Most plant lovers are keenly aware of the esthetic benefits of plants in indoor spaces from greenhouses and sunrooms to houses and offices, but did you know that some common house plants not only make indoor spaces more attractive, they also help to remove some harmful substances from the air.

In the late 1980s, a study was conducted by NASA and the Associated Landscape Contractors of America (ALCA) to test “Interior Landscape Plants for Indoor Air Pollution Abatement” The initial testing was for the indoor purification of air from the chemicals, Benzene, Trichloroethylene and Formaldehyde.

Formaldehyde is a useful chemical for preserving dead bodies, it is however toxic to live ones. The bad news is that formaldehyde is present in virtually all indoor environments. Some homes have foam insulation containing formaldehyde, and it is commonly used in particle board and pressed-wood. Formaldehyde is also present in many consumer products we bring home including grocery bags and other paper products, and even facial tissue and paper towels, not to mention a host of household cleaning products. Benzene is a commonly used solvent for inks, oils, paint, plastic and rubber and is used in the manufacture of detergents, pharmaceuticals and dyes. Trichloroethylene is a commercial product that has a wide variety of industrial uses. It is used in some printing inks, paints, lacquers, varnishes and adhesives. Seeing the products that contain these toxic chemicals, one could assume that “sick building syndrome” may be more prevalent than most people think.

The NASA/ALCA study concluded that many common houseplants not only make indoor spaces more attractive, they also help to purify the air! 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 are very efficient in processing the gasses necessary for photosynthesis. Because of this, they have greater potential to absorb other gases, including potentially harmful ones.

While they found that some of the plants were better than others for absorbing the heavy pollutants discussed above, all of the plants had properties that were useful in improving overall indoor air quality. They also noted that some plants are better than others in treating certain chemicals. Bamboo palm, Mother-in-law's tongue, Dracaena Warneckei, Peace Lily, Dracaena Marginata, Golden Pathos, and Green Spider Plant worked well for filtering Formaldehyde. English Ivy, Gerbera Daisies, Pot Mums, Peace Lily, Bamboo Palm, and Mother-in-law's Tongue were found to be the best plants for filtering Benzene. The Peace Lily, Gerbera Daisy, and Bamboo Palm were very effective in treating Trichloroethylene.

You will be glad to know that these plants are not only readily available from your local nursery, mail order catalog or website, but they are low light plants that are easily grown and maintained indoors.

1. Philodendron Scandens `Oxycardium', Heartleaf Philodendron
2. Philodendron Domesticum, Elephant Ear Philodendron
3. Dracaena Fragrans `Massangeana', Cornstalk Dracaena
4. Hedera Helix, English Ivy
5. Chlorophytum Comosum, Spider Plant
6. Dracaena Deremensis `Janet Craig', Janet Craig Dracaena
7. Dracaena Deremensis `Warneckii', Warneck Dracaena
8. Ficus Benjamina, Weeping Fig
9. Epipiremnum Aureum, Golden Pothos
10. Spathiphyllum `Mauna Loa', Peace Lily
11. Philodendron Selloum, Selloum Philodendron
12. Aglaonema Modestum, Chinese Evergreen
13. Chamaedorea Sefritzii, Bamboo Or Reed Palm
14. Sansevieria Trifasciata, Snake Plant
15. Dracaena Marginata , Red-Edged Dracaena

As a rule of thumb, allow one houseplant per 100 square feet of living area. The more vigorous the plant, the more air it can filter. As a side benefit, plants, particularly ones with vainy or course leaves, capture dust from the air, and the added humidity from indoor plants causes dust particles to settle. Keep in mind that plants will not do much to alleviate tobacco smoke.

Dr. Christopher J. Kline is a master gardener and writer living in Paradise Valley Arizona. Chris is a member of the Garden Writers Association and a columnist for Garden and Greenhouse Magazine. You can contact him at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it