CSB #7 - Does exposure to trees and plants have health benefits?

At this time of year, allergies and AC keep many people indoors.
But for those who spend time outside in nature might be experiencing some surprising health benefits.

In a series of studies, scientists have found that when people spend a couple of hours in nature (parks, forests, some place with lots of trees), they experience increased immune function.


First off, stress level is reduced. However, it's not just that.

Scientists also found that phytoncides (chemicals in the air that plants emit to protect them from insects and rotting) are also beneficial to humans.

One of these studies was published in January. It took place in Japan.
280 people of good health were the test subjects.

One one day, some people were told to walk through a forest/area with lots of trees for a few areas. Actually, "Shinrin-yoku" or "forest bathing" had became a popular therapeutic practice in Japan.

The other people were instructed to walk through a city area.


On the second day, they traded places.

Scientists found that, "being among plants produced lower concentrations of cortisol, lower pulse rate, and lower blood pressure, among other things."
Cortisol - a steroid hormone produced by the adrenal cortex. It is released in response to stress. However, a high level of cortisol leads to many negative effects such as decrease in bone density & muscle tissue, higher blood pressure and lower immunity.


Numerous other studies have shown that being in forest surroundings seems to increase levels of white blood cells.


In one of these studies, men took 2 hour walks in a forest over two days. They had about a 50% increase in levels of white blood cells.


In another study, women spent time in forests and scientists found an increase in white blood cells in them that lasted about a week.

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I found this article really interesting because I spend a lot of time outdoors and I always felt better after spending some time outside.
I just assumed that being outside was good for me but I never had any evidence.


Citations -

ARTICLE: O'Connor, Anahad. "The Claim: Exposure to Plants and Parks Can Boost Immunity."
New York Times. N.p., 25 Apr. 2011. Web. 7 May 2011.
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PICTURE: http://www.ca.uky.edu/forestry/maehrbearky.php