More than just a pretty plant?

Growing a dwarf banana in your home can help remove toxins from the air.

I guess I have always heard, and mostly disregarded, that having a few houseplants in your home helps clean the air. The idea of billions of plants and entire ecosystems cleaning the air for the planet makes sense but applying it to less than ten plants seemed a little far fetched. I never really checked the facts as I felt that if it was another reason to get people to grow plants, even if not entirely based in fact, then so much the better. When I came across a blog entitled ‘Best Air-Filtering House Plants According to NASA’ I was intrigued. A 25 year NASA study might be enough evidence to convince even the most hardened skeptic.

NASA were of course studying the use of plants in space to recycle air. The original work, done in the early 1980’s, indicated that the ability for spider plants to remove formaldehyde from a closed container was much higher than expected – reducing it to undetectable levels in 24 hours.  Control tests were done with just a pot of soil and no plant, amongst other things, and yes, just the soil helped a little too, but the plant made most of the difference. Further studies have been conducted on the most common toxins found in homes and different plants help to reduce all of them.

What are these toxins and how do they get into our homes? Which plants are best at filtering them? Toxins come from many modern building materials, carpets, plastics etc. and also from humans themselves. Most plants seem to help reduce levels of these toxins, leafy fast growing plants seem more effective than succulents though only common houseplants were tested.  For more extensive answers to both of these questions and a great growing guide to 50 plants that were tested check out the book ‘How to Grow Fresh Air’ by Dr. B. C. Wolverton from the Helen Fowler Library.

The evidence seems to suggest that having 3 or 4 plants in an area the size of an office cubicle will really help improve the air qualilty in that space.  My skeptisim was weakening, but I was wondering what happened to all these toxins. Do they stay in the plant? Do they hurt the plants? The overly simplified answer is that the plants take in the toxins through their leaves and move them down to their roots. Once they get there, microbes that live on and around the roots break them down into other substances. It turns out that once a plant has been exposed to toxins for a while its capacity to take in and remove them from the air actually increases.

Once again I am amazed at how the common plants we see every day are living science fiction style secret lives of which we are often completely unaware. I have even more appreciation and respect for my house plants, which until now, I was growing for entirely aestheic purposes.