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Do Houseplants Clean the Air?

"Can plants clean the air?"

Yes. Most plants, including houseplants, will clean the air of harmful toxins and reduce the level of indoor air pollution in your home.

But (there's always a "but" isn't there?) their effectiveness at doing this is often overstated and the environmental conditions in your home will play a significant part in how well they perform.

A number of different plants being grown on a hexagon display wall

Is this the perfect setup for an air purifying powerhouse to create fresh air in your living room, or just a piece of living art?

The Science

Studies and research time and time again will show plants filter indoor pollutants. There is no doubt they have the ability to do this, although the way it's done is not fully understood.

It's clear plants will absorb air into their leaves and while processing it for their own chemical reactions, what comes back out is cleaner air than what went in.

The original research that started this exciting topic was the NASA clean air study in the 1980's. They were trying to find ways to keep the atmosphere inside space stations as clean as possible for astronauts.

The NASA study concluded plants could remove volatile organic compounds (VOC) like formaldehyde and benzene from the air and improve indoor air quality at the same time. Potted plants could help combat sick building syndrome, which can occur within poorly ventilated indoor spaces.

Almost 40 years later, research into the effects plants have on the air around us is still being carried out. For example, a recent study by the University of Birmingham and the Royal Horticultural Society showed that five houseplants in a small office exposed to nitrogen dioxide (NO2) could remove as much as 20 percent from the surrounding air.

However, despite this promising and positive research for any houseplant owner, studies show in real world settings, like those found in our homes, they just can't get the job done.

The reason why it doesn't work

Published scientific research will detail how the researchers have conducted their experiments in their methodology. This means anyone else can repeat the same study and (hopefully) get the same result.

The problem with this is that the method needs to be very precise and controlled so they can be copied, such as putting houseplants in sealed boxes or chambers.

Almost all the research around houseplants and their air cleaning ability has been conducted like this.

Aegagropila linnaei or Marimo in a closed water terrarium

These Moss Balls in a sealed glass jar are effective at cleaning the small space within, but they wouldn't make much impact if the lid was take off.

A sealed box simply does not reflect our home or office environment. We all live and work in spaces that have ventilation of some kind. This means air is being exchanged between the inside and outside constantly.

To keep the air clean inside and reduce VOC levels, houseplants need to remove the pollutions quicker than they can be created. For example, this would mean removing the fumes and emissions from the nearby road or from the occupants already inside the home or office.

In our article asking whether it's safe to have plants in your bedroom, we explained and showed how they only absorb a tiny amount of Oxygen (O2) and Carbon Dioxide (CO2) over an entire night period.

In other words, most plants don't do very much when grown as indoor plants, or rather they do things slowly. Whether growing or filtering the air, they simply aren't as active as many people think.

So they do clean the air, but at a much slower speed than we realistically need for meaningfully improved air quality. The clean air delivery rate that they can achieve is just too low.

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How can I make it work at home?

If you've read the above sections, you will already know one houseplant will barely make a dent in purifying your home. Obviously the more you add, the more that collectively can be done.

But how many plants is enough, you ask? Is it one per square foot or more? Well, the photo below should give you a rough idea.

Many houseplants covering several square feet of space

You'd need this many houseplants per square meter in your home or office space to make meaningful improvements to air quality.

Yes, that many! For some this would be a dream come true. A true jungle of plants. But for most of us, we can't live like this.

It's not all bad news. Houseplants can serve several other functions in homes and offices. From basic decoration pieces to improving humidity levels and reducing dust. Clearly if their air cleaning abilities can be enhanced along the way then even better.

Researches are experimenting with houseplants that have been genetically modified to absorb significantly more pollution from the air. There's evidently an interest and value in getting this to work. Exciting stuff.

What are the best air-purifying plants?

Okay, so we can't meaningfully fix poor air quality issues with houseplants. But some plants do a better job than others and you could be in the camp which takes the view that even a tiny boost is better than nothing.

NASA and Dr Bill Wolverton produced a list of 50 popular houseplants that they proved cleaned the air. This topic and list is really popular so we wrote a more detailed article about it where you can also see all 50 plants.

Grow whatever you like.
You'll get the most from indoor plants if you care for them properly. So keep houseplants that you actually like and will fit into your home.

However, it's now 2022, and indoor gardening is a much bigger hobby than it was 40 years ago. There are hundreds if not thousands of plants now being treated as common houseplants today, that weren't even on NASA and Dr Wolverton's radar.

Yes a Spider Plant, English Ivy or Golden Pothos are all good picks, but almost all plants will have the ability to clean the air. If the research had been carried out today, the "Top 50 Plants" list would look very different and all those websites out there with "best indoor plants" lists wouldn't be dominated by Aloe Vera, Peace Lily, the Snake Plant or Boston Ferns.

Just grow what you like is my advice. Although here are some simple pointers to help when thinking about which are the "best plants" for the job.

  • Bigger is better.
    The bigger the plant, particularly the more surface area of leaves you have, means more respiration. This means higher gaseous exchange and more "filtering".
  • Fast growing plants.
    House plants that are actively growing will be carrying out more Photosynthesis to fuel that growth.
  • The more you have the better.
    One plant is better than none and 100 plants are going to do more collectively than one on it's own (of course, somewhere in-between is perfectly fine too!).
  • Fresh, good, quality soil can help.
    It's thought that the micro organisms living in the soil play a big part in removing the toxins rather than the cells within the plants themselves. Over time the growing medium can break down and reduce the beneficial micro organisms. Repot your plants using good quality compost or potting medium at least every few years.
  • Grow them in optimal conditions.
    Use our care guides to learn how to grow your plants in the best possible way. A well cared for plant will perform better than one struggling in its growing environment. For example, don't put it in a low light spot if it needs bright indirect light.

Let's Sum Up

Yes, indoor plants and indoor gardening are completely worth your time and effort and will provide many positive effects, it's just that very clean indoor air isn't one of them.

The world is changing, becoming more and more fast paced. We need houseplants more than ever, just not as an air filter.

It's too easy to forget about our well being, taking a breath and pausing. Nature and plants can improve your mental health, reduce anxiety, increase productivity, help you recover from stress and promote more calming and peaceful spaces.

Just don't buy houseplants because you need them to clean and filter your air. Open a window, or buy an air purifier instead. (Yes shameless affiliate link, but we've got to keep the lights on in the Ourhouseplants offices somehow!).

The world is changing, becoming more and more fast paced. We need houseplants more than ever... Just not as an air filter.

Plants will filter and scrub the air clean of harmful toxins (the science shows this), but they'll probably be doing it at a much lower level than you might imagine (or hope!).

Several Cereus Jamacaru plants in light grey pots

Not much good as air purifiers, but they will still have other health benefits for you if you invite them into your home.

They'll simply never be able to keep up with the air exchange between the inside and outside of your home. So do houseplants clean the air? Absolutely. Are they better than a mechanical air filter? They're not even in the same league I'm afraid. But they're doing something, and that counts too.



About the Author

Tom Knight

Tom Knight

Over the last 20 years, Tom has successfully owned hundreds of houseplants and is always happy to share knowledge and lend his horticulture skills to those in need. He is the main content writer for the .

Also on Ourhouseplants.com


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