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Interiorscape Forum / Scaper Talk Discussion Forum / General Scaper Talk / Interesting review of plants-as-air-cleaners research
Posted:  26 Feb 2011 20:46  
Check out this article from 2003 from Practical Asthma Review, which provides a good sampling of some of the research reviews that have been done of the Wolverton-type studies that purport to show a significant role for live plants as "air-cleaning machines":

http://www.practicalasthma.net/pages/topics/a ...

It's a lot to digest, I know, so if anyone has questions about the points made in the article, I'd be happy to clarify and/or discuss them here.

Posted:  08 Aug 2011 17:09  
The article states the facts from both sides and does a good job of it.  I don't know if either Bill Wolverton or John Girman are reputable people, I've never delved into either man's background, but if we assume they are, then I think that by losing indoor plants as a means to clean indoor air pollution and improve its quality, then we've lost an important marketing tool.

Since 2003, when the article was published, has any new light been shed on the matter?
Posted:  08 Aug 2011 23:25   Last Edited By: Clem 
There are many current "studies" that aim to support Wolverton's claims, but they are either short on sharing data or the studies have design flaws that render them useless for the purpose of supporting the plants-as-air-cleaners theory.  There have been real-world building studies done that should have given us some good data, but mostly the results of those were mixed at best, contradictory at worst, and therefore inconclusive or useless.

The "Project Carbon" experiments were supposed to determine how good plants are as CO2 sponges (I thought we already knew that plants absorb CO2 to make sugars, but maybe throwing a few thousand more dollars at the question will give some new insights?), but as of today I have not been able to get my hands on the data.  The fact that it's been used as an attention-grabber/headline-machine by the clean air marketing machine to prop up the clean air claims without actually coming forward with the proof may have something to do with that (plus, it was funded by a grant from the National Foliage Foundation, so that also may explain why).

That all begs the question: if the "research" on this topic is so conclusively supportive of the plants-as-air-cleaners mantra, why is it so difficult (or impossible) to obtain (a) the data and its analysis from the studies or (b) peer-reviewed articles about the studies?  Things that make you say, "Hmmmmm....".


P. S.: just because the Practical Asthma review of the research to date as of 2003 is eight years old, it doesn't invalidate the very rigorous analysis of Wolverton's "data" that was described in the article...the math doesn't lie!
Posted:  21 Sep 2011 02:58  
Very interesting article. It certainly appears to be a solid and objective review of the literature and research on this topic. I too would love to see some really definitive and unassailable research demonstrating the beneficial qualities of live plants and clean air because it is a great marketing tool. But absent that information, I am reluctant to make air quality a major selling point to potential clients.

Indeed, I sometimes get client requests for those plants that are best for cleaning the air. These air cleaning plant species lists have appeared in a variety of mass media publications and are largely accepted as fact by the lay public. Consequently, I end up with requests for spider plants and Areca Palms in low light locations. So in some ways, this plants as air cleaners information has become as much a problem as a selling point.

I much prefer to sell plants as environmental enhancements that make interior spaces look more attractive and help people feel better. For most prospective clients that's enough.

~Will Creed
Posted:  21 Sep 2011 15:31  
Will, you are exactly on point...many of the varieties cited in the Wolverton and other studies as the best air-cleaners aren't the best interior plants for our purposes.

More good science needs to be done.  Perhaps the Drexel biowall study will contribute to that.

Posted:  21 Sep 2011 15:48  
I have noticed that many studies, including college professors and foliage research places, use the cheap, flashy plants that are common in grocery stores...crotons, arecas, Dieffenbachia, etc.  Why is that?  Familiarity? Availability?

You are exactly right.  That creates problems for we realists.  I set up my client plant portfolio according to light levels.  I then tell them that I can put any plant anywhere, if they are willing to pay the price to have it replaced regularly.  I tell them that it is my job to give them (paraphrased) the "biggest bang for their buck", and recommend plants that have the greatest longevity for the light levels, but will do what they want.  By phrasing it that way, they are less likely to resent me for not letting them have their junk plants in the dark.

The things we have to do when people get the wrong ideas in their heads!

Posted:  21 Sep 2011 17:35  
One of the biggest problems with this faddist mentality is that people get a wrongheaded understanding of the issue and then run off at the mouth insisting their version of reality is the only truth.  A reasoned, pragmatic study of the issue will eventually produce good data and results for us to consider.

GIGO: garbage in, garbage out.  A study is only as good as its design.  You put in flawed or incomplete data, you get "truth" that is worthless.

Posted:  21 Sep 2011 22:51  
A few months ago I had a lady come into work looking for a Kentia (I think... some sort of palm anyway) because she read on a website (www.ted.com she said... I had no luck confirming her story) that a guy in India (Bombay?) had placed a huge Kentia in the foyer of a building and it completely cleaned the air.  I told her it was probably false, but she wasn't hearing any of that.  She had a younger woman with her, maybe her daughter, and whenever I would explain why it probably wasn't true, her "daughter" would nod her head in agreement behind her back.

She ended up buying one of every plant we had available that was on the NASA clean air list, but this lady was dead set on this being a true story because she read it online.  I should've told her to check out www.theonion.com for all the latest news.
Posted:  22 Sep 2011 00:21  
The Indian story was actually supposedly based on "research" done by an Indian scientist:


There's your "ted" reference.  There is a video on the page if you wish to check it out.  The three plants cited as being able to completely clean all the air in the building are Areca Palm, Sansevieria and Pothos.  Interestingly, this article says the plants should be grown hydroponically, which contradicts the best available current research that says it's the microbes and/or some other component of the growing medium ("soil") that do whatever actual cleaning occurs (a pot of soil with NO plant in it cleans almost half as well as one WITH a plant in it).  So a hydroponic system would, by definition, fail to provide the necessary substrate for the cleaning function.  Go figure...if we could get all the snake oil (snake plant?) salesmen to agree on the method to their madness, we'd at least have a jumping-off point for rational discussion, instead of the current mania (reminiscent of Tulipomania and Orchidmania in Victorian times).

Posted:  22 Sep 2011 22:16  
Clem, all I can say is wow... is there anything you don't know?
Posted:  22 Sep 2011 22:55   Last Edited By: Clem 
I don't know everything, but I can usually find out what I don't know from people I know or resources like books (old-school) and the web.  Anyone can do that if they know how to search efficiently...it's all in your choice of search terms and refining the original search results to get what you want.

Now my secret's out...will you still love me tomorrow?


P. S.: oh, and the other secret?  Logic.  Plain, old-fashioned common sense and logical, critical thinking.  Take the data and make sense of it by making the logical connections between the individual pieces of information to get to the point of revelation.

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