We Need Nature for Our Physical and Mental Well-being

我最近看了一套關於西伯利亞牧鹿人的紀錄片，他們在北極的氣候環境中，引領著馴鹿走過艱辛漫長的行程，晚上都在嚴寒的野外露宿，最後來到一個小鎮。鎮上的小房子麻雀雖小、五臟俱全，舒適的臥室、浴室和電視機等設施一樣不缺。節目主持人問牧鹿人為什麼不就留在鎮上？其中一位牧鹿人答道：「居住在四面圍牆的環境，和在牢獄中服刑無異。」

答得真妙！這答案與我打算在《明周》專欄中所寫的，關於人們應當體驗大自然的想法實在非常吻合。我不是說所有香港人都應該在極地環境中展開放牧生活，而是想指出牧鹿人所說的與我的看法不謀而合：所有人都需要大自然，在一個完全城市化的環境中生活，就是讓心靈活在鐵窗之間。

我在此中的分享，部份源自本身經驗：當我在陡峭的山徑間遠足、沐浴於天然景致中、專注於捕捉蝴蝶與雀鳥的蹤影時，城市給我的憂慮似乎一掃而空。也有研究報告指出，接觸大自然有助我們保持身心健康。近期由精神健康月籌委會工作小組進行的調查指出，有三分之一的受訪港人精神健康指數偏低，這可能源自城市生活的壓力，顯示我們有需要正視身心健康的問題。

為了撰寫這個專欄，我在網上查閱了很多有關健康與接觸大自然環境的資料。除了找到遠足一類戶外活動有益身體的資料外，我也看到有證據指出身處大自然中，甚至只是在樹木之間和看到樹木，本身已有不少益處。一項評估人造與天然環境對健康所起作用的研究便得到以下結論：「天然環境可能對身心健康有著直接和正面的影響。」

本年較早時，加拿大研究員報告了人們在大自然中散步後，運作記憶表現提升約16%。蘇格蘭的另一項調查發現，任何像公園散步以至在樹林中跑步的活動，對於患有抑鬱及焦慮人士均能發揮正面作用。此外，大自然為人們精神健康帶來的正面效果，較健身室高出50%。

格拉斯哥大學的Richard Mitchell教授表示：「就我們已知資料而言，調查結果言之成理。大腦喜歡大自然的環境，所以身在大自然時便會自行壓抑本身的壓力反應。在種有大量草木的地方有助我們寧神靜心。」

我知道香港不少地方好像與大自然風馬牛不相及，但事實卻非如此。身處香港，我們很容易就可到達香港島和九龍北面的郊野公園。那麼，為什麼港人在閒暇時仍愛留在擠迫的市區？

現代生活中五光十色，這裡有購物商場的吸引力，網上世界更有線上遊戲和「聊天」等科技誘惑。大自然更令太多人望而生畏：我便聽說過香港的孩子害怕坐在草地上、年輕人看到蝴蝶會感到驚恐。我試過邀請朋友結伴遠足而遭婉拒，她的原因是：「髒死了」。

髒！草和樹下沒錯都是泥土，但試想一下，在清潔明亮的商場中，當有人咳嗽和打噴嚏時，訪客不是馬上就吸入他們的病菌嗎？在2003年沙士肆虐 期間，很多香港人就是這麼想，所以商場變得不受歡迎，人們轉投青山綠水的懷抱。

爭相前往郊野公園的人群，很快便發現部份港人早已知道的事情：郊外地方並不可怕，香港身處精彩有趣的天然環境，有很多活動等待我們發掘，例如散步、拍攝風景和野生動物，還有攀越溪澗、獨木舟、攀石和滑翔等。

沙士其中一個留給我們的改變，肯定是市民較以前多參與戶外活動。但香港的萬「誘」引力絲毫不減，市民精神健康指數偏低，部份反映了大腦並不喜歡長期活在石屎森林之中。

衷心希望你是其中一位喜歡定期前往郊野的香港人，且不時會在市內的公園和綠色地帶中享受閒適。假如你還未開始，不如試試出外作個小冒險，看看有沒有吸引你的活動，我相信這個發掘過程最終會為你帶來長遠的好處。你很容易便會遇上樂意幫助你的人、結交新的朋友。不要只參加走馬看花的本地團，大可嘗試隨心而行、慢慢享受。

如果你走出去之後變得嚮往山巒翠綠，不如也一同參與保育工作、幫助勸告城市規劃的官員，我們不需要更多的石屎工程。大自然不單包括保護動植物，它對我們的身心也具有莫大禆益，更是社會長遠健康不可或缺的部份。

From an article in the Atlantic:

When the U.S. Forest Service looked at mortality rates in counties affected by the emerald ash borer, they found increased mortality rates. Specifically, more people were dying of cardiovascular and lower respiratory tract illness -- the first and third most common causes of death in the U.S. As the infestation took over in each of these places, the connection to poor health strengthened.
The "relationship between trees and human health," as they put it, is convincingly strong. They controlled for as many other demographic factors as possible. And yet, they are unable to satisfactorily explain why this might be so.

...
In a literal sense, of course, the absence of trees would mean the near absence of oxygen -- on the most basic level, we cannot survive without them. We know, too, that trees act as a natural filter, cleaning the air from pollutants, with measurable effects in urban areas. The Forest Service put a 3.8 billion dollar value on the air pollution annually removed by urban trees. InWashington D.C., trees remove nitrogen dioxide to an extent equivalent to taking 274,000 cars off the traffic-packed beltway, saving an estimated $51 million in annual pollution-related health care costs.

©Science
But a line of modern thought suggests that trees and other elements of natural environments might affect our health in more nuanced ways as well. Roger Ulrich demonstrated the power of having a connection with nature, however tenous, in his classic 1984 study with patients recovering from gall bladder removal surgery in a suburban Pennsylvania hospital. He manipulated the view from the convalescents' windows so that half were able to gaze at nature while the others saw only a brick wall. Those with trees outside their window recovered faster, and requested fewer pain medications, than those with a "built" view. They even had slightly fewer surgical complications.

...

there is something fascinatingly mysterious about the entanglement of our health with that of nature. The suspicion that this may be so, of course, is seen well outside of the scientific literature on the topic. Maurice Sendak knew it, as he spoke of his appreciation for the trees seen from his window in the final months of his life. And Henry David Thoreau, writing in The Atlantic in June 1862, said, "I think that I cannot preserve my health and spirits, unless I spend four hours a day at least -- and it is commonly more than that -- sauntering through the woods and over the hills and fields, absolutely free from all worldly engagements."

From the European Centre for the Environment and Human Health:

Our analyses suggest that people are happier when living in urban areas with greater amounts of green space. Compared to instances when they live in areas with less green space they show significantly lower mental distress (GHQ scores) and significantly higher wellbeing (life satisfaction).

The analysis also made it possible to compare the beneficial effects of green space with other factors which influence wellbeing. In comparative terms, living in an area with higher levels of green space was associated with improvements in our wellbeing indicators roughly equal to a third of that gained from being married, or a tenth as large as being employed vs. unemployed.

These effects emerge controlling for other differences at the different time points such as income, employment status, marital status, health, housing type and local area level variables, such as crime rates.

Urbanisation is considered a potential threat to mental health and wellbeing and although effects at the individual level are small, this study demonstrates that the potential benefit at a population level should be an important consideration in policies aiming to protect and promote urban green spaces for wellbeing.

from the University of Queensland:

Australians will be happier, safer and healthier if they look after the nature spots in their cities, according to new research led by The University of Queensland.

The research was led by Dr Richard Fuller from UQ's School of Biological Sciences and the National Environmental Research Program's (NERP) Environmental Decisions Hub, an Australian Government research hub hosted by UQ.

Dr Fuller said the research showed that having nature nearby can boost people's health, improve their ability to think, and help lower violence and aggression in the community.

“Conserving nature in cities, such as restoring habitats or setting up reserves can be expensive relative to conservation actions outside cities,” Dr Fuller said.

“This often raises the question of whether we should invest in keeping biodiversity within our urban areas.

“The answer is yes, as scientific studies around the world now show that experiences of nature provide important benefits to many aspects of our lives, including our mental and physical health, social relationships and even our spiritual wellbeing.”

One study that compared the effects of exercising in a green space and an urban environment revealed that stress was reduced after exercise in forest or parks but not in built-up areas. Another study showed that children who participated in gardening or who visited parks had improved self-esteem and mental wellbeing.

Spending time in nature can also help sick people recover faster, Dr Fuller said.

“Patients in rooms with a view of trees spend less time in hospitals, require fewer strong painkillers and have fewer postsurgical complications than those whose rooms overlook a brick wall.

“Nature can also lower death rates. Various studies in the UK and Netherlands show that people living near green spaces have lower disease loads and mortality rates.”

As well as physical and mental health benefits, the restorative properties of nature can improve a person's ability to tackle mentally challenging tasks, the studies showed.

“We constantly direct our attention towards avoiding hazards and coping with noise and sights in busy urban environments,” Dr Fuller said.

“This requires sustained effort and can lead to mental fatigue, resulting in reduced ability to concentrate.

“A study shows that when asked to repeat a sequence of numbers in reverse order, students who previously walked through a busy city street performed poorly compared to those who had walked through a tree-lined arboretum.”

Another study that tested people's ability to proofread reveals that those who spent their vacation in the wilderness made few mistakes, whereas the performance of those who spent their holidays elsewhere was poorer.

The benefits of living close to nature also extend to wider society. In Chicago, violence and aggression were significantly lower in buildings with more surrounding vegetation, Dr Fuller said.

In addition, having shared green spaces in urban areas encouraged social interaction and fostered empowerment. People who participated in community conservation projects often benefited from the social support they encounter there, he said.

“While we aren't sure which aspects of nature deliver these benefits – whether it's particular types of garden, trees or animals – there is mounting evidence that having green spaces close to us has a positive impact on our lives,” Dr Fuller said.

“This is a win-win situation for conservation and society - so we should hold on to our green spaces instead of clearing them for development.”

Dr Fuller says Australians could plant more trees and shrubs in their backyards to encourage biodiversity.

“It's important to have lots of vegetation where possible, including denser thickets, tall trees, low-growing shrubs and scraggly grass where birds and insects abound,” he said.

“In the meantime, spend more time outdoors, especially with your children. A nationwide survey in US shows that growing up in natural environments has a strong influence on positive environmental attitudes in adult life, and they are more likely to appreciate and support conservation in adulthood.”

The review, What are the benefits of interacting with nature? by Lucy E. Keniger, Kevin J. Gaston, Katherine N. Irvine and Richard A. Fuller is published in the International Journal of Environmental Research and Public Health. The paper is freely downloadable from: http://www.mdpi.com/1660-4601/10/3/913/pdf

The Australian Government funds the National Environmental Research Program (NERP) to inform evidence-based policy and sustainable management of the Australian environment.

From PBS:

The trees died first. One hundred million of them in the eastern and midwestern United States. The culprit: the emerald ash borer, a beetle that entered the U.S. through Detroit in 2002 and quickly spread to Iowa, New York, Virginia and nearly every state between. The bug attacks all 22 species of North American ash and kills nearly every tree it infests.

Then came the humans. In the 15 states infected with the bug starting, an additional 15,000 people died from cardiovascular disease and 6,000 more from lower respiratory disease compared with uninfected areas of the country.

A team of researchers with the U.S. Forest Services looked at data from 1,296 counties, accounted for the influence of other variables -- things like income, race, and education -- and came to a simple conclusion: Having fewer trees around may be bad for your health.

From Nat Geographic interview with Richard Louv:

If you look at a new body of research on depression, ADD, physical health, child obesity, and the epidemic of inactivity, nature is a good antidote to all of that. I didn't coin it, but I like the phrase "sitting is the new smoking," because new evidence shows that sitting long hours every day can have serious health risks similar to those caused by smoking.

Researchers at the University of Illinois are investigating whether time in the woods could be used to supplement treatment of ADD. A study at the University of Kansas found that young people who backpacked for three days showed higher creativity and cognitive abilities. People in hospitals who can see a natural landscape have been shown to get better faster.

As an antidote, we need to figure out ways to increase nature time even as technology increases. It has to be a conscious decision.

Connecting With Nature Boosts Creativity and Health

Richard Louv explains how society can overcome nature-deficit disorder

from realfarmacy website:

here are two interesting pieces of research that give credence to the feeling that our bodies and souls are better off from gardening.
Researchers reported in the journal Neuroscience that contact with a soil bacteria called Mycobacterium vaccae triggers the release of serotonin in the brain. This type of serotonin acts on several different pathways including mood and learning. Lack of serotonin in the brains is related to depression.
...
it turns out that harvesting fruits and vegetables triggers the release of dopamine in the brain. It is speculated that this evolved over 200,000 years of humans harvesting food as hunter-gatherers. Dopamine is strongly correlated with reward-motivated behavior.

could it be that the look and the layout of our cities is actually bad for our health?

A new report from the Royal Institute of British Architects (RIBA) sets out to prove just that. Comparing rates of physical activity, childhood obesity and diabetes in England’s nine most populous cities, RIBA have found a clear correlation between the amount of green space, density of housing in urban areas, and the overall health of the local population. 
...
estimates suggest that the risk of heart disease, stroke and diabetes could be cut by 50 per cent if people were to meet physical activity targets
,,,
Architects and urban designers could play a key role in “ mitigating the impact of a lack of green space and creating environments to support walking,” the report states.

Their practical recommendations include the creation of attractive, safe walking routes between green spaces, to encourage people to travel around the city by foot. Parks and recreations grounds themselves can be made more attractive as places to walk, run and play through simple measures such as improving walkways, letting in light by lowering any high walls or heavy vegetation and installing more bins and benches.

3. Spend time in nature. Daniel Goleman, author of Focus: The Hidden Power of Excellence, suggests spending time in nature to help us reset our attention span and relax our minds.

One experiment he mentions tested how relaxed people were when taking a walk down a city street versus in a quiet park. The study found that the level of attention needed to navigate a busy city street is high enough that the walk doesn’t let the brain relax enough to reset our focus levels:

Unlike natural environments, urban environments are filled with stimulation that captures attention dramatically and additionally requires directed attention (e.g., to avoid being hit by a car), making them less restorative.

Spending time in nature, however, allows your mind to fully relax and unwind and helps you focus longer when you return to work. Plus, other research has found that for students, motivation to learn is higher when they are outside instead of in a classroom.

5 Scientifically Proven Ways to Work Smarter, Not Harder

"A nice long hike, sans technology, can reduce mental fatigue, soothe the mind, and boost creative thinking."

http://www.collective-evolution.com/2016/04/08/doctors-explain-how-hikin...

Outdoor exercise delivers an estimated £2.2bn of health benefits to adults in England each year, a study suggests.
Scientists calculated that more than eight million people each week took at least 30 minutes of "green exercise".
They hope the results highlight how encouraging more people to use parks will help reverse the trend of rising obesity levels across the UK.

http://www.bbc.com/news/science-environment-37403915

Research indicates that motivating people to care takes more than just reciting facts and making doomsday predictions. Instead, it requires promoting compassionate concern for our natural world, which comes from early contact with nature, empathy for our fellow creatures, and a sense of wonder and fascination.

Specifically, scientists are starting to uncover how to encourage that compassionate concern in children, so that it will translate into pro-environmental behavior down the road

http://www.yesmagazine.org/planet/how-to-raise-an-environmentalist