Green prescriptions

A healthy environment is central to human health. It provides us with clean air, water, food and a stable environment. As we become increasingly urbanised, it is easy to forget how much we are part of the natural world. We need to respect it more if we are to survive.

Nature can provide therapeutic benefits that can help our patients. The most well documented benefits have been in mental health. Spending time in nature has been shown to reduce stress, improve mood, reduce depression and anxiety and help children with learning and concentration. The effects are as good as many other therapies. “Green prescriptions” should be used as a therapeutic tool. Dose responses for both intensity and duration show large benefits from even short engagements.

Apart from the psychological benefits, spending time in nature can reduce blood pressure and heart rate, improve sleep characteristics and pain scores and enhance rehabilitation for those with drug dependency issues and post-chemotherapy care.

Among the most interesting effects is that on the immune system. Natural killer T cells are important in cancer therapy and have been shown to increase in number after time spent in nature in some situations. This would suggest a beneficial effect on cancer prevention. There is certainly evidence that landscape biodiversity correlates positively with respiratory health in Australia. This maybe mediated via the microbiome.

As well as the importance of our external environment, the importance of our internal ecosystem is gaining greater attention. The microbiome comprises the organisms that co-exist in and on our bodies. These exert an effect on our health including our mental health and immune function. The microbiome has developed over thousands of years and has been derived from our interaction with nature. This interaction has dramatically changed in the last 100 years, with decreasing exposure to natural environments. We may be losing the so called, “old friends” mechanism. “Old friends” are harmless microbials with which humans have evolved. This loss may result in a loss of immune-tolerance. Failure of immune-regulation is a likely contributor to the development of autoimmune disease. For example, we are seeing an increase in autoimmune diseases such as ulcerative colitis which, in some parts of the world, is now as common as 1 in 200 people. It follows that exposure to natural environments may be protective against development of these diseases.

The increase in the use of antibiotics in humans and animals, as well as the huge increase in the number of chemicals including herbicides and pesticides, is likely to play a part in the change to our microbiome. Since the 1950s there have been over 140,000 new chemicals and pesticides manufactured. Of the 5000 most common, less than half have been tested for human safety and toxicity. The use of these chemicals have damaged the biodiversity of microbes in the soil, on plants and in the water and probably affected our microbiome.

One of the best ways to protect the forest as well as helping our patients is to recognise its therapeutic potential. Shinrin Yoku or “forest bathing” is a therapy that we could be utilising in Australia. This is the practice of immersing oneself in nature by mindfully using all five senses. One solution is to prescribe time in a “green space”. This can be as simple as a 30-minute walk or it could be a more structured therapeutic intervention.

Doctors can also prescribe a greener working environment. “Greening” the workspace improves the health of workers, improves productivity and job satisfaction. As we do with not smoking and healthy eating, doctors can model a healthy workplace by having indoor plants, natural light, good ventilation and getting outside into a park or garden for a walk at lunchtime or perhaps by ditching the car and walking or cycling to work.

PROTECTING THE FUTURE

We are now more dependant than ever on having a clean and protected natural environment. Unfortunately, our natural environment is being destroyed more rapidly than ever. Until the recent change of government in Queensland, that state was amongst the worst 10 areas in the world for deforestation. Deforestation continues at an unacceptable rate. In New South Wales there has been an 800% increase in deforestation over the last three years.

Forests are important for our immediate health, providing clean air, reduction in air pollution, cooling, and psychological benefits. They are also essential for the health of the planet and consequently our long term survival. They provide moisture in the atmosphere for rain, stabilisation of soils, and removal of carbon dioxide from the atmosphere. At a time of severe drought, protecting forests is more important than ever. Forests also filter water providing us with free services such clean drinking water from protected catchments – services which would otherwise require costly engineering solutions.

In 2009, The Lancet recognised that “Climate change is the biggest health threat of the 21st century”. We have been seeing the effects, such as extreme weather events, heatwaves, flooding and spread of infectious diseases over the last decade. The world needs desperately to decrease its carbon emissions and look at ways of sequestering carbon out of the atmosphere. Protecting existing forests is going to be critical to mitigate against these effects on our health. We also need to rehabilitate degraded and cleared land to improve the health of our rivers and other water systems.

Climate change has indirect effects on health, such as impacts on our food supply. There was a 20% decrease in food productivity from 2000/01 to 2014/15 in some parts of Australia. There are also economic losses. The cost of extreme weather events globally in 2016 was $US129b. QBE recently recorded a $1.6b loss to due extreme weather events.
In 2017, nearly 10% of Australia’s carbon emissions were due to forest being converted to other uses (ie deforestation). Protecting forests is one of the easiest steps to reduce our emissions.

However, governments also need to act. There should be an immediate worldwide halt to all old growth forest logging. We need to see an increase of “greening” in the urban environment. This will help to mitigate against climate change but will also give immediate benefits to decrease the “urban heat effect” related to heat-absorbing surfaces. Governments need to give incentives to farmers to protect their trees and soils as well as dramatically expand programmes to sequester carbon from the atmosphere. This will help protect against drought but is also likely to help with the mental health of our farmers and Indigenous people.
So what are we waiting for?

Article contributed by Dr John Van Der Kallen, Rheumatologist and Chair of NSW Doctors for the Environment Australia (DEA). Article references available upon request to the editor – andrea.cornish@amansw.com.au