by BRIAN MINTER
January 12, 2000
Now that the lights, trees and decorations of the colourful festive season are put away, things may look just a little bleak inside our homes. Thank goodness for indoor plants! They have a unique way of making a house or apartment look like a home, but unfortunately, it is the worst time of year for indoor plants. Low light, poor humidity, and short days all combine to make it difficult for them. Certain varieties, however, seem to stand up better than others, and there is more good news. Many of these tougher plants also help clean the air inside our homes. It's no secret that humans would not be able to survive in this world without plants. Thanks to a research study directed by Dr. B. C. Wolverton of the National Aeronautics and Space Administration, more commonly known as NASA, we now have scientific proof that plants can remove many of the toxins from inside our homes and work areas.
NASA has obviously been concerned about man's ability to live in closed environments, both on earth and in space. Dr. Wolverton has been the principal investigator in a study on the use of plants to reduce air pollution in confined areas. Twenty common houseplants were tested for their ability to remove from interior environments three of the most commonly recognized pollutants: benzene, trichloroethylene and formaldehyde.
Benzene is a solvent commonly used in inks, oils, paints, plastics and rubber. It has long been known to irritate both the eyes and skin. There is also evidence that it may be a contributing factor in leukaemia.
Trichloroethylene is a commercial product used in printing inks, paints, lacquers, varnishes and adhesives. The American National Cancer Institute considers it a potent liver carcinogen. Formaldehyde is a chemical found in virtually all indoor environments. It's used in grocery bags, facial tissues, paper towels and particle board. Many common household cleaning agents contain formaldehyde, as do heating fuels such as natural gas. This chemical can irritate the mucous membranes of the eyes, nose and throat and can cause headaches and irritation to the upper respiratory tract.
The plants used in this study were common varieties. They included: Bamboo palm, Chinese Evergreen, Dracaena 'Janet Craig', Dracaena marginata, Dracaena warneckii, Dracaena massangeana, 'Mother-In-Law's Tongue', Peace Lily and Chrysanthemum. The testing was done according to strict scientific principles, taking into account all environmental factors right down to the micro-organisms in the soil. The plants were sealed in plexiglass containers for a twenty-four hour period while, under separate tests, each of the three chemicals was injected into the sealed chamber.
The results were very interesting. When it came to removing trichloroethylene, the Dracaenas, Peace Lilies, and Bamboo palms scored very well. Chrysanthemums were extremely effective in removing benzene, while the Draceanas, Bamboo palms, Peace Lilies and Mother-In-Law's Tongue did a fair job. As for formaldehyde, Bamboo palm did the best, followed by Dracaena 'Janet Craig'; Mother-In-Law's Tongue and all the rest came in quite a bit lower in the efficiency ratings.
Without going into hours of detailed analysis, I think there are some very significant findings here. Combinations of these plants inside our closed living areas can, as proven by scientific research, remove a significant percentage of the toxins which are very harmful to us. Refinements of this testing will lead to more specific results, but the message is certainly there. As a ball park figure, one plant per 100 square feet of living space can make a difference in removing three common toxic chemicals from our homes and offices.
This is not a pitch to get you to buy more plants, but rather some welcome news for those of you who care about the quality of your inside air space. I'm sure further testing will reveal more helpful plant varieties, but with the ones I have mentioned here, compliments of NASA's research, you're on the right track. For those of you with 'brown thumbs' and silk plants, you may want to get serious about indoor gardening. We've now got the proof ... it's good for you!