In the war against air pollution, plants are a natural weapon. They are surprisingly effective at removing many toxic substances from the air. Research has shown that some plants are much better than others at this task, and just how they accomplish air purification is fascinating.
The Beginning of Plant Purification Research
Bill Wolverton, while working as an environmental scientist with the US Navy, discovered that swamp plants were actually cleansing the air of a toxic substance called Agent Orange. Agent Orange is the name for a specific mix of herbicides that were used to kill the leaves of trees that US enemies were hiding under during the Vietnam war, thus exposing them. However, the Agent Orange pollution that Bill Wolverton had experience with was actually from government testing near Eglin Air Force Base.
After discovering that swamp plants were purifying the air, Wolverton changed positions and became employed at NASA’s Stennis Space Center. Here the Space Agency funded his research in a program called Stennis’ Environmental Assurance Program, which allowed him to study the environment's natural ability to clean itself. Three goals were outlined in this program: 1. To naturally clean the Stennis Space Center of chemical wastes 2. To supply NASA with information about the ability of plants to support a closed environment ecosystem (i.e. the Space Station) 3. To make the research available to the American public. Wolverton's first contribution under his new title was to finish up some work with the military, where he actually replaced the traditional septic system with water hyacinths- a system that is still in use today.
Finding a Solution for Sick Building Syndrome
It seems that the Skylab Space Station sorely needed Wolverton's help, as 107 VOC's (volatile organic compounds) were found shut up in the Station in 1973. The synthetic materials used to construct the Skylab were giving off poisonous chemical gasses such as formaldehyde, benzene, and trichloroethylene. These substances were known to be irritants and possible carcinogens. Furthermore, due to the energy crises at about the same time, many builders were constructing houses and other buildings more energy efficient (i.e. airtight).
These airtight dwellings that were giving off toxic gasses -which had no place to escape- were making people sick. When people are exposed to buildings such as these and develop troubling symptoms, it is referred to as Sick Building Syndrome. Sick Building Syndrome can cause a varied array of troubling symptoms, which can include respiratory distress, burning mucus membranes, headache, flu like symptoms, sensitivity, nausea, etc.
A Breakthrough Solution for Indoor Air Pollution
Wolverton did not believe that people should necessarily change building materials or the way they built structures- he believed they should simply take along a little something extra. As he stated in 1989 “If man is to move into closed environments, on Earth or in space, he must take along nature’s life support system.” The life support system he was referring to was plants.
NASA's first experiment to test Wolverton's hypothesis was with a dwelling called Biohome. Biohome was a dwelling that was constructed for testing purposes. It was large enough to be occupied by one person and many plants. All who entered Biohome before the plants were placed within complained of symptoms associated with Sick Building Syndrome. However, once the plants were added to the indoor environment, an analysis of the air showed that most of the VOCs were gone, and all symptoms associated with Sick Building Syndrome subsided. The experiment was a success, and showed that plants do indeed dramatically improve air quality.
What Wolverton discovered about plants from his studies, he published in many technical papers and also in a consumer friendly book called to "How to Grow Fresh Air: 50 Houseplants That Purify Your Home or Office.” In this book Wolverton shared the fascinating method that plants use to purify the air. In his writings, he stated that plants release water vapor, which creates a pumping action, and that action pulls in contaminated air and deposits it around the roots. The contaminated air is then converted into food for the plant. Once the plant uses the toxic gasses for food, it lets off oxygen as its waste product, making the environment even more healthy for humans and animals.
Best Plant Choices to Improve Indoor Air Quality
Wolverton also spoke in his book about an additional research product that he conducted on several types of plants. Each plant was individually sealed in a plexiglass container, and the air within injected with specific toxins. Analysis on the the chamber air was conducted to see how well each type of plant performed in purifying the air of specific toxins. The Spider Plant (Philodendron) and the Golden Pothos were the best performing plants in removing formaldehyde, a common off gas of building materials. Flowering plants such as the Gerber Daisy and Chrysanthemums excelled at removing benzene , which is another common off gas from building materials.
To get the most air purification from indoor plants, they should be placed near a fan or in an area that is drafty. The more air that passes by a plant, the more it can pull in, thereby removing harmful substances. Another tip that Wolverton gives is to use carbon in the soil. The carbon will absorb the toxins and disable them.
Sources
- Sti.nasa.gov, "Plants Clean Air and Water for Indoor Environments", 7-23-2010
- Epa.gov, "Indoor Air Facts No. 4 (revised) Sick Building Syndrome", 7-23-2010
- Publichealth.va.gov, "Agent Orange", 7-23-2010
- Plant-care.com, "Indoor Plants – Clean Air", 7-23-2010
Angel Chavis - Angel Chavis lives in NC with her husband, daughter, and various pets. She is a Christian, wife, homeschool mom, writer, student, and ...
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