Friday, January 14, 2011

Spider plants

A spider plant inhabits a corner of my home office, in fact I can't remember a time when I didn't have a spider plant somewhere in my home. I poached this particular plant from an off-shoot of a friend's plant and it now has an off-shoot of its own. Based on my reading about spider plants, I think I'll pot up the new off-shoot and create another plant.

Spider plants, or Chlorophytum comosum, originally came from South Africa to become a very common house plant. Their tolerance to some neglect makes spider plants a great plant for busy folks. I don't know what spider plants look like in the wild, but mine is the typical domestic variety with long, spikey green leaves with a white stripe up the middle. I've also seen spider plants with solid green leaves. It isn't my prettiest plant - the tips of the leaves tend to go brown (I hear regular fertilizing can help prevent this) - but what the spider plant does for my indoor air keeps me growing them.

Nicely insulated houses, like mine, can have significantly more polluted air than the outside. In the winter, when windows and doors are kept closed, these air pollutants can build up. Fortunately, cleaning up indoor air has been extensively studied by NASA because an extended space mission can't possibly bring enough air for the whole trip – so the air needs to be cleaned and re-used (the same hold true for water in space).

In a house or office building the most common pollutants include carbon monoxide, formaldehyde and benzene – each comes with its own negative effects. Plants provide an easy, low energy way to remove air pollutants. Since this is not a new idea, a technical term exists – phytoremediation, which is defined as the use of plants to remove environmental pollutants or render them harmless. The most effective plants for dealing with air pollution include: philodendrons, golden pothos, spider plants and chinese evergreens. My spider plant can effectively remove lots of carbon monoxide. Some say a spider plant removes about 560 micrograms per hour of formaldehyde (ref). They go on to say that a spider plant can remove all the formaldehyde in a room in under 4 hours, but, it didn't provide any back up data so I'm suspicious.

More than just the plant does this good work, microbes found in the soil also aid in removing pollutants. To create an optimized plant filter combine the plant and its associated soil microbes with activated carbon* - a combination that is already available commercially.

There is another side though – some argue that plants as air filterers are not that effective in real world rooms (as opposed to controlled conditions in a lab). Plants also increase humidity in a room, which can lead to mold issues if you aren't diligent. I tend to have lots of plants – I enjoy seeing them and believe they improve air quality, although perhaps not as much as some say they do. I think a reasonable additional step is to also avoid adding chemicals to your indoor environment (like cleaning chemicals or particle board furniture) and to air out rooms whenever the weather permits.

*As a tangent – what is activated carbon? It's a small carbon chunk with an extremely rough and porous surface. This creates a huge surface area for the size of the chunk, according to wikipedia: just one gram of activated carbon has a surface area in excess of 500 square meters. This huge surface area is available to bind to pollutants (and other stuff).

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