Having recently moved to a very high-traffic area, we became interested in augmenting the quality of our indoor air through the use of plants. Presented here are our motivation and the preliminary results of our search.

To start, we found that:

• It isn’t uncommon for indoor air to be many times more polluted than outdoor air (up to 70 times!);
• Traffic isn’t the problem: most of this indoor pollution is due to chemicals we use within home and office and to out-gassing;
• Much of it is carcinogenic and causes short term discomfort and disease. Indoor air pollution is considered the main culprit for a 60% increase in asthma over the last decade.

We can reduce the toxic baddies by making informed choices when purchasing, thanks to helpful sites such as Environmental Health Association of Nova Scotia’s Guide to Less Toxic Products.

Out-gassing, on the other hand, is more problematic. There are tons of materials in use that release toxic gas for months or years after fabrication. These include carpeting, polish, glues, vinyl and all sorts of plastics… basically anything that gives off something resembling "new car smell". These gasses contain things like:

• Formaldehyde
  Found in plywood, grocery bags, waxed paper, fire retardants, etc.
• Benzene
  Found in inks, oils, plastics, paints, detergents, synthetic fibers, etc.
• Trichloroethylene
  Found in inks, varnishes, adhesives

These and other chemicals commonly released into indoor air can cause joint pain, depression, headaches, chest pains, asthma, ear infections, chronic fatigue, dizziness, recurrent sinus infections, mood swings, loss of sleep, cancer and other goodies.

The chemicals may also act as "sensitizers", causing people to begin reacting to exposures to other substances that had never been bothersome before (for instance perfumes, paint, felt tip marking pens, cigarette smoke, etc.). This chemical sensitivity is caused by an inability to metabolize or detoxify the extra burden of chemicals.

Making informed choices will help reduce the sources of out-gassing in your environment (for instance, you can replace vinyl or PVC blinds with bamboo or curtains) but getting rid of all toxic sources is next to impossible. One easy and potentially enjoyable way of removing these substances from the air is the house plant.

A NASA study, aiming to find plants for air purification on a future off-world base, identified a number of plants that are quite efficient in removing formaldehyde, benzene and other nasties. Another NASA study (1989) showed that houseplants were able to remove up to 87 percent of toxic indoor air within one day and later work showed that one spider plant could detoxify a 100 cubic foot room polluted with formaldehyde, within six hours.

To be truly effective, you need numerous plants: a potted plant per 100 square feet is recommended (though some sources suggest more than seven per room!). You also need a complete ecosystem… It was found that the plants don’t perform the detoxification work wholly on their own: the combination of soil, plant and helpful bacteria was much more effective at removing toxins than an isolated plant (for instance, in a hydroponic system). The plant must therefore be potted, ideally in a way that maximizes the plant root-soil area’s exposure to air.

The following is a list of plants that are known to function as efficient air detoxifiers (as well as producing yummy oxygen, of course). There are other house plants that have similar impact on air quality. We chose these because of their high efficiency and low maintenance, although points were also awarded to plants with low light requirements or were esthetically pleasing.

Name – Sci.	Lighting requirements	Notes	Look & Feel
Chinese Evergreen – Aglaonema sp.	Tolerate full shade.	Removes Formaldehyde. Large leaves, happy in the shade. Avoid cold water when watering.
English Ivy – Hedera helix	Partial Shade	Removes Benzene. Enjoys indirect sunlight but will be happy in lower lighting conditions. Non-variegated varieties tolerate more shade. Has a lower temperature range than most (down to 7 degrees C, doesn’t enjoy temps greater than 18C), avoid placing near heat source. Water moderately and regularly.
Golden Pothos, Devil’s Ivy – Epipremnum aureum	Partial Shade	Removes formaldehyde (one of the top three removers). Water regularly. Leaf drop == over watering.
Sansevieria / Snake plant / Mother-in-law’s tongue – Sansevieria trifasciata	Wide range, full sun to partial shade.	Removes formaldehyde. Tough plant, handles extremes. Growth will slow but is ok in partial shade. Comfortable at room temp (18-21C) but can deal with 12-30C. Prefers a dry spell to being overly watered: water sparingly.
Spider Plants – Chlorophytum comosum	Partial shade, bright but indirect.	Removes formaldehyde (in the top three plants for this purpose).
Schefflera / Australian umbrella tree – Schefflera actinophylla	Bright, indirect light.	Grows quickly in light. Ok with slightly lower temperatures (though never below 13C).
Dracaena – Dracaena deremensis	Bright, indirect light.	Removes Benzene and Trichloroethylene. Keep between 18 - 24 degrees C. Well-drained soil, let dry between wartering.
Ficus – Ficus sp.	Full sun	Removes formaldehyde. Tough plant but doesn’t like change – select a location and avoid moving. Likes well-drained soil, water moderately. Avoid cold drafts.
Aloe Vera – Aloe barbadensis	Full sun	Very efficient formaldehyde absorber at lower concentrations. Well-drained soil, let dry between watering.

Happy breathing to you all.

Copyright © 2005 P. Deegan, All Rights Reserved.