© 2010 (text)
Sitting here working, with a vibrant fall wind blowing in my many open windows,reminded me of an article I recently read. The article touted house plants as a natural air purifier, which is appealing with the closed house season approaching; or for someone allergic to outdoor pollen. It cited a “recent” NASA study to back up the claim; and listed several plants, but didn’t indicate what each plant purified from the air, so I did my own research.
NASA did complete a study on the viability of house plants to remove air borne particles. Scientists created a closed, synthetic environment, rigged to cause irritation to inhabitants. Irritation they hoped that the introduction of certain plants would resolve. Two things, though: 1) the study was done in 1989; and 2) NASA’s study only tested and documented the listed houseplants for effective absorption of three chemicals, formaldehyde, trichloroethylene and benzene, from synthetic materials.
There was some indication that the negative ions emitted by plants might reduce mold spores and other bacteria; although, the scientists did no actual study or measurements on this theory. So, clearly house plants cannot sub for electronic air purifiers. (More on those in a later article.)
It was heartening to discover that this NASA report has not been negated; and was performed over a two-year period. The report clearly demonstrated that specific plants improve indoor air quality—from the above three chemicals anyway.
According to NASA, the following plants filter these contaminants from the air.
FORMALDEHYDE. The bad news is that this chemical exists in almost every household. The good news:
the dracaena, warneckii, peace lily, green spider plant, philodendron, bamboo palm, and mother-in-law tongue provide an effective defense against formaldehyde fumes. Peace lilies, bamboo palms, mother-in-law tongue and Chinese evergreens topped the most effective list. In an earlier, preliminary 1982 NASA study, golden pothos also proved highly effective.
It’s probably no surprise to learn that formaldehyde lurks in building materials such as insulation and new carpet, as well as pressed wood, upholstery, natural gas and some cleaning products. You probably didn’t know this chemical exists in paper grocery bags, paper towels, and waxed paper. And, are you ready for this? Permanent press clothes. Cigarettes may also contain formaldehyde.
This chemical causes irritation to eyes, nose and throat. However, chronic exposure can affect the upper respiratory tract and bring on headaches. Its most serious gifts, at high levels, are asthma and throat cancer.
BENZEN. With chronic exposure, benzene can, even at low levels, irritate eyes and skin; and bring on nervousness, blood diseases such as anemia, headaches, dermatitis, loss of appetite, and drowsiness—to name a few. Inhalation of high levels could put you in the hospital or cause an expensive doctor visit at the least. The NASA study cited evidence of benzene as a potential contributing factor in leukemia and lymphatic and respiratory disease. Paints, oils, rubber, detergents, dyes and plastics contain benzene.
The peace lily, bamboo palm and mother-in-laws tongue also combat benzene air contaminants. Other plants that remove air borne benzene include: English ivy, chrysanthemums, and gerbera daisies (pictured in next section). English Ivy, golden pothos and peace lily rated as the top three in the NASA study, with the bamboo palm as a contender.
TRICHLOROETHYLENE. This chemical also shares, with the other two, the peace lily, bamboo palm and gerbera daisy as combatants; with the Gerbera daisy, peace lily, and mother-in-law tongue at the top of the NASA list. And, in the middle of the pack, the bamboo palm.
The NASA study cited a National Cancer Institute report of a high incidence of liver carcinomas caused by trichloroethylene. This chemical is found in household items such as dry cleaning solvents, paint, varnishes, adhesive and ink.
Plants would seem to be particularly good in newly constructed homes, where builders use lots of synthetic materials and all of the chemicals are fresh. Experts seem to be divided on how long said chemicals remain in such items. In addition to plants and electronic air purifiers, you might consider installing green building products (especially paint) and green furnishings, using non- toxic cleaners, avoiding artificial air fresheners, and installing HEPA air filters for the A/C, etc. The NASA team did agree that the plant roots absorb more of the chemicals if surrounded by activated carbon. The carbon retains the contaminants until the plant takes them in.
Do also keep in mind that you’ll need several plants for effective absorption of formaldehyde, benzene and trichloroethylene. For total effectiveness, some experts recommend a six-inch plant for every one hundred square feet. If you have even a 1,500 square foot home, that’s fifteen plants, which would mean putting a plant in every room (including bathrooms) and doubling/tripling up in others. If you love taking care of plants or have some real problems with these chemicals, then that would be worthwhile.
I don’t want that many dead plants on my conscious. So, it seems to me that concentrating the plants in living areas where you feel contaminants likely lurk can be beneficial. For instance, there’s likely formaldehyde in your living room/kitchen area, so arrange two or three plants there.
Also, buy those plants that absorb all three contaminants. The peace lily, Gerber daisy or bamboo palm fits the bill.
Even with only one or two, you still get a benefit and the added bonus of releasing oxygen into the air. Although, if you have, or use, a lot of chemicals in your household (i.e., gas appliances, chemical cleaning materials, stains and varnishes, some upholstery, adhesives, etc.), you’d do well to visit your nursery and pick up a few plants.
New construction or not, remember that whatever the plant pulls in, it releases as oxygen and increases the humidity.
The NASA study also demonstrated that continuous exposure from formaldehyde, benzene, and trichloroethylene fumes to the plants you’ve selected improves the absorption rate, whether it’s two or twenty plants. Per the scientists, the plants essentially adapt and begin to utilize the chemicals as a food source. So, I wouldn’t recommend using any of these plants in your dinner. And bonus; no worries about your plants croaking from the chemicals.
One note of warning: damp potting soil can encourage growth of mold. Experts recommend covering the soil with washed small gravel if you go with a large number of plants. Reducing the exposed damp soil retards the growth of mold.
For people like me, who have killed many a plant, Better Homes and Gardens‘ web site (http://www.bhg.com/gardening/plant-dictionary/annual/gerbera-daisy/) is chocked with useful information on plant care and much, much more. After all, the plants cannot help you if they are dead or dying. You’ll also find the site helpful to aid you in choosing your plants. For instance, the pothos plant can grow to over 8’ and has some color in its leaves for those who want more than green, but don’t want the care flowering plants require. The Pothos doesn’t mind little light or your failure to water often.
Plants are a simple, cost effective way to combat especially lethal contaminants that plague our living space. However, beautiful and beneficial as plants can be, they still do not necessarily address many other worrisome contaminants in our homes. These include: animal and human hair, dust mites, mold, smoke, skin cells, pollen, germs from coughs and sneezes, and lots of other bacteria. This is where the electronic air purifiers—HEPA or Ionic air cleaners—triumph. Keep in mind that just as the plants can’t combat mold, etc., the electronic cleaners do not remove gaseous contaminants (i.e. Formaldehyde) from the air.
One final codicil: don’t buy the plants or the machines thinking either will eliminate health problems such as asthma. These systems and the plants reduce, but don’t eliminate, airborne allergens/ contaminants. The air cleaners won’t screen viruses either. Both the natural and electronic air purifiers can help, but none are a cure.
And darn it, you still have to dust!
© 2010 (text)