 For perhaps 99.99% of our time on Earth as a species, we've been living outdoors in the natural environment. Might there be a health benefit to turning now and again and surrounding ourselves with nature? That's a question urban planners have asked. I mean, are people living in greener areas healthier than people living in less green areas? Should we put in a park or another car park? In a greener environment, people report fewer symptoms of illness and a better perceived general and mental health than by a considerable amount. Assuming the link is cause and effect, 10% more green space leads to a decrease in the number of symptoms that is comparable with a decrease in age by 5 years. But that is a big assumption. I mean, still you could imagine some potential mechanisms of why it could be. I mean, it could mean less air pollution, and air pollution is no joke. It's the fifth leading cause of death on planet Earth, wiping out about 5 million people a year. Of course, our diet kills twice as many as killer risk factor number one. So it could be an anti-pollution effect, or maybe there's something special about experiencing green spaces beyond them just offering more opportunities to exercise. But that's probably the simplest explanation, natural settings simply promote health-enhancing behavior rather than having specific and direct benefits for health. It's harder to go jogging in the park when there is no park. Ironically, it seems that even when people have access to nature, they don't necessarily take advantage of it. And even if there was a link, instead of natural environments drawing out increased physical activity, maybe physically active individuals are just drawn to living where there's nature. But what I wanted to know is, apart from the promotion of physical activity, are there added benefits to health of mere exposure to natural environments? Now, certainly just exposure to sunlight can treat things like seasonal affective disorder and provide the sunshine vitamin, vitamin D, but are there other inherent benefits? You don't know until you put it to the test. Some of the studies are just silly, though. At first, I thought this was about academic achievement and vegetarianism, but no, vegetation. They found a correlation between non-forest vegetation and graduation rates for schools. Maybe the Ivy League Edge has all just caused the Ivy? Okay, but this study starts to make things more interesting. The view through a window may influence recovery from surgery. This suburban hospital, some patient rooms, looked out at trees and others just to a brick wall. And the surgical patients assigned to rooms with windows looking out on a natural scene had shorter post-operative hospitals, stays into fewer potent painkillers than similar patients in similar rooms, but with windows facing a brick wall. You can't chalk that up to a vitamin D effect. What could it be about just looking at trees? Maybe it's the vitamin G, just the color of green. I mean, we know how healthy it is to eat our greens. What about just looking at them? Researchers have people exercise while watching a video, simulating going through a natural color-green setting, the same video in black and white, or everything flipped to red. And no differences were noted, with the exception of the red just making people feel angry. The most interesting suggested mechanism I ran across was fractals. You know how the branches of a tree kind of the same shape of a tree themselves? Fractal patterns are found throughout nature. You can see a cascade of self-similar patterns over a range of magnifications. And hook people up to an EEG, and for some reason, our brain apparently seems to like them. Regardless of the mechanism, if you compile together all the controlled studies and using nature as a health promotion intervention, you tend to see mostly psychological benefits, whereas the findings related to physical outcomes were less consistent. The most common type of study outcome was self-reportive measures of different emotions, like what makes you feel better staring at a kiwifruit orchard, or staring at a building. Awkwardly described things, presumably to the language barrier, as a comparison of synthetic versus organic stimulation. Natural settings may make people more attentive, less sad, and when it comes to some objective measures, like blood pressure, no significant effect. So, you know, you ask people who exercise outdoors, and they say they feel great, suggesting that green exercise activities have the capacity to increase mood, focus, and energy, and within just like five minutes of being out there in the woods. Yet these studies tended not to be randomized trials. They just asked people who already sought out nature what they thought about nature, and so no wonder they like it, otherwise they wouldn't be out there. But hey, you know, nature-based interventions are low-cost, often free, in fact, and non-invasive, unless you count the mosquitoes. So if you want a natural high, I say go for them, whatever makes you happy. Though evidently not all green exercisers like trees, golfers just viewed them as obstacles.