Houseplants for Pure Air

The world spends a lot of time worrying about air pollution caused by spewing factories, the burning of fossil fuels, and the release of chemicals from the use of equipment essential to modern living. You rarely read an article that concentrates on indoor pollution, yet most of us spend 80% to 90% of our time indoors.

Not only do we spend much time indoors but we spend that time in buildings that are almost hermetically sealed. Windows in office buildings and other public buildings are not made to open. Homes are insulated, air conditioned and every crack and crevice is sealed to conserve energy.

The EPA has found measureable levels of 107 cancer causing chemicals in buildings. At higher levels these chemicals result in what have been labeled “sick buildings”.  Whether exposure to these chemicals in low dosage will cause an increased incidence of cancer over long periods of time is unknown. It is known that residents or workers in these sick buildings who are exposed to volatile organic compounds (carbon containing compounds that vaporize) have exhibited a number of medical problems. While some people seem to be immune to low dosages of volatile organic compounds others are more sensitive. The more sensitive often have irritation of the eyes, nose, and throat.  In more extreme cases they may develop headaches, nausea and nerve damage.   Exposure to excessive amounts of ozone can result in are pulmonary edema, hemorrhage, inflammation, and diminished lung capacity.

Where do these compounds come from? They are in many common household cleaning products, varnishes, glues, waxes, disinfectants and cosmetics. Cigarette smoke, kerosene, gasoline and pesticides contain VOCs. Carpeting, drapes, wall board, wall coverings, finished furniture and upholstery can give off VOCs.  . Formaldehyde is used in the manufacture of foam insulation and particle board, as well as in many cleaning products.  Benzene is found in oils and paints. Trichloroethylene is used in paints, adhesives, inks, and varnishes.  Toluene is present in paint thinners, paint brush cleaners, nail polish, glues, inks and stain removers. It is also found in car exhaust and the smoke from cigarettes. Ozone is not a VOC but it is another problem compound given off by laser printers, copying machines and ultraviolet lights.

In the 1989 NASA conducted a study aimed at reducing volatile organic compounds in space craft. In 2009 Penn State conducted a survey on reducing indoor ozone levels. Both studies came up with the same answer……..houseplants. There is considerable controversy involving the NASA study conducted by Dr. B.C. Wolverton and even the researchers were of the opinion that it was not the foliage of the plants but the bacteria in the soil that produced the positive results. Still, it can be argued that the mini ecological system of plant, soil and bacteria were effective in removing VOCs from the air in controlled conditions. There is also concerns that these results would not be applicable to the much larger areas found in building. The original study can be read here It is a simple read for a scientific study.

The Penn State study tested snake plant, golden pothos and spider plant for removing ozone from a closed chamber into which a calculated quantity of ozone was injected. This study concluded that ozone levels were measurably lower in the chambers that contained plants than in the control chambers which did not. The researchers concluded that houseplants “could serve as a cost-effective tool in the developing world where expensive pollution mitigation technology may not be economically feasible”.

The following plants were tested for their efficacy in removing typical indoor pollutants by these and other studies.

  • Aloe vera was found to be effective in removing benzene and formaldehyde. Aloe is an easy windowsill plant and is also useful for burns. It is a great kitchen plant
  • Spider plant (Chlorophytum comosum) removes benzene, formaldehyde, carbon monoxide, ozone and xylene. This is a plant that is extremely hard to kill. Give it little light and less water and it still survives.
  • Snake plant (Sansevieria trifasciata) Works very well on formaldehyde and ozone. A plant that has been popular for many years as a parlor plant now has some new cultivars. Thrives on low light and neglect.
  • Golden pothos (Scindapsus aures) One of the best for removing formaldehyde and ozone.  Pothos is frequently mistaken for philodendron. Makes a lush vine if kept pinched back.
  • Chrysanthemum (Chrysantheium morifolium) reportedly effective in removing benzene. Again without a very bright cool area it is difficult to grow mums indoors.
  • Dragon plant (Dracaena marginata) is helpful in filtering out xylene, trichloroethylene and formaldehyde. Dracaenas can grow very tall and they lose their bottom leaves as the stalk elongates. A bit of humidity keeps the leaves from browning on the edges.
  • Weeping fig (Ficus benjamina) Good for removing formaldehyde, benzene and trichloroethylene. Ficus tends to drop its leaves without provocation but in the right location is a great plant.
  • English ivy (Hedera helix) English ivy reportedly removes formaldehyde and airborne fecal particles produced by pets. English ivy requires cool conditions to thrive.
  • Corn plant  (Dracaena deremensis ‘Warneckii’) Similar qualities  as Dracaena marginata
  • Chinese evergreen (Aglaonema crispum) Effective in removing formaldehyde, benzene, and carbon monoxide.  Will thrive and bloom with very low light levels.
  • Bamboo palm (Chamaedorea sefritzii) one of the best for filtering benzene and trichloroethylene. Palms are not easy plants to grow indoors unless you have what they like. They need constant moisture and misting.
  • Philodendron (Philodendron oxycardium) removes a number of volatile organic compounds including formaldehyde. An old standby that likes bright light and moderate moisture. Needs pinching for the nicest plant.
  • Peace lily (Spathiphyllum) The best for removing formaldehyde, benzene and trichloroethylene. Also effective with toluene and xylene. Peace lilies thrive and bloom with little care. They need bright light and moderate watering.