How does a green environment lead to better health?
Much research has already been done into the consequences of, for example, the use of pesticides in nature and the environment and its unpleasant consequences. Studies using positive variables to measure health variation are much fewer in number. 

An exception to tradition is provided by Dr. Qing Li. This researcher has spent years researching the influence of a wooded environment on our health. He demonstrated its positive influence on the so-called ‘ natural killer cells ‘ (NK cells), which are part of our (innate) immune system. *  Li suspects that the trees’ volatile aromatic substance, or phytoncides, play an important role in activating these specific cells. With his investigations he shows that relaxing in nature can lower blood pressure. Stress reactions become lighter and the immune system becomes more resilient. Staying in the woods improves energy levels, has a positive effect on creativity and increases concentration.  But it is not clear, he says, which factors in the forest activate human NK cells.

The immune system

According to Qing Li, ‘ forest bathing ‘ is not just a stroll in the forest, but a slow walk in the forest. “ Breathing deeply is very important and walking slowly,” he says. The doctor goes into the forest with groups of people and takes blood samples before and after the ‘ forest bathing ‘ to measure the activity of the NK cells, the
natural killer cells. These cells play a major role in our immune system and are referred to by him as the ‘ body police ‘ .
With his research he shows that the effects of forest bathing are visible in the activity of these NK cells for up to seven days. “The hypothesis is that if you take a walk in the forest once a month, you reduce the risk of cancer, because the activity of the NK cells is stimulated. So ‘ Forest Bathing’ works as preventive medicine, ” his film explains.

Dr. Qing Li’s research also shows that a long walk through the city has almost no effect on the activity of the NK cells. “ So it’s not about the physical activity of walking, but really about walking in nature,” he explains. Walking in a forest has the strongest effect, but walking in a city park is also possible. ” You have to do that every day and the more trees there are in the park, the greater the effect will be.”

* Natural killer cells or NK cells are large lymphocytes belonging to the innate immune system and which play a role in cell killing and secretion of cytokines used against pathogens