30.09.2016 Natural Health

Green spaces boost health

In an increasingly urbanised world, planning greener environments around us is more important than ever, reports Peter Dingle PhD

Growing up in the ’60s there was always lots of space to play on the street or out in the big backyards, nearby parks, creeks and the beach. While we have lost a lot of these spaces, research is showing that the more “green” we are surrounded with the healthier it is for us.

Invariably, as the suburbs spread out we lose more open space and green and private gardens are either small or non-existent. Globally, the same situation is occurring with a dramatic demographic shift towards urbanisation. Between 2000 and 2050, the proportion of people living in urban areas is projected to rise from 46.6 to 69.6%, giving fewer people around the world access to green spaces and their potential health benefits.

Humans exhibit more than just a preference for natural scenes and settings; they suffer health problems when their environment and lifestyle causes them to become nature-deficient.

Increasing evidence indicates that nature provides restorative experiences that directly affect people's physical, social and mental wellbeing and health in a positive way.

An emerging body of evidence has linked exposure to green spaces with improving both perceived and objective physical and mental health, wellbeing and decreased mortality - including living near to, walking in it and even gardening.

Underlying mechanisms of health benefits of green spaces are not well understood, but research suggests that increasing physical activity, reducing psychological stress, anxiety and depression, while increasing social contacts/cohesion and a sense of community belonging 1, reducing noise and air pollution levels, and moderating ambient temperature may underlie such benefits .

Fewer deaths

A recent study found that living in more densely vegetated areas was associated with fewer deaths from causes other than accidents.

Using data from the Nurses’ Health Study, after controlling for factors including socioeconomic status, race, smoking, and whether the women lived in a rural or urban area, the researchers estimated a 12% lower rate of non-accidental death between women who lived in the most densely, versus least densely, vegetated areas. When looking at specific causes of death, the researchers estimated a 41% lower rate of kidney disease mortality, a 34% lower rate of respiratory disease mortality, and a 13% lower rate of cancer mortality in the women who lived in the greenest areas, compared with those in the least green areas 2.

A study of adolescents reported lower risk factors associated with cardiovascular disease and diabetes in greener areas 3. In a cross-sectional study of 11,404 adults in Perth Western Australia, the odds of hospitalisation for heart disease or stroke was 37% lower, and the odds of self reported heart disease or stroke 16% lower among adults with highly variable greenness around their home, compared to those in neighborhoods with low variability in greenness. The odds of self reported heart disease or stroke decreased by 7% per unit with every 25% increase in the level of greenness 4.

In a controlled experiment 14 children undertook two, 15 minute bouts of cycling at a moderate exercise intensity while, in one situation, viewing a film of cycling in a forest setting and another with no visual stimulus. The systolic blood pressure (SBP) 15 min post exercise was significantly lower following green exercise compared to the control condition 5. The surrounding environment can also significantly impact healing outcomes for patients.

Green views from windows have been shown to aid post-operative recovery .

Weight control benefit

The rise in obesity is well documented and while there are many contributing factors, a systematic review of greenspace research from 60 studies reported the majority (68%) of papers found a positive association between green spaces and obesity-related health indicators 6. One study found that increased vegetation was associated with reduced weight among young people living in high population densities 7 and across eight European cities, people were 40% less likely to be obese in the greenest areas 8.

However, not all spaces are green that can have these benefits.

There was also variation by green space type, with relationships found only for access to beaches in New Zealand 9 and park playgrounds among children in Canada 10. Overall, the majority of studies found some evidence of a relationship with weight and green space 6.

In children, exposure to greenness has been associated with reduced sedentary behavior and obesity . In study of 3,178 schoolchildren (9-12 years old) a 25% range increase in residential surrounding greenness was associated with 11-19% lower relative prevalence of overweight/obesity and excessive screen (television and computing) time. Similarly, residential proximity to forests was associated with 39% and 25% lower relative prevalence of excessive screen time and overweight/obesity, respectively 11.

Walking

The lower prevalence of obesity, adverse health and improved health outcomes may be attributable to higher levels of physical activity, such as neighborhood walking which is positively influenced by the natural environment. Walking is the most popular physical activity 12, and levels of recreational walking have been linked the distance to and attractiveness of local parks and ovals 13. Many studies have reported that adults with access to a large high-quality park within walking distance (within 1600 m) from home have elevated levels of walking 14 and in general live longer 15. In a review of 50 studies, 20 (40%) reported a positive association between green space and physical activity, including children and older people.

While walking itself can reduce stress, walking in a natural setting provides greater stress relieving benefits 16.

Being around vegetation can lead to better mental health and less stress , positive emotions , focus and attention 17, as well as reduced stress 18. While walking itself can reduce stress, walking in a natural setting provides greater stress relieving benefits 16. There is also evidence that exposure to natural settings can lower blood pressure, reduce mental fatigue, reduce negative feelings, increase attentional capabilities, and enhance effectiveness in dealing with major life issues.

The most preferred parkland settings have repeatedly been shown to be those where human influences do not dominate the natural elements 19. Accessible green spaces are ‘escape facilities’, and lack of access to green space contributes to poor mental health 20. Some of the more potent restorative effects of nature relate to being able to ‘get away’ from everyday settings and immerse oneself in an extensive natural setting that creates a sense of being in a ‘whole other world.’ A “quiet fascination, characterised by a moderate level of effortless attention coupled with aesthetic beauty in the setting, will foster a more deeply beneficial restorative experience” 21.

In one study after a 40 minute test to exhaust their directed attention capacity, participants were randomly assigned 40 minutes walking in a local nature preserve, walking in an urban area, or sitting quietly while reading magazines and listening to music. Those who had walked in the nature preserve performed better than the other participants on a standard proofreading task. They also reported more positive emotions and less anger.

Better mental health for kids

Green spaces have been associated with improved mental health in children. Neuropsychiatric problems including behavioral problems occur in 10–20% of children worldwide. The most commonly diagnosed behavioral disorder among children and adolescents is attention deficit/hyperactivity disorder (ADHD). In one study investigating ADHD symptoms they found statistically significant inverse associations between green space playing time and total difficulties, emotional symptoms, and peer relationship problems; between residential surrounding greenness and total difficulties and hyperactivity/inattention and ADHD total and inattention scores; and between annual beach attendance and total difficulties, peer relationship problems, and prosocial behavior 22.

In another study results indicate that children with ADD function better than usual after activities in green settings and that the “greener” a child’s play area, the less severe his or her attention deficit symptoms 23.

Thus, contact with nature may support attentional functioning in a population of children who desperately need attentional support.

Recent research suggests an association between increased residential greenness and improved birth outcomes.

And the benefits don’t seem to end there. Recent research suggests an association between increased residential greenness and improved birth outcomes. The researchers assessed the relationship between birth weight, preterm birth, and residential greenness among 64,705 births recorded and reported that increases in greenness were associated with higher birth weight for babies born at term (37 weeks or later) and decreased likelihood of having a moderately or very preterm birth, or a small-for-gestational-age baby 24.

In a study of 2,393 pregnant women, on average, babies born to mothers living in "greener" areas had higher birth weights and slightly larger head circumference compared to babies whose mothers lived in areas with lower plant cover. The effects were strongest in babies born to mums with lower education, suggesting that increasing green space may have the most benefit in socioeconomically deprived areas 25.

Unfortunately, as the urban expansion and infill continues we are no longer getting our daily exposure to green environments. Increasing housing density can contribute to urban sustainability, but the loss of private garden space must be compensated for by the availability of quality public open space and ‘green infrastructure’ throughout urban areas.

While the health of the populations is important, nature provides critical ‘ecosystem services’ essential for our long term survival. These include filtering air and water, absorbing wastes, maintaining beneficial insect and bird populations, and nutrient cycling. There is also evidence that green spaces in urban areas help to moderate the urban climate and, in some cases, could offset the heatwaves associated with global warming. Perhaps we need to rethink our building incorporating more green elements, as well as our ever increasing encroachment on our green spaces.

  1. Hartig T, et al. 2014
  2. James P, et al.2016
  3. Dengel et al. 2009
  4. Gavin Pereira et al 2012
  5. Duncan, et al 2014.
  6. Lachowycz and Jones 2011
  7. Liu GC, 2007
  8. Ellaway et al 2005
  9. Witten K 2008
  10. Potwarka 2008
  11. Dadvand et al 2014
  12. McCormack et al, 2003
  13. Giles-Corti et al, 2005
  14. Sugiyama T, et al 2010
  15. Takano 2002
  16. Gidlöf-Gunnarsson & Öhrström, 2007
  17. Berman 2008
  18. Marselle et al 2014
  19. Bjerke et al, 2006
  20. Guite, Clark & Ackrill, 2006
  21. Herzog, Maguire & Nebel, 2003
  22. Amoly, 2014
  23. Taylor and Kuo 2001
  24. Hystad P, et al. 2014
  25. Dadvand et al. 2012
Peter Dingle

Dr Peter Dingle (PhD) has spent the past 30 years as a researcher, educator, author and advocate for a common sense approach to health and wellbeing. He has a PhD in the field of environmental toxicology and is not a medical doctor. He is Australia’s leading motivational health speaker and has 14 books in publication.

http://www.drdingle.com/

https://www.facebook.com/DrPeterDingle/

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