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The Top 10 Plants for Removing Indoor Toxins

A recent NASA study has determined the top 10 plants for reducing indoor air pollution.

By Greg Seaman Posted May 13, 2009

Common indoor plants may provide a valuable weapon in the fight against rising levels of indoor air pollution. NASA scientists are finding them to be surprisingly useful in absorbing potentially harmful gases and cleaning the air inside homes, indoor public spaces and office buildings.

The indoor pollutants that affect health are formaldehyde, Volatile Organic Compounds (benzene and trichloroethylene or TCE), airborne biological pollutants, carbon monoxide and nitrogen oxides, pesticides and disinfectants (phenols), and radon. These pollutants contribute to ’sick building syndrome’, which causes symptoms ranging from allergies, headaches and fatigue through to nervous-system disorders, cancer and death.

Through studies conducted by NASA, scientists have identified 50 houseplants that remove many of the pollutants and gases mentioned above. Dr. B. C. Wolverton rated these plants for removing chemical vapors, ease of growth, resistance to insect problems, and transpiration (the amount of water they expire into the air).

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.

Dr. B.C. Wolverton, researcher and author of “How to Grow Fresh Air — 50 Houseplants that Purify Your Home or Office” (1997, Penguin paperback, $15.95), conducted plant studies for NASA that determined that plants can clean pollutants in homes, offices, factories and retail outlets.

Later, Wolverton expanded the study and assigned plants a rating from one to 10, based on a plant’s ability to remove chemical vapors or indoor air toxins, ease of growth and maintenance, resistance to insect infestation and the rate at which water evaporates from the leaves.

Dr. B.C.Wolverton’s book, “How to Grow Fresh Air”, is available in book stores, directly from Penguin books, New York (1-800-526-0275) or online at websites such as www.amazon.com and www.bn.com.

The source report is no longer available on NASA’s website (this is a link to where it was linked from – search for “foliage”). All of the information regarding the study can be found within Dr Wolverton’s book.

More information on Wolverton’s research can also be found here: http://en.wikipedia.org/wiki/List_of_air-filtering_plants

Also, here is a good TED talk on the subject.

Top ten plants for removing formaldehyde, benzene, and carbon monoxide from the air:

1. Areca Palm (Chrysalidocarpus lutescens)

Also called the “Butterfly Palm”. An upright houseplant that is somewhat vase shaped. Specimen plants can reach 10 to 12 foot in height. Prefers a humid area to avoid tip damage. Requires pruning. When selecting an Areca palm look for plants with larger caliber trunks at the base of the plant. Plants that have pencil thin stems tend to topple over and are quite difficult to maintain.

2. Lady Palm (Rhapis excelsa)

Also called the “Lady Palm”, this durable palm species adapts well to most interiors. The Rhapis are some of the easiest palms to grow, but each species has its own particular environment and culture requirements. The “Lady Palm” grows slowly, but can grow to more than 14′ in height with broad clumps often having a diameter as wide as their height.

3. Bamboo palm (Chamaedorea seifrizii)

Also called the “reed palm”, this palm prefers bright indirect light. New plants will lose of some interior foliage as they acclimate to indoor settings. This plant likes to stay uniformly moist, but does not like to be over-watered or to sit in standing water. Indoor palms may attract spider mites which can be controlled by spraying with a soapy solution.

4. Rubber Plant (Ficus robusta)

Grows very well indoors, preferring semi-sun lighting. Avoid direct sunlight, especially in summer. Young plants may need to be supported by a stake. The Ficus grows to 8’ with a spread of 5’. Wear gloves when pruning, as the milky sap may irritate the skin. Water thoroughly when in active growth, then allow the soil to become fairly dry before watering again. In winter keep slightly moist.

5. Dracaena “Janet Craig” (Dracaena deremensis)

The Dracaena grows to 10’ with a spread of 3’. Easy to grow, these plants do best in bright indirect sunlight coming from the east/west. They can adapt to lower light levels if the watering is reduced. Keep the soil evenly moist and mist frequently with warm water. Remove any dead leaves. Leaf tips will go brown if the plant is under watered but this browning may be trimmed.

6. Philodendron (Philodendron sp.)

One of the most durable of all house plants. Philodendrons prefer medium intensity light but will tolerate low light. Direct sun will burn the leaves and stunt plant growth. This plant is available in climbing and non-climbing varieties. When grown indoors, they need to be misted regularly and the leaves kept free of dust. Soil should be evenly moist, but allowed to dry between watering.

7. Dwarf Date Palm (Phoenix roebelenii)

A hardy, drought-tolerant and long-lived plant, the Dwarf Date Palm needs a bright spot which is free of drafts. It grows slowly, reaching heights of 8-10’. The Dwarf Date Palm should not be placed near children’s play areas because it has sharp needle-like spines arranged near the base of the leaf stem. These can easily penetrate skin and even protective clothing.

8. Ficus Alii (Ficus macleilandii “Alii”)

The Ficus Alii grows easily indoors, and resists insects. It prefers a humid environment and low to medium light when grown indoors. The Ficus Aliii should not be placed near heating or air conditioning vents, or near drafts because this could cause leaf loss. Soil should be kept moist but allowed to dry between watering.

9. Boston Fern (Nephrolepis exaltata “Bostoniensis”)

The Boston fern grows to 4’ in height with a spread up to 5’. It has feathery ferns which are best displayed as a hanging plant. It prefers bright indirect sunlight. Keep the soil barely moist and mist frequently with warm water. This plant is prone to spider mites and whitefly which can be controlled using a soapy water spray. Inspect new plants for bugs before bringing them home.

10. Peace Lily (Spathiphyllum “Mauna Loa”)

The Peace Lily is a compact plant which grows to a height of 3’ with a 2’ spread. This hardy plant tolerates neglect. It prefers indirect sunlight and high humidity, but needs to be placed out of drafts. For best results, the Peace Lily should be thoroughly watered, then allowed to go moderately dry between waterings. The leaves should be misted frequently with warm water.

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Posted in Healthy Home Tags Air Quality, Plants, toxins

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Comments

Posted by Aran Seaman

Oct 5, 2009 5:49 pm

Thanks Justin,

We just updated the article to clarify this: NASA does not have the report on their website, but the source information can be found in Dr. B.C.Wolverton’s book, “How to Grow Fresh Air”, available in book stores, directly from Penguin books, New York (1-800-526-0275) or online at websites such as <a href=”http://www.amazon.com” target=”_blank”>www.amazon.com and <a href=”http://www.bn.com.” target=”_blank”>www.bn.com.

Posted by Guest

Oct 25, 2009 6:01 pm

Which of these are dangerous for animals? We have two cats and I'd rather not introduce any plants that will make them sick if they nibble on them.

Posted by Greg Seaman

Oct 26, 2009 1:51 am

The following three plants from the above list should be avoided if there are cats in the home:
Rubber Plant (Ficus robusta), Dracaena “Janet Craig”, Philodendron.

Posted by Guest

Oct 26, 2009 1:57 am

Thank you!

Posted by Eartheasy Blog » Formaldehyde link to leukemia confirmed: how to limit exposure in the home

Dec 1, 2009 12:19 pm

[...] as effective filters for formaldehyde, benzene and carbon monoxide from indoor air. See the list of houseplants identified by NASA researchers as useful in absorbing potentially harmful gases in indoor [...]

Posted by MMiley

Feb 13, 2010 8:42 pm

Very interesting and helpful post! And a reminder that plants are an important part of nature's design to renew our environment. You may also want to point our that the plants on this list are low-maintenance and easy to grow.

Posted by Cheryl

Feb 14, 2010 5:46 am

I've known for yearsd about the Peace Lily and it works beautifully. We had a new kitchen put in and all of the particle board is filled with Formaldehyde which made my mother's very sensitive eyes burn constantly. We placed two or three Peace Lilies in the kitchen area and after as little as a week the effects were noticeable. I always get them if I lay new carpet as well. I had no idea about the other plants. Fabulous article! Our cats have never tried to chew on them either. I don't have the NASA link but is this scientific link enough for you Colin? http://sciencelinks.jp/j-east/article/200415/0000...

Posted by sarah

Feb 14, 2010 2:17 am

the only problem is that it takes a couple of days for a plant to purify the air in a room, but only a few seconds to ruin it all when you open the window

Posted by Aran Seaman

Feb 15, 2010 2:11 am

The NASA study is not available online, but all of the information can be found in Dr. B.C.Wolverton’s book, “How to Grow Fresh Air”.

Posted by Aran Seaman

Feb 15, 2010 2:30 am

Just for reference (there are some critics out there saying this is an "advertorial", because it's not linked to the study)

The study and reports were published on NASA's website, but the links no longer work. You can see where they were linked from on this page: http://www.ssc.nasa.gov/environmental/docforms/wa... (search for "foliage" to find the reports).

All of the information regarding this study can be found in Dr BC Wolverton's book, which you can purchase here if you like: http://www.amazon.com/How-Grow-Fresh-Air-Plants/d...

Posted by Aran Seaman

Feb 18, 2010 4:15 pm

Here is a good TED talk on the subject as well: http://www.ted.com/index.php/talks/kamal_meattle_...

Posted by Greg Seaman

Feb 18, 2010 5:27 pm

The air inside the home is more toxic than outdoors. When you open the window you are helping clean you indoor air. "Ventilate" is one of the prescriptions for improving indoor air quality.

Posted by Tim

Feb 18, 2010 6:21 pm

How many plants to put in a room seems to be a problem for me. Given the volume of air in a room, how many plants does it take to neutralize that volume? Also I realize it depends on the building materials in a room, for instance, a FEMA trailer would need to be all plants, while a stone house may need few?

Posted by Greg Seaman

Feb 18, 2010 6:30 pm

Plants should be considered only a part of the regimen for ensuring healthy air inside the home. Ventilation and source identification are the prime treatments. Ventilation is obvious – exchange your indoor air with fresh air. Source identification can be more difficult – e.g. mold buildup in the laundry room can be a cause that can be alleviated by cleaning the mold and better venting.
Too many plants can also be a problem in itself by raising humidity levels to a degree that encourages mold.

Posted by Guest

Feb 19, 2010 6:40 pm

Hey! on a vaguely related note: I know fungi aren't plants, technically, and these won't clean indoor air pollution, but interestingly enough the oyster mushroom when cultivated on top of a crude oil spill will absorb the oil just like it would absorb other organic matter and break down the oil into harmless compost. It's an effective way to clean up a spill and the mushrooms are even safe to eat afterward.

http://www.uas.coop/node/1011

Posted by kfinity

Feb 20, 2010 10:27 am

Pretty sure it is available online. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa….

Posted by M Wilson

Feb 20, 2010 10:52 am

How much air does a small plant actually process? I would like to see the numbers of how long it would take for an average size house plant to process the amount of air in a single human breath.

Posted by Val

Feb 20, 2010 8:01 pm

Dr. Wolverton also wrote a more academic work on plant water purification that laid out the principles of what is today known as Living Machine water recovery systems. http://www.ssc.nasa.gov/environmental/docforms/water_research/water_research.html

Posted by John

Feb 22, 2010 5:12 pm

Good post….we can't survive without clean air….

Posted by Houston Apts

Feb 24, 2010 1:40 pm

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Posted by Rob

Feb 24, 2010 6:22 pm

I have often hear that the air inside our homes are more polluted than the air outside. I even know someone who is extremely allergic to formaldehyde that after several attempts to decrease the amount of it in is home had to actually sell the house and moved further south in an old farm house. This is a excellent post glad I found you on Stumble Upon

Posted by hopelikeit

Feb 27, 2010 3:08 am

in the 70's and 80's it was the trend to have lots of house plants…along with the jute hangers you could knot up in a flash. I don't know when plants went out of "style" but recently i've started to buy house plants again. It's comforting to take care of them….although not too sure they are thriving.

Posted by Lisa

Mar 2, 2010 6:21 pm

Wonderful article. I have A LOT of plants that I usually keep outside during the warmer months and bring them in during the winter. One of my dogs loves to feel like she is in the "jungle" among all the plants.

Posted by GGilette

Mar 2, 2010 6:30 pm

Very good article! Indoor plants are also good for people living in apartments in cities because they remind them of the beauty and importance of protecting the natural environment.