Everyone is well aware that plants are our friends. Across the nation and the world, the health-conscious are ingesting ginko biloba to improve memory, St. John's wort to calm the nerves, echinacea to ward off colds and a host of other plant products from mother nature's pharmacopoeia.
But the plants that brighten our interiors can also improve health and allow us to breath easier."If members of your family suffer frequently from sore throats and stuffy noses, they may be reacting to something more serious than allergies or the common cold," according to the Foliage for Clean Air Council of Davidsonville, Md. "Indoor air-contaminants from seemingly benign sources such as gas stoves, furniture, draperies, insulation and carpets can cause a variety of maladies that include respiratory irritation, dizziness, headaches, skin rashes, nausea and vomiting."
Indoor air may be 100 times more polluted than outdoor air, especially in homes and commercial buildings sealed tightly for heating and cooling efficiency.
Manmade products such as paints, insulation, plywood, plastics, carpets, synthetic fabrics and detergents emit up to 300 harmful pollutants, studies have shown.
Standing behind those statements is no less an august organization than the National Aeronautics and Space Administration.
NASA, with assistance from the Associated Landscape Contractors of America, conducted a two-year study directed by Dr. B.C. Wolverton, an environmental engineer from Picayune, Miss. Wolverton has worked as a research scientist for NASA for some 20 years. His study, in the late '80s and early '90s, of the interaction of plants and air found that houseplants, when placed in sealed chambers in the presence of specific chemicals, removed those chemicals from the chambers.
Chemicals used in the NASA tests were trichloroethylene, which is found in printing inks, paints, lacquers, varnishes and adhesives; benzene, a common solvent, which is found in gasoline, inks, oils, paints, plastics and rubber; and formaldehyde, which is found in virtually all indoor environments in grocery bags, waxed papers, paper towels, facial tissues, water repellents, fire retardants, adhesive binders in floor coverings, carpet backings and permanent-press clothing. Formaldehyde also is found in heating and cooking fuels (natural gas and kerosene) and in cigarette smoke.
Based on the NASA study, one plant per 100 square feet of space can help clean indoor air pollutants and help combat "sick building syndrome."
Among those converted to the Wolverton findings is Soo Mullen, plantscape manager for the Plant Gallery in Cincinnati. She and her crew recently installed new air cleaning plants at a local mall. Among the plants she used: large and small schefflera, birds of paradise, crotons, peace lilies, Kimberley queen and Boston ferns, anthurium, Chinese evergreens and kalanchoes. "These plants will clean the air of toxins from new carpets, plastering and painting," she said.
"We did an installation at a factory break room where the employees smoke," she said, adding that the hanging baskets of spider plant both clear the air and boost employee morale.
And, she added, "Plants work as well in homes as they do in offices and commercial buildings."
Wolverton wrote a book called "How to Grow Fresh Air -- 50 Houseplants that Purify Your Home or Office" (1997, Penquin paperback, $15.95) that rates plants' ability to cleanse the air.
In it, he further explains the NASA study, which was conducted to help design a way of cleansing the air in the closed environment of the space station, where astronauts will eventually spend long periods of time.
In the test, plants were both scattered around the sealed test facility and massed in the air purification area. Based on that study, Wolverton was able to identify what pollutants the various plants neutralize and then assign them an efficiency rating from one to 10.