reduced symptoms significantly more than did activities conducted in other setting, even when matched across all settings”. However, this study was not randomized or controlled, and the “green activities” were not uniformly defined. The authors published an August 2008 study in The Journal of Attention Disorders showing that a 20-minute walk in nature is associated with better concentration in children with ADHD [17]. Further research on this subject will help us better understand the true impact of the natural environment on attention functioning.

Outdoor Activity Reduces the Prevalence of Myopia in Children [18]

A population-based study published in 2008 determined if near-distance, mid-distance, and outdoor activities were associated with the prevalence of the eye condition myopia in 4,132 children aged 6 and 12. Authors found that higher levels of outdoor time spent was associated with less myopia and increased hyperopic mean refraction in 12 year old participants. Children with high near-distance activity and low outdoor activity had two- to three-fold higher odds of having myopia than normal. Authors concluded that more research is needed in this matter; however, outdoor activity should be promoted by the public health community and included in school curricula.

Children Living in Areas with More Street Trees Have Lower Prevalence of Asthma [19]

A recent ecological study conducted in New York City has suggested that being exposed to a natural environment may be protective against early childhood asthma. Streets with a high tree density were positively associated with a lower prevalence of early childhood asthma in 4-5 year olds. Further research is currently being conducted to determine the extent to which the trees play a role in the control of pediatric asthma.

The Mental and Physical Health Outcomes of ‘Green Exercise’ [20]

One study showed the synergistic health effects between physical activity and exposure to nature (“green exercise”). In this study, adult subjects ran on a treadmill while being shown four different themes of pictures: (a) rural pleasant, (b) urban pleasant, (c) rural unpleasant and (d) urban unpleasant photographs (a control group ran without any photographs for comparison). The researchers measured subjects’ blood pressure, self-esteem, and mood. The study concluded that the rural and urban pleasant nature picture not only showed a significant reduction in blood pressure, but also a more positive effect on mood. Furthermore, participants in the rural pleasant group had the largest reduction in blood pressure. The authors suggest that “green exercise” not only has a greater effect on blood pressure than exercise alone, but also is beneficial for people’s mental health.

View Through a Window May Influence Recovery from Surgery [21]

Nature has always been known to have a restoring or therapeutic power on humans. There has been evidence showing that people can recover from a surgery or deal with pain better if exposed to a natural environment. A study from in Science compared 23 matched pairs of patients who underwent a cholecystectomy (a common type of gall bladder surgery). The post-surgery patients were randomly-assigned to either rooms facing a brick building, or a room with a view of a natural environment (trees, grassy field). Investigators found that those facing nature had shorter post-operation stays, less negative comments from nurses, took less analgesics, and had decreased amounts of post-operative patients. The study concluded that viewing nature alone can aid in the path to recovery.

Distraction Therapy with Nature Sights and Sounds Reduces Pain During Flexible Bronchoscopy: A Complementary Approach to Routine Analgesia [22]

Natural environments can also act in reducing pain. A randomized controlled trial used distraction therapy (in the form of sights and sounds of nature) in the operating room during a flexible bronchoscopy through conscious sedation. Patients then rated the level of pain and anxiety they experienced during the operation. The authors found that pain control was four to five-fold better for the intervention group than the control groups. The study suggests that clinicians should supplement analgesic medication with an inexpensive, non-invasive method of distraction therapy.

Effect of Exposure to Natural Environment on Health Inequalities: An Observational Population Study [23]

A 2008 study published in Lancet investigated if exposure to green space (i.e. parks, forests, river creeks, play fields) is a determinant of good health. Authors classified more than 40 million people from England based on level of income and access to green space. All-cause, circulatory, lung cancer, and intentional self-harm mortality records were obtained from 2001-2005 to determine if there was an association with income deprivation and exposure to green space. The major finding was that the group living in the greenest areas had the lowest level all-cause mortality and mortality due to circulatory diseases related to income deprivation. The authors suggested that exposure to natural environments could play a vital role in reducing health inequalities.

Neighborhood Greenness and 2-Year Changes in Body Mass Index of Children and Youth [24]

A retrospective cohort study appearing in the December 2008 issue of The American Journal of Preventive Medicine followed 3 to 16 year-old low-income children from Indiana for two years. Authors calculated their change in BMI and measured the amount of green space in each child’s neighborhood using satellite images. After adjusting for potential variables such as age and gender, it was found that higher greenness was associated with lower odds of increased change in BMI (OR: 0.87, 95% CI: 0.79-0.97). Authors suggested that efforts to get children outside and engaged in healthy behaviors should be promoted as a means to help combat childhood obesity.

The Importance of Play in Promoting Healthy Child Development and Maintaining Strong Parent-Child Bonds [25]

The American Academy of Pediatrics (AAP) released a Clinical Report in 2007 on the importance of free play in the development of healthy children. Free play aids in physical, emotional, cognitive, and social development of a child. They stated that the benefits of play include healthy brain development, a more developed imagination, dexterity, emotional strength, and physical strength. The AAP suggests to parents and pediatricians to allow children to have more unstructured play.

Active Healthy Living: Prevention of Childhood Obesity Through Increased Physical Activity [26]

Allowing children free, unstructured outdoor play is an important way to help them get physically active. The AAP issued a policy statement in 2006 to pediatric health care providers on ways to increase physical activity in children and adolescents. The authors stated that lifestyle-related physical activity, as opposed to aerobics or calisthenics, is critical for sustained weight loss in children, and recommended free, unorganized outdoor play as a method of physical activity. Infants and toddlers should be allowed outdoor physical activity, unstructured free play, and exploration. The AAP encourages parents to get their children outside as much as possible.

Recommendations

Centers for Disease Control and Prevention: The CDC encourages children to get at least 60 minutes of physical activity most days of the week, preferably daily. Because nature has the potential to improve one’s physical, mental and social health, the CDC advises children to engage in healthy outdoor activities in nature and parks. For more information, visit: http://www.cdc.gov/Features/ParksAndTrails/.

U.S. Department of Health and Human Services: The 2008 Physical Activity Guidelines advise children to be physically active at least an hour a day through age-appropriate, enjoyable activities such as hiking, bicycling, climbing trees, or going to the park. These guidelines can improve children's cardiorespiratory fitness, cardiovascular and metabolic health, bone health, and body composition. The 2008 Physical Activity Guidelines are available at: http://www.health.gov/PAGuidelines/guidelines/default.aspx.

American Academy of Pediatrics: The American Academy of Pediatrics recommends that pediatricians promote free, unstructured play and discourage excessive passive entertainment such as TV, internet, and video games to 2 hours a day [27]. In addition, parents are advised to record the number of times each week that their child spends outdoors for at least 30 minutes. The Clinical Report on the importance of play for children is available at: http://aappolicy.aappublications.org/cgi/content/full/pediatrics;119/1/182, and the Policy Statement on increasing physical activity in children is available at: http://aappolicy.aappublications.org/cgi/content/full/pediatrics;117/5/1834.

American Medical Association and American College of Sports Medicine: A program was launched by the American Medical Association and the American College of Sports Medicine to encourage physicians to prescribe exercise to their patients. Two-thirds of patients from a survey suggested that they would be more inclined to exercise if told by a physician. The program recommends 30-40 minutes of physical activity, five days a week. For more information, visit http://www.exerciseismedicine.org/.

Conclusion

There is a strong body of evidence attributing improved health with physical activity. In addition, there is evidence suggesting that nature specifically can improve attention and other psychological aspects of health. Playing in nature can positively impact children’s health and well-being. We encourage parents and caregivers to get your children out into the natural environment. Together we can teach them how to protect their health and the environment.

“Time in nature is not leisure time; it’s an essential investment in our children’s health.” Richard Louv, author of Last Child in the Woods [28]

Sources

[1] Ludwig DS (2007). New England Journal of Medicine, 357(23): 2325-27. [2] Perrin JM, Bloom SR & Gortmaker SL (2007). JAMA, 297(24): 2755-59. [3] Centers for Disease Control and Prevention (2002). Prevalence of Overweight among Children and Adolescents. [4] The Institute of Medicine (2005). Preventing Childhood Obesity: Health in the Balance. [5] National Institutes of Health (2006). Overview of Diabetes in Children and Adolescents. [6] Centers for Disease Control and Prevention (2008). National Center for Health Statistics: Asthma. [7] Schachter LM (2001). Thorax, 56(1):4-8. [8] Bender B, et al (2007). Pediatrics, 120:805-13. [9] Sorof JM, et al (2004). Pediatrics, 113(3):475-82. [10] Dietz WM (1998). Pediatrics, 101(3):518-525. [11] Daniels SR, Greer FR & the Committee on Nutrition (2008). Pediatrics, 122(1):198-208. [12] Centers for Disease Control and Prevention (2005). Mental Health in the United States. [13] Brender E, Burke A, Glass RM (2005). JAMA, 294(18):2386. [14] Wells NM & Evans GW (2003). Environment and Behavior, 35(3):311-330. [15] Taylor AF, Kuo FE & Sullivan WC (2001). Environment and Behavior, 33(1):54-77. [16] Kuo FE & Taylor AF (2004). The American Journal of Public Health, 94(9):1580-86. [17] Taylor AF & Kuo FE (2008). The Journal of Attention Disorders, 0: 1087054708323000v1. [18] Rose KA, et al (2008). Ophthalmology, 115(8): 1279-1285. [19] Lovasi GS, et al (2008). Journal of Epidemiology and Community Health, 0:1-3. [20] Pretty J, et al (2005). International Journal of Environmental Health Research, 15(5):319-37. [21] Ulrich RS (1984). Science, 224(4647):420–421. [22] Diette GB, et al (2003). Chest, 123(3):941-8. [23] Mitchell R & Popham F (2008). Lancet, 372 (): 1655-60. [24] Bell JF, Wilson JS, Liu GC (2008). American Journal of Preventive Medicine, 35(6): 547-533. [25] Ginsburg KR, et al (2007). Pediatrics, 119(1):182-191. [26] Council on Sports Medicine and Fitness and Council on School Health (2006). Pediatrics, 117(5):1834-1842. [27] Committee on Public Education (2001). Pediatrics, 107(2): 423. [28] Louv R (2005). Last Child in the Woods. Algonquin Books, Chapel Hill, North Carolina.