The use of plants to purify indoor air is attracting increasing interest from the general public. The purifying properties of plants have indeed been demonstrated in laboratories. However, in real-life situations, plants do not have any significant effect on indoor pollution. For allergy sufferers, they even constitute a danger to the environment.
The notion of a depolluting plant was introduced by NASA in the 1980s. Dr. Wolverton was conducting research on air purification in space shuttles. In 2010, thanks to the Phytair programme, the Observatoire de la Qualité de l'Air Indoor has deepened our knowledge of the ability of plants to purify the air.
Indeed : agglomerated wood furniture, paints, glues, varnishes, solvents, deodorisers, coatings, detergents and carpets present in our homes emit toxic volatile organic compounds (VOCs). These chemical compounds damage the lungs. and can cause various headaches.
Three houseplants, which are very popular with the general public, were exposed to highly concentrated pollutants: Devil's Ivy, the Spider Plant and the Dragon Tree. Under controlled laboratory conditions, they capture between 30% and 90% of the pollutants present in the air. They are effective on carbon monoxide (CO), formaldehyde, ammonia, toluene, xylene, trichloroethylene and benzene. Some of these pollutants are present in cigarette smoke and in household products (insecticides).
There is also a wide variety of plants considered as depolluting plants :
With their roots and leaves composed of living micro-organisms, these plants convert pollutants into organic products in order to feed themselves.
The last phase of the Phytair programme took place under real exhibition conditions. It did not demonstrate the effectiveness of depolluting plants on indoor air quality. With a realistic number of plants in a room, air purification is in fact almost nil. For Joëlle Colosio, head of the air quality evaluation service at Ademe, the awarding of an "air purification capacity" label to a plant therefore appears "largely premature".
Plants can have undesirable effects, especially on people with allergies. Some plants spread allergenic pollen. Others have allergenic sap. Above all, the soil in the pots is rich in moulds, including the spores are allergenic. Finally, houseplant care products can themselves pollute the air.