by Tami Port MS

Created on: June 04, 2009   Last Updated: August 25, 2009

Houseplants are often used decoratively to bring little bit of nature's beauty indoors. But these green accents do much more than just sit pretty; plants are natural air filters that can significantly improve interior air quality, particularly during the months of inclement weather when houses are shut up tight. Who says so? NASA.

* NASA Houseplant Study *

About 20 years ago, NASA, together with the Associated Landscape Contractors of America (ALCA), conducted a study designed to find ways to purify the air in space stations, but like many of NASA's scientific findings, their results also provided information useful to the average earth-dweller.

All plants take in carbon dioxide and produce oxygen during photosynthesis (turning sunlight energy into plant food), but the NASA/ALCA study revealed that many houseplants also remove harmful elemental pollutants from the air. And these natural air filters run on sunshine; no electricity required! What could be greener than that?

The researchers tested the air scrubbing abilities of 17 common houseplant varieties, focusing primarily on three harmful chemicals: benzene, formaldehyde, and trichloroethylene. Formaldehyde is found in many building materials and some cleaning products. Benzene is a commonly used in oil and paint formulations, and trichloroethylene in adhesives, inks, paints and varnishes. Therefore, all three tested pollutants are likely to be found in the average home.

* Type, Size and Number of Houseplants for Best Air Quality *

The top ten recommended plants are listed below. All are commonly available from most local nurseries and are shade-tolerant species; meaning that you don't need to have a sunny location in order to grow them. Most will do well in moderate and even low light environments. How many plants do you need to improve the air quality of your home? Any plant will help, but for optimal air quality, the NASA study recommended using at least fifteen plants each in 6" or larger containers.

Top 10 Houseplants (based on being easy to grow and ability to clean air):

1. Reed palm (Chamaedorea sefritzii)
2. Spider plant (Chlorophytum comosum)
3. Janet Craig dracaena (Dracaena deremensis `Janet Craig')
4. Weeping fig (Ficus benjamina)
5. Peace lily (Spathiphyllum `Mauna Loa')
6. English ivy (Hedera helix)
7. Heartleaf philodendron (Philodendron scandens `oxycardium')
8. Elephant ear philodendron (Philodendron domesticum)
9. Golden pothos (Epipiremnum aureum)
10. Selloum philodendron (Philodendron selloum)

All houseplants listed above have some level of toxicity if certain parts of the plant are ingested. See the websites of the New York Botanical Garden or Denver Plants for more information on potentially poisonous houseplants.

* Sources *

Wolverton, B. C. et al (1989). "NASA report Interior Landscape Plants for Indoor Air Pollution Abatement."

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