People need plants. We learn from an early age that we need them to create oxygen and food. As it turns out, we also need them for healthy bodies, minds, and communities. Earlier this year a few of our employees went to a lecture organized by Keep Indianapolis Beautiful called "Green for People: The Essential Nature of Greenspace for Urban Residents". The speaker was Dr. Kuo, a professor and researcher at the University of Illinois in Urbana-Champaign. She is a pioneer in the field of human interactions with the environment and has produced an impressive body of work that sparked international interest in how nature impacts humans, especially in urban environments. Her presentation brought us the latest research on the subject and convinced us more than ever of the importance of high quality green space in cities. This will be part one of a two-part series on the research she presented. First we'll list the components of nature that can impact humans and then explore the biological and psychological impacts of these things. Next week we'll take a look about how all those impacts work together to create lives that are happier, healthier, and more socially connected.
Dr. Kuo began her lecture by talking about the actual components of nature that benefit humans - she calls the the active ingredients in the human-environment interaction. It's one thing to know that nature is good, but it's another thing to understand the mechanisms by which the natural world changes us. She listed seven active ingredients to focus on: clean air, chemicals called phytoncides, a microbe called Microbacterium vaccae (or M. vaccae for short), the diverse microbiome of the natural world, negative air ions, reduced heat island effect, and the simple sights and sounds of nature. Some of these may be familiar to you - others not so much, but we'll explain how each affects us physiologically and/or psychologically. If you want to learn more about any of these effects, simply click on the links to find helpful articles.
Let's start with the physiological responses to the active ingredients. Plants help provide clean air, and clean air improves lung health and lets us avoid pollutants. Phytoncides are amazing airborne molecules released by plants that boost immune activity by increasing the number of natural killer cells in the bloodstream. Natural killer cells fight viral infections and are part of the body's defense against cancer. Scientists are learning more and more every day about microbiomes - the diverse mixes of bacteria and other micro-organisms that are found everywhere. The microbiomes found in nature can help improve immune system function and overall health in too many ways to specify in this post. Next up is the heat island effect. Urban areas can be up to 20 degrees warmer than nearby suburban areas because concrete, asphalt, and glass reflect heat and because plants cool the air when water evaporates from their leaves (evapotranspiration) and when they provide shade. Using greenspace to reduce city temperatures can reduce heat stroke, heat exhaustion, and other negative health effects of excessive heat.
Now we move to the psychological effects of nature. M. vaccae, the soil microbe, has been clinically shown to reduce symptoms of depression. Negative air ions, which are released by running water, can also reduce depression (Dr. Kuo reported only on scientifically measurable findings - you can also find all kinds of other claims about negative air ions that may or may not be real). Reducing the heat island effect can also reduce the irritability and anger associated with heat waves. The sights and sounds of nature reduce adrenaline and recharge our ability to think and focus, causing people to be more calm and less stressed. In fact, simply looking at images of nature can cause people to enter into a physically restorative state of deep calm that can be found in few other ways (hence the lovely pictures we've added to this post - all of which are from urban settings).
You can probably already start to see how connecting these dots (and adding others) draw a picture of a better life with more greenery. Read part 2 to see how we can piece these effects together and look at the big picture of how a green life is a good life, and a green community is a good community.