Monday, June 9, 2014

Air Cleaning Plants from the NASA study - My New Obsession

As I mentioned a few weeks ago, I'm taking a little break from the Aerogardening and waiting anxiously for the Niwa. In the interim, I figured I'd go back to my roots (no pun intended), leave (no pun intended) herb gardening for a while and branch (no pun intended) off into a new kind of indoor garden.

Specifically, my new obsession is buying houseplants that clean the air.

Now hopefully everyone remembers from elementary school how photosynthesis works. Plants take in carbon dioxide and release oxygen. As luck would have it, humans breathe in oxygen and expel carbon dioxide. We live in a world where we've chopped down trees and put up office buildings in their place. Not that there's a lack of oxygen, but one nice thing about having plants around is that you get your own, personal supply of free, unlimited oxygen as long as they're around.

We live in a world that's filled with pollution. Sure, things like the Clean Air Act have helped with the worst offenders, but when you think about it, we're still surrounded by chemicals. Walls in our offices and homes are painted, furniture is polished, smokers who have been banned from smoking in public places outside have been chased indoors (we call our next-door neighbor "Smokey the Bear"), all kind of chemicals are used in manufacturing and energy production and it all fills the air.

But one thing that's cool about plants is that they take in more than just oxygen. They also take in other pollutants that are harmful to humans, including benzene (a common solvent found in gasoline, inks, oils, paints, plastics, and rubber, known to irritate the skin and eyes and even cause chromosomal mutations and leukemia), formaldehyde (found in foam insulation, grocery bags, wrinkle resistant clothes, cigarette smoke, pressed-wood products, floor adhesives), and trichloroethylene (found in inks, paints, varnishes, adhesives). All of these chemicals are all around us in our homes and offices, and all of them can be harmful to health. But with plants, the more they breathe in, the less you do.

There was a NASA study done in Mississippi in 1989 called "A Study of Interior Landscape Plants for Indoor Air Pollution Abatement" that studied different kinds of common, household plants and identified the ones that were most effective in cleaning the air. You'll find Web sites like this and this with lists of these plants, but as your friendly neighborhood Indoor Gardener, I thought I'd go a step further, go out and purchase these plants for myself, and write a few posts on the best houseplants for air purification.

So here's what I'll be doing for the next few weeks. I'm going into my local K-Mart that always has a stock of common household plants, and I'll be buying one from the NASA list every couple of weeks and sharing with you photos and stuff I'm able to find out about the best air cleaner plants. My goal is over the next few months to have collected all of these plants and put them in the sunny window in my office or living room.

If you're interested in the full NASA list, here it is. The reason you might see different lists on different Web sites is that there were a couple different studies in 1989, each which used different plants. This is a complete list I pulled from NASA's final report from their original experiments.
  1. Golden Pothos (epipremnum or scindapsus aureus)
  2. Warneckei (dracaena deremensis "warneckei")
  3. Marginata (dracaena marginata)
  4. Mass Cane/Corn Cane (dracaena massangeana)
  5. English Ivy (hedera helix)
  6. Peace Lily (spathyphyllum "mauna loa")
  7. Bamboo Palm (chamaedorea seifritzii)
  8. Chinese Evergreen (aglaonema modestum)
  9. Gerbera Daisy (gerbera jamesonii)
  10. Janet Craig (dracaena deremensis "janet craig")
  11. Mother-in-Law's Tongue (sansevieria laurentii)
  12. Pot Mum (chrysanthemum morifolium)
  13. Ficus (ficus benjamina)
  14. Heart Leaf Philodendron (philodendron oxycardium)
  15. Elephant Ear Philodendron (philodendron domesticum)
  16. Spider Plant (chlorophytum elatum)
If you read the original paper from NASA, the experiment went something like this. For each test, they planted two identical, healthy individual specimens of each plant into two separate and sealed plexiglass chambers. They filled the chambers with a mixture of gases like benzene and thichloroethylene (TCE). They took a sample of the gas immediately, and then left the plants overnight in the sealed chambers. 24 hours later, they tested it again. They opened the chambers and removed the plants. The foliage was removed from one of these two plants. 

Remarkably, all of the plants in the study showed dramatic reductions of formaldehyde, benzene, and trichloroethylene.

Eight years in 1997, principal NASA investigator B.C. Wolverton, who published the original paper, ended up writing a book called How to Grow Fresh Air: 50 House Plants that Purify Your Home or Office featuring 50 houseplants that clean the air.

20 years after this original study, researcher Kamal Meattle presented a TED Talk called "How to Grow Fresh Air" that pointed out the three plants he determined were most important: The Areca Palm (chrysalidocarpus lutescens), the Mother-in-Law's Tongue (sansavieria trifasciata), and the Golden Pothos (epipremnum or scindapsus aureus).


 First plant coming up in my next post--the Golden Pothos.

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