I don't know if it's improving the best of one's plant's effect, rather more if it works or doesn't, or maybe which plants are best at doing this. I've heard Spiders (Chlorophyutum), Pothos & Sansevierias (of which I grow many).

I've read NASA's done work in this area, have you read any of their materials?

Yes. That's most of what I was referring to when I said that the studies seemed solid, and that the people who did them chose to try plants including pothos and spider plants based partly on their abuse-resistance.

They didn't do anything special to grow the proper soil microbes. Here's a typical quote: "All plants tested were obtained from nurseries in our local area. They were kept in their original pots and potting soil, just as they were received from the nursery ... ."
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930073077_1993073077.pdf

It seems obvious to me that the populations of soil microbes won't be the same in a pot of peat-mud and rotting roots as in a pot of gritty mix and optimally-repotted healthy roots, just because the same species of plant is growing in each. But as far as I've seen, NASA has had nothing to say about it.

I think you might be overthinking this. Frankly, I'd go w/ the plants mentioned, already known to excel at cleaning the air.

Then I'd be watching what kinds of products are entering the home.

New furnishings are well known to off gas chemicals like formaldehyde (sp?).

Also bizarre things folks think nothing of using which are chemically pretty significant, things like Glade-Plugins which get plugged into outlets, G_d knows what chemicals come off there. Even air fresheners the ones that don't plug in, just a myriad of chemicals to inhale. (Personally, this has always made me wonder if there's some connection to Autism.)

Folks seems to miss the fact that since these chemicals are in the air & inhaled, we really should consider them as drugs & regulate their manufacture to control such exposures (especially to pregnant women, young kids & the elderly).

Yes, Karen is right on!

Then many of us have the choice anything but natural natural products that work just as good if not better than the ones sold in the chemical isle at the stores, including , bleach, detergeants and the such.

I use a Melliluca products and I can bet you my air quality in my home is much better than a room full of plants.
Have you ever stood in the isle at the grocery store where all the household cleaning products are stored for more than ten minutes? Many people actually store the same chemicals throughout their whole house, especially in the cubbards. I feel bad for the poor children exposed to all those, including myself in my kid days.

Mike

Don't know what Melliluca products are, but I will say, I sometimes put out a saucer of baking soda just to absorb any odd, stray odors or just freshen things up.

As an ex-smoker who smoked for 42 yrs., I can tell you btwn the plants & the baking soda, my home didn't smell much of tobacco, kind of astonishing really (tho' I did keep all my windows open an inch or 2, even in the dead of winter).

Overthinking stuff is what I do for fun.

I use unscented cleaning products, as much as possible. I find those "air freshener" perfume dispensers kind of nasty.

Melaleuca is the genus name for tea tree. It's also the name of a company that sells various wellness products.

Quote;
Posted by dsws; "It seems obvious to me that the populations of soil microbes won't be the same in a pot of peat-mud and rotting roots as in a pot of gritty mix and optimally-repotted healthy roots, just because the same species of plant is growing in each. "
*************
Soil microbes are going to need soil to grow a large population. The less organics you have in your mix, you will likely limit or change the varieties of microbe species you have in the pots, meaning, for example, a species that consumes benzene that requires a certain organic substrate may not be present at all in a gritty mix or in hydro-culture. Plus the higher use of nutrients might be damaging to the microbes with either method. With less organic materials in your gritty mix or hydro-culture you would probably build a microbe population (as long as it never dried out) closer to an aquarium filter then a typical house plant pot with an average soil mix.

It may not be the way favored in this crowd but folks have kept healthy potted plants in peat based mixes for hundreds of years. All you have to do is go to an old conservatory to see these older plants kept this way.

Thanks. Some stuff there I hadn't found.

If the chemicals are consumed by soil bacteria, why do the plants need to be photosynthesizing faster than they do in typical interior lighting? The first source I'm looking at mentions 1150 lux, which is about what Wikipedia describes as tv-studio lighting, or twice what it describes as typical office lighting. That's not extreme.

I don't put much stock in the person who couldn't find anything about removal of xylene and toluene. Lots of the sources mention them, including some cited by Wikipedia, as well as WP itself of course. Wikipedia isn't a source itself, but it's by far the world's easiest place to find cited sources. If someone didn't bother to look at most of the sources cited by WP, I have to wonder where they did look.

Thanks Nancy, that was a lot of good info. I knew about the NASA Wolverton studies in the 80's, the interior foliage industry expected them to spark a plant renaissance. Didn't quite happen. I've read some of the links in your post already, don't have time right now to check out the others, do you know if any of them, or any other studies, spcifically focus on the types of soil microbes or actual plant processes that produce the "cleaning" effects?

Some time ago, (and I'm too lazy to look it up again, so I'm winging it from memory), I did up a three point bulletin about what you'd need to know about how to use plants to produce the best results as re: using plants to clean air.

1. pot size matters. Specifically, diameter, or rather, exposed surface area.

2. the number of plants recommended is far more than most people will ever put in a room. for a fifteen by fifteen room, you'd be looking at approx. ten plants in 8-10" pots.

3. use a variety of plants. Not all plants draw the same materials, or at the same rates. you'd have to research each and every plant and each and every chemical, and that research just isn't going to happen. so a few things are known, but many aren't. and that just isn't going to change, so use as great a variety as you can grow effectively.

dsws... when i said that most indoor light is inadequate, i meant that indoor light falls off dramatically as compared to the light available outdoors. this is why everyone's photos are blurry when shot inside. our eyes have 'software' that automatically adjust for the lower levels, so it doesn't *seem* so dark. also, people then make things worse and put their plants off in dark corners.

i'm not saying that decent indoor light near a window is inadequate, especially for the lower light plants - pothos, aglaonemas, sans, parlour palms, etc. if the plant is healthy and growing, i'm assuming that's good enough.

in dark northern winters, plants are barely doing anything, even if they are right up near windows. this is why many voices on this forum will suggest being more careful of watering and fertilizing during this time. plants are transpiring very little water when it's dark.

also, i'd say that more than half (maybe 75%) of the "what's wrong with my plant?" threads on this and other house plant forums are caused by inadequate light. overly moist potting soils are not nearly as problematic when plants are grown outdoors in better light. the plants transpire the excess water away. and, the plants are better able to defend themselves from bugs because they are making more chemical defenses and can out grow a problem.

so, i don't think that you need special high intensity lighting, especially if you choose plants with lower light needs, but you may need some sort of supplemental lighting (fluorescents?) at least for the dark seasons.

theficuswrangler... i haven't seen much info on the 'bugs.' i ran across what i'd describe as a 'comment' - ie this wasn't a scientific study being written up - that you really do need the plant. i'm surprised in a way, because you'd think that once some dirt built up in the filter bed, some bacteria would take hold and grow. this is what happens in aquariums that have under-gravel filters. you can even buy bottles of 'bugs' at fish stores to help get your culture started faster.

anyway, the only other info on the bacteria i've found says that different plants support different bacteria types. also, the bacteria will evolve or gain new member types based on the types of food (dust and chemicals) they are exposed to. in other words, a fan assisted planter in a smoking lounge will get better with time in breaking down cigarette smoke chemicals.

strobiculate... yes, plant number and surface area is the reason that folks are using fans. when you add a fan to a filter bed that contains hydroponic ceramic balls (LECA) combined with some activated charcoal, you can effectively multiply the plant numbers. so, on most of these planters, they'll say things like "this one has the cleaning capacity of 100 plants, or 200 plants, or whatever." this to me seems very doable. in this case (a fan assisted planter), a typical 2,200 square foot house might only need 2 or 3 planters - depending on size - to take care of the house.

i've been sorta tempted to buy one of the fan assisted planters to see if i notice any difference in my household air. i'm not really concerned that it's 'toxic' because my house is a hundred years old and leaks like a sieve. but my air 'stinks'. for lack of a better description, i call it "old house smell" or "attic smell".

the other reason to do it is simply that i'm interested in this sort of thing. i mean, why have normal hobbies like normal people :-)

cheers,

nancy

ps if i don't buy one, i'm tempted to try to make one myself. i already grow most of my plants in Hydroton media, so the only change would be to add some activated charcoal (from a pet store). the main problem i haven't figured out is how you keep the fan from drying out the media too much.

you'd think that once some dirt built up in the filter bed, some bacteria would take hold and grow. this is what happens in aquariums that have under-gravel filters

I think it would -- if the contaminants were present at high enough concentrations to serve as a major food source for the bacteria. But we're talking about residual solvent evaporating from glue months or years after it's apparently dry. The plants provide the main food source, and the pollution is just a little extra bonus (from the bugs' point of view).

Well, it's all very interesting, and I think we can all agree there's opportunity for tons of research. Anyone know any kids open to inspiration?

Nancy, I would like to address your comment that 75% of problems people are having are due to inadequate light. It may seem like 'six of one half dozen of the other', but to me it looks like the problem is incorrectly dealing with soil moisture. The reason is this: water is the variable over which people have the most control. Often, for whatever reason,the folks who are looking for help can't really do much about the light, but what they CAN do is adjust the water they give their plants so that the plants, while not attaining the levels of vigor found under adequate light, can still look lovely and bring much enjoyment to their people.

dsws...

"The plants provide the main food source, and the pollution is just a little extra bonus (from the bugs' point of view)."

Exactly!

theficuswrangler...

in your screen name, you list yourself as zone 9/10. this is a whole different ballgame than large areas of the US. first off, you're going to get more hours of winter light, and depending on where you live, you're likely to get more sunshine/clear skies.

i live in portland OR and it is so dark in the winters that we have a houseplant book written for our area called "Green plants for gray days." it can be summarized as "pretty much you can only grow spaths, sans, aglaonema and pothos unless you supplement your winter lighting." that is only a very slight exaggeration. no amount of cutting down the watering to adjust for plants that need higher light levels will keep them happy in the winter. the exception might be some of the succulents that can effectively go dormant for the winter. a sun room will make a huge difference because even a dark, overcast sky is still pretty "bright" compared to the light that comes in through a window.

Good point Nancy. I should have said that people can adjust the amount of water they give their plants, and they can also make sure the plants they have are suited to the light they can provide. So while I still think that overwatering is the major cause of houseplant death, trying to have plants that are unsuited to the available light is a big one also.

With supplemental lighting, as I understand it, the biggest thing is to put the light really close to the plant. Otherwise, most of the light is going to waste providing illumination for the rest of the room. And there's no way you're going to illuminate a whole room at levels high enough to make an appreciable difference.

Of course, there's a whole 'nother forum for lighting.

dsws... i've never done much supplemental lighting, but you're correct that the light needs to be close to the plant (as long as it's not an incandescent light that can burn the foliage). there are a lot of very good threads here on gardenweb and out on the web that can help you with this if you want to try it.

every year of living in the "land of the dark" puts me closer to trying it. maybe i should just give up and move to a sunnier climate :-)

nancy_pnwzone8(OR zone 8)

ps here are some links if you're interested.

Wolverton Environmental Services

http://www.wolvertonenvironmental.com/

Plant Air Purifier

http://www.plantairpurifier.com/

Andrea

http://www.andreaair.com/

Inside Urban Green - What did Bill Really Say?

http://www.insideurbangreen.org/2009/11/my-entry-1.html

Phytophilter Technologies

http://www.phytofilter.com/

Plants are the Strangest People - Indoor Plants as Air Purifiers

http://plantsarethestrangestpeople.blogspot.com/2008/04/indoor-plants-as-air-purifiers.html

Kamal Meattle: How to grow fresh air

http://www.youtube.com/watch?v=gmn7tjSNyAA
(i would be remiss for posting this link without providing more info. in
this TED talk, it sounds like they just added some plants to a big
office building, like you would see in a typical cubicle farm, and -
shebang - the air was cleaned. what he doesn't show is that they have a
full on indoor grow op with high intensity lighting and full hydroponic
plumbing. the grow rooms are tied into the building's HVAC. there was
another video that showed the set up but i can't find it now.)

I would add these links:

1. Wikipedia

Houseplants together with the medium in which they are grown can reduce components of indoor air pollution, particularly volatile organic compounds (VOC) such as benzene, toluene, and xylene. Plants remove CO2
and release oxygen and water, although the quantitative impact for
house plants is small. Most of the effect is attributed to the growing
medium alone, but even this effect has finite limits associated with the
type and quantity of medium and the flow of air through the medium.[25]
The effect of house plants on VOC concentrations was investigated in
one study, done in a static chamber, by NASA for possible use in space
colonies.[26]
The results showed that the removal of the challenge chemicals was
roughly equivalent to that provided by the ventilation that occurred in a
very energy efficient dwelling with a very low ventilation rate, an air
exchange rate of about 1/10 per hour. Therefore, air leakage in most
homes, and in non-residential buildings too, will generally remove the
chemicals faster than the researchers reported for the plants tested by
NASA. The most effective household plants reportedly included aloe vera, English ivy, and Boston fern for removing chemicals and biological compounds.

Plants also appear to reduce airborne microbes, molds, and increase humidity.[27] However, the increased humidity can itself lead to increased levels of mold and even VOCs.[28]

When CO2 concentrations are elevated indoors relative to outdoor
concentrations, it is only an indicator that ventilation is inadequate
to remove metabolic products associated with human occupancy. Plants
require CO2 to grow and release oxygen when they consume CO2. A study
published in the journal Environmental Science & Technology considered uptake rates of ketones and aldehydes by the peace lily (Spathiphyllum clevelandii) and golden pothos
(Epipremnum aureum.) Akira Tani and C. Nicholas Hewitt found
"Longer-term fumigation results revealed that the total uptake amounts
were 30−100 times as much as the amounts dissolved in the leaf,
suggesting that volatile organic carbons are metabolized in the leaf
and/or translocated through the petiole."[29]
It is worth noting the researchers sealed the plants in Teflon bags.
"No VOC loss was detected from the bag when the plants were absent.
However, when the plants were in the bag, the levels of aldehydes and
ketones both decreased slowly but continuously, indicating removal by
the plants".[30]
Studies done in sealed bags do not faithfully reproduce the conditions
in the indoor environments of interest. Dynamic conditions with outdoor
air ventilation and the processes related to the surfaces of the
building itself and its contents as well as the occupants need to be
studied.

While results do indicate house plants may be effective at removing
some VOCs from air supplies, a review of studies between 1989 and 2006
on the performance of houseplants as air cleaners, presented at the
Healthy Buildings 2009 conference in Syracuse, NY, concluded "...indoor
plants have little, if any, benefit for removing indoor air of VOC in
residential and commercial buildings."[31]

Since high humidity is associated with increased mold growth,
allergic responses, and respiratory responses, the presence of
additional moisture from houseplants may not be desirable in all indoor
settings.[32]

sourse: https://en.wikipedia.org/wiki/Indoor_air_quality#Effect_of_indoor_plants

2.Critical Review: How Well Do House Plants Perform as Indoor Air Cleaners?

Dingle et al. (2000) reported on a field study of three portable
office buildings in Perth, Australia to test removal of formaldehyde by
plants. Five plants (five species) were added to each room every two
days to a maximum of 20 plants (at 2.44 plants per m2) after nine days.
Two adjacent portable office buildings were used as controls with no
plants. The mean formaldehyde concentrations were about 850 ppb, except
with 20 plants. The authors state that the results show “no change in
formaldehyde concentrations with the addition of 5 or 10 plants in the
rooms and only an 11% reduction in formaldehyde concentrations with 20
plants in the room.” They did not indicate that this reduction was
statistically significant....

With this caveat firmly in mind, it is hardly surprising that the HBI
study failed to find any effect on pollutant removal by plants, despite a
reasonably strong study design in terms of using controls. The study
by Dingle et al. found only an 11% reduction in formaldehyde with the
highest loading of plants (20 plants in a room or a loading of 2.44
plants per m2), which is not feasible in the real world and is probably
not statistically significant.

...

Sourse: http://www.buildingecology.com/articles/critical-review-how-well-do-house-plants-perform-as-indoor-air-cleaners/

I think people overestimate the ability of plants to clean the air. That's why EPA don't write about plants as cleaner at all:

Epa wrote about Mechanical air filters, Electronic air cleaners, Gas-phase air filters, UVGI cleaners , PCO cleaners, Ozone generators , Portable air cleaners but EPA don't write about plants as cleaner at all.Sourse: http://www.epa.gov/iedweb00/pubs/residair.html

If you use plants as cleaner You need to test air inside your house or flats. You need to use complex devices to test air otherwise you may find that you don't have any benefit from plants at all. And this is only placebo. You can spend your time for nothing.

Only complex devices to test air inside your houses or flats can help you. Please don't trust so much NASA or Wolverton. Be critical. To read Critical Reviews too. Сheck the air in your homes with complex devices.

And this is very interestint too:

"I have been buying my houseplants directly from growers in Florida. It
has recently come to pass that I have accumulated a chemical toxicity in
my bloodstream due the the chemicals that these tropical plant growers
are using on their plants!! I never even considered this in my plan for
this business!! Here I am trying to educate people on the benefits of
living plants in their homes and I am selling them plants full of
insecticides and fungicides and what have you! Since my store is small
and is filled to the brim with these plants - all of a sudden I started
having symptoms associated with chemical "overload" in my system from
touching and pruning and breathing around these plants!!"

Sourse: http://forums2.gardenweb.com/discussions/1470201/how-to-purge-out-the-chemicals-in-my-houseplants

Thank you Sans2014 (Fred), for this link.

You need also test your bloodstream. You can have a more bad things than good things from plants. It is necessary to test this with the scientific instruments.