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Air Purifying Plants – Do They Work?

It’s that time of year again, winter is coming. We close the windows and doors of our home to keep out out the cold, and in the process we lock in all kinds of chemical pollutants. Never fear, a few air purifying plants will help with that problem. This must work since all kinds of home magazines, newspapers and web sites tell you it works. Headlines like “the 10 best plants for removing pollutants in your home” appear daily this time of year. How well do plants work at cleaning the air in our home?

Air Purifying Plants

Air Purifying Plants – Do They Work?

Air Purifying Plants Do Remove Some Pollutants

There is no doubt that plants do absorb chemicals and particulate matter from the air. Our outdoor environment is improved by the presence of plants.

It only makes sense that having plants indoors would have the same effect and in fact this is quite true. House plants do remove chemicals from the air in our home. They do remove CO2 and they remove some other pollutants. The real question that needs to be asked is the following:

Do house plants reduce the amount of pollutants in the air inside the home?

These might seem like the same statements but they are not. Plants can and do remove pollutants, but do they remove enough of them to make a difference to the amount of pollutants in  our air? If you had two identical homes and one had a few plants growing and the other did not, would you see a difference in the air quality? That is the important question.

Air Pollutants in the Home

So what is the big deal? What kind of air pollutants do we have in our home? Why is it suddenly a problem?

Years ago homes in developed countries were quite drafty. Clean air from outside was constantly being blown through our homes, exchanging polluted air with fresh air. Things were good, except that heating bills were very high. Along came the better sealed homes–remember the R-2000 homes? Homes being built today are so much more air tight that they prevent fresh air from coming in.

At the same time, more and more products in the home are man-made and many of these products give off a constant low level of polluting chemicals. The plastic carpet, the fabric on the chairs, and all of our electronics are polluting our air. You might remember formaldehyde insulation? And those air fresheners, scented products and spray cans are some of the worst polluters.

So while our homes have become more air tight, the stuff in our homes are producing more pollutants than ever before. The result is a poor quality of air in our homes, especially in winter.

NASA Tests Plants

In order to better understand this issue, we need to go back in time and see where the scientific evidence started. Some early studies showed that plants absorb VOCs (volatile organic carbons), such as benzene, toluene, octane, and trichloroethylene . This lead NASA to do some research on air purifying plants, which they reported in 1989.  The results showed that in a lab situation, plants did in fact absorb VOCs from the air.

That started an avalanche of recommendations in the popular press. “House plants purify the air in the home”.  People started recommending “the best air purifying plants” for the job. What a relief–buy a few house plants and we are all saved from air pollution.

By now I am sure you have guessed that this is all a myth.

The Birth of a Myth

Before looking at the reality of the situation it is educational to understand how it all went wrong. This myth was born, like many others, as a result of two main mistakes.

  1. Results obtained in a controlled lab situation were extrapolated to a field environment–our homes.
  2. Actual data was exaggerated and misinterpreted by the media.


Both of these mistakes happen all the time with almost all topics, and they happen a lot with gardening advice.

The early testing done on plants used small lab chambers, that were highly controlled, and which were crammed full of plants. They did not simulate the situation in our homes and the researchers doing the work never claimed their work showed house plants would reduce pollution in our homes.

The media took the results, selected the numbers they liked best, jumped to unfounded conclusions and announced “air purifying plants work to clean our air”.

To have a closer look at the details of these mistakes have a look at A Myth is Born – Plants Don’t Purify Air.

Plants Don’t Improve Our Indoor Air

More recently a few researchers have studied the effect of plants in real world situations. These studies were done in offices, but this is fairly similar to our homes.

These studies show that the level of pollutants do NOT go down over time.

Why is there such a difference in the studies? The main reason for the difference was that the initial lab work was done with a lot of plants in a small space. To establish this in our homes we would have to have a 100 house plants in every room. That’s not practical–it would be great to have all these plants–but not practical. Having a plant or two for each room in your home will just not make much of a difference.

The second reason for the difference is that in our homes the material in them is constantly giving off pollutants. These are produced faster than plants can remove them. In the lab test chambers, the pollutants were injected once and then the air was monitored to see a reduction in pollutants. These are two very different situations.

Here is what the EPA has to say on their FAQ page (ref #2): “The only available study of the use of plants to control indoor air pollutants in an actual building could not determine any benefit from the use of plants“.

Best Plants for Reducing Pollutants

You will find lots of lists recommending the best plants for removing home pollutants. I am not sure where this information comes from. Most of the studies show that there is little difference between one plant and another. The size of plant and the number of plants is more important than the variety.

Plants vs Microbes

If plants removed pollutants from the air, then more leaves should remove more pollutants. In one study NASA measured the ability of certain plants to remove pollutants–this gave them a base line value. They then removed some leaves. It seems pretty obvious that if you remove leaves, the plant will remove less pollutants–right? Wrong. What they found was that removing leaves improved the plants ability to remove pollutants.

Long story short, and after many more tests, they were able to show that it was the microbes in the soil that were removing most of the pollutants. The microbes were much more efficient at removing pollutants than the plants–surprise!

It seems quite obvious to me that if we went back to dirt floors we would solve our home pollution problem, but the popular press has not picked up on this idea!

Air Purifying Plants Will NOT Clean Your Air

House plants are a great addition to your home, but they have no real effect on the quality of your air, unless you have hundreds of them. The microbes in the soil are more valuable than the plants as far as cleaning air goes, but even they have little effect on the quality of your air.

The best thing you can do is to allow fresh air into your home, and reduce the number of cleaners, and perfumed products you use. Fewer renovations, and fewer electronic devices will also help. Stop using products sold in spray cans.

Kamal Meattle – Plants and Air Purification

Kamal Meattle presented a very convincing TED Talk video on line promoting the idea that plants purify air. You can see the video and read the full story at, Kamal Meattle – Plants and Air Purification.

New Study on Office Buildings

Added October 2016.

A new field study has been brought to my attention and is reviewed here. The study is called The Potted-plant Microcosm Substantially Reduces Indoor Air VOC pollution: I. Office Field Study by Ronald A. Wood et al.

This study was done using three buildings at the University of Technology, Sydney, Australia. Zero, 3 or 6 plants were put into various small offices and total VOCs were monitored over time. There was no reduction of VOCs in any of the buildings as a whole. Building 1 was an administrative office building and there was no reduction of VOCs in the offices with plants. Building 2 and 3 were mixed use offices containing both offices and laboratories. Some reduction of VOCs occurred inside the offices with plants but not in the building at large. There was no difference between using 3 or 6 plants and the reduction was only seen when the offices had high levels (>100 ppb) of VOCs present. These high levels are above that found in a normal home.

In conclusion, the study indicates that adding such plants would have a limited effect, if any, in a home with average VOC levels.

A more detailed analysis can be found in the discussion section of A Garden Myth is Born – Plants Don’t Purify Air.

Do Houseplants Increase Oxygen Levels in the Home?

Several people commented on my posts that houseplants were still valuable in the home because they increase oxygen levels and that makes us feel better.

I have now looked into this claim in Do Houseplants Increase Oxygen Levels?


1) How Well do Air Plants Perform as Indoor Air Cleaners?:

2) Indoor Air Pollution:

3) Photo Source: Spaceo


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Robert Pavlis
Editor of
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

7 Responses to 'Air Purifying Plants – Do They Work?'

  1. Larry Iles says:

    Thanks for the good read and being a voice of reason.

    I don’t think most people understand that the microbes living on and around the roots are a major part of the bioconversion of micronutrients into useful plant food, and most of those micronutrients would be toxic wastes to you and I.

    It is that series of symbiotic relationships that process soil nutrients (human toxins) into complimentary growth for each successive microbe and eventually the plant itself. Nearly all of those toxins are either broken down into less toxic forms to be consumed by another, used for energy and growth for each one in their own time.

    Trace amounts of some toxins will be absorbed into the plants virtually unchanged, but locked safely away by the plant itself within its cell walls… Until the leaves eventually drop off and begin to decay. Once that happens, the toxins that remain will be released back into the atmosphere from whence they came and the cycle begins again.

  2. Tar says:

    Love this article! A lot less bullshit than what I’d expect from an average blog post.

    Curious to what your actual solution would be?

    As for myself:

    Some of these air purifiers, they are rather expensive and I will not write the brand here seemingly do the trick of actually removing VOCs. What is your verdict on them?

    • This is not your average blog 🙂

      I have not looked into air cleaners, but there is no reason that they would not work to some extent – the question is do they remove VOC’s faster than they are produced?

  3. Sean says:

    Since you at least read the research papers on VOC removal (which is actually remediation), you made the correct statement by saying that it is the microbes that do this. The original data wasn’t exaggerated, it was just performed in optimal conditions for a very short period of time. Chemical remediation happens in all areas of the plant (for which there are specific names for each area), but the root zone is where the majority of where it happens. But you you forgot to mention that these microbes can’t survive without the plants…

    All plants have relationships with microbes that make local nutrients available to the plants in exchange for food (sugars) from the plant.

    While the media may be portraying this information in a different way, they’re not completely wrong. Air purifying plants WILL clean your air, because they create the microbial communities to do so. Do you expect the media to tell people “use dirt to clean your air” ?

    I have personally performed these tests in isolated chambers with formaldehyde, benzene, and xylene. I have seen the chemical levels diminish, and the plant survive. You haven’t debunked anything, you have just provided the correct context for what’s actually going on.

    • It is true that without the plants you would probably not have as many microbes in the soil. But there are two main points to my argument that plants do not purify the air. One was that it was the plants. The second point, which is the main one, is that the amount of plants needed to have any impact on a room is far more than what anyone would use.

      The media and all those thousands of click bait sites claim plants clean the air in your hone. They don’t. The air remains the same with or without a few plants.

      In order for anyone to make that statement they would need to show this in a study. The study would analyze VOC levels in a typical room, not in a chamber. There have only been a couple such studies and they do not show a reduction of VOC in the rooms. Since you seem to be involved in this kind of research, let me know if you find such studies.

      The original data was exaggerated, not by the scientist, but by the media. They selected the single highest value in the study and used that for reporting the effectiveness of plants. The media also reached conclusions that the original NASA study never reached – another form of exaggeration.

  4. Our living/plant room might say a different story 🙂 – just a joke.
    True that one has to have lots of plants in a room for a real effect, but can you please, place this myth on top of the ‘good’ ones for all the other benefits the house plants bring?

    • Robert Pavlis says:

      Absolutely–there are many benefits to having plants in the home. I’d love to have a 100 in each room.