(The Best Years in Life) People have long known about the
psychological benefits of brightening their homes and offices with decorative
houseplants. What many may be overlooking are the physical health benefits of
having plenty of these plants to remove harmful pollutants from the air and
replace them with fresh oxygen.
Not long ago, indoor air pollution was not considered a health threat; most
homes and public buildings leaked so much that air often was replaced every
couple of hours. After energy shortages occurred in the 1970s, more and more
people began to insulate their houses and office buildings to conserve energy
and lower heating and cooling costs. As a result, indoor air might linger for
five hours or more allowing pollutants to accumulate. Moreover, synthetic
building materials used in modern construction have been found to produce
potential pollutants that remain trapped in unventilated buildings. These
trapped pollutants can result in what is often called the Sick Building
In the late 1980s, a study by NASA and the Associated Landscape Contractors of
America (ALCA) resulted in excellent news for homeowners and office workers
everywhere. The study concluded that common decorative houseplants such as
bamboo palms and spider plants not only make indoor spaces more attractive, they
also help to purify the air. While it`s a well known fact that plants convert
carbon dioxide into oxygen through photosynthesis, the NASA/ALCA study showed
that many houseplants also remove harmful elements such as trichloroethylene,
benzene, and formaldehyde from the air. With our ultra modern homes and offices
that are virtually sealed off from the outside environment, this study is just
as important now as when it was first published.
The NASA study, Foliage Plants for Removing Indoor Air Pollutants from Energy
Efficient Homes, was conducted by Dr. B.C. Wolverton, Anne Johnson, and Keith
Bounds in 1989. While it was originally intended to find ways to purify the air
for extended stays in orbiting space stations, the study proved to have
implications on Earth as well.
Under controlled conditions, NASA and ALCA spent two years testing 19 different
common house plants for their ability to remove these common pollutants from the
air. Of the 19 plants they studied, 17 are considered true houseplants, and two,
Gerbera Daisies and Chrysanthemums, are more commonly used indoors as seasonal
The advantage that houseplants have over other plants is that they are adapted
to tropical areas where they grow beneath dense tropical canopies and must
survive in areas of low light. These plants are thus ultra-efficient at
capturing light, which also means that they must be very efficient in processing
the gasses necessary for photosynthesis. Because of this fact, they have greater
potential to absorb other gases, including potentially harmful ones.
NASA found that some of the plants were better than others for absorbing
pollutants, with certain houseplants found to remove as much as 87 percent of
indoor air pollutants within 24 hours. However, all of the plants had properties
that were useful in improving overall indoor air quality. NASA also noted that
some plants are better than others in treating certain chemicals. For example,
English Ivy worked better than some other plants for treating air contaminated
with Benzene. The Peace Lily was very effective in treating Trichloroethylene
and the Bamboo Palm worked well for filtering Formaldehyde.
After conducting the study, NASA and ALCA came up with the following list of
plants most recommended for treating air pollution. Note that all the plants in
the list are easily available from your local nursery.
Heartleaf Philodendron - Philodendron scandens `oxycardium`
Elephant Ear Philodendron - Philodendron domesticum
Cornstalk Dracaena - Dracaena fragrans `Massangeana`
English Ivy - Hedera helix,
Spider Plant - Chlorophytum comosum
Janet Craig Dracaena - Dracaena deremensis `Janet Craig`
Warneck Dracaena - Dracaena deremensis `Warneckii`
Weeping Fig - Ficus Benjamina
Golden Pothos - Epipiremnum aureum
Peace Lily - Spathiphyllum `Mauna Loa`
Selloum Philodendron - Philodendron selloum
Chinese Evergreen - Aglaonema modestum
Bamboo or Reed Palm - Chamaedorea sefritzii
Snake Plant - Sansevieria trifasciata
Red-edged Dracaena - Dracaena marginata
Here is a list of the pollutants NASA tested for and the plants they found that
worked the best for each one:
Trichloroethylene is primarily used in the metal degreasing and dry cleaning
industries; also in printing inks, paints, lacquers, varnishes, adhesives. In
1975 the National Cancer Institute reported that an unusually high incidence of
hepatocellular carcinomas was observed in mice given TCE by gastric intubation
and now considers this chemical a potent liver carcinogen.
The NASA study found that the best plants for removing trichloroethylene are the
Gerbera Daisy, Chrysanthemum, Peace lily, Warneckei, Dracaena marginata
Benzene is a very commonly used solvent and is also present in many common items
including inks, oils, paints, dyes, plastics, rubber, dyes, detergents,
gasoline, pharmaceutical, tobacco smoke, synthetic fibers. In addition it is
used in the manufacture of explosives.
Benzene has long been known to irritate the skin and eyes. In addition, it has
been shown to be mutagenic to bacterial cell culture and has shown embryotoxic
activity and carcinogenicity in some tests. Evidence also exists that benzene
may be a contributing factor in chromosomal aberrations and leukemia in humans.
Repeated skin contact with benzene will cause drying, inflammation, blistering
Acute inhalation of high levels of benzene has been reported to cause dizziness,
weakness, euphoria, headache, nausea, blurred vision, respiratory diseases,
tremors, irregular heartbeat, liver and kidney damage, paralysis and
unconsciousness. In animal tests inhalation of benzene led to cataract formation
and diseases of the blood and lymphatic systems. Chronic exposure to even
relatively low levels causes headaches, loss of appetite, drowsiness,
nervousness, psychological disturbances and diseases of the blood system,
including anemia and bone marrow diseases.
The best plants for removing benzene were determined to be English Ivy, Dracaena
marginata, Janet Craig, Warneckei, Chrysanthemum, Gerbera Daisy, Peace lily
Formaldehyde is a ubiquitous chemical found in virtually all indoor
environments. The major sources which have been reported and publicized include
urea-formaldehyde foam insulation (UFFI) and particle board or pressed wood
products used in manufacturing of the office furniture bought today. It is used
in consumer paper products which have been treated with UF resins, including
grocery bags, waxed papers, facial tissues and paper towels. Many common
household cleaning agents contain formaldehyde. UF resins are used as
stiffeners, wrinkle resisters, water repellents, fire retardants and adhesive
binders in floor coverings, carpet backings and permanent-press clothes. Other
sources of formaldehyde include heating and cooking fuels like natural gas,
kerosene, and cigarette smoke.
Formaldehyde irritates the mucous membranes of the eyes, nose and throat. It is
also a highly reactive chemical which combines with protein and can cause
allergic contact dermatitis. The most widely reported symptoms from exposure to
high levels of this chemical include irritation of the eyes and headaches. Until
recently, the most serious of the diseases attributed to formaldehyde exposure
was asthma. However, the Environmental Protection Agency (EPA) has recently
conducted research which has caused formaldehyde to be strongly suspected of
causing a rare type of throat cancer in long-term occupants of mobile homes,
where particle board and other sources of formaldehyde are used extensively.
When it comes to removing formaldehyde, the best plant choices are Azalea,
Philodendron, Spider plant, Golden Pothos, Bamboo palm, Corn plant,
Chrysanthemum, Mother-in-law`s tongue.
Many people feel that the use of houseplants is not needed if they are using an
air purifier. However, research has shown that even if you use a HEPA air filter
or an ionic air purifier, there is a lot of difference that can still be made by
many common house plants, which act as a living air purifier. With the exception
of an activated carbon filter, common indoor air filters, such as HEPA or
ionizers, will totally miss the toxic household gases, such as carbon monoxide,
formaldehyde, and volatile organic gases (VOG).
According to NASA, one plant should be used for every 100 to 120 square feet of
office or living space and the plants should be in at least six inch containers
with nothing covering the potting soil. In addition to removing pollutants in
your home or office, plants also make for a more pleasant place to live and work
- where people feel better, perform better, and enjoy life more. Here are some
of the other benefits from having indoor plants:
Plants are a Source of Oxygen - Plants take in carbon dioxide and produce oxygen
through the process known as photosynthesis. The more plants you have, the more
oxygen you will receive.
Plants Make You Happy - House plants make people feel calmer and more
optimistic, says Bruno Cortis, M.D., a Chicago cardiologist. Interestingly, he
says that studies have shown that hospital patients who face a window with a
garden view recovered more quickly than those who had to look at a wall.
Plants Fight Fatigue and Colds - According to a University of Agriculture in
Norway study, indoor plants can reduce fatigue, coughs, sore throats and other
cold-related illnesses by more than 30 percent, partially by increasing humidity
levels and decreasing dust.
Plants at the Office - Major corporations and work environments are beginning to
catch on that adding plants indoors does wonders for employee health and morale.
According to one study published in Rehabilitation Literature, a manufacturing
company integrated plants into its office so that no employee would be more than
45 feet from greenery. The result? Company administrators said they noticed
enhanced creativity and increased productivity in employees. One popular plant
to use in offices is the Dragon Tree plant. Besides being one of the most
effective in removing harmful impurities from the air, it`s exotic looks adds
character to any room.
It is important to note though that not all plants are good as indoor air
cleaners and that some plants are poisonous and should be handled with care, or
not at all if you have small children. Some examples of toxic plants include:
Nightshade, Creeping Charlie, Foxglove, Oleander, Sago Plant, Privet,
Rhododendron, Umbrella Plant, Ivy, Ripple ivy, Sweet Pea, Vinca, Spider Mum, and
Poinsettia. Consumers looking for houseplants that purify air should probably
steer away from the above named plants if they have young children and indoor
pets, as these plants can sometimes be fatal if consumed.