House Plants Can Improve Indoor Air Quality – Fact or Fiction?

The harmful effects of outdoor air pollution have received much media coverage over the last few decades, but in recent years there have also been several studies into the impact of poor indoor air quality on our health.

It seems incredible to believe, but in actual fact the air that we’re breathing in inside our homes and workplaces can be up to 5 times as polluted as the air outdoors.

With estimates that many of us now spend approximately 80% of our time indoors each day it’s a bit of a sobering thought as to what we may be inhaling into our lungs quite unwittingly.

One suggestion that’s been garnering interest is the use of indoor plants as a means to mitigate against poor indoor air quality.

Sounds like a simple solution.  But does it actually work?

In this article we’re going to consider this proposition in more detail.

If you’re short on time you can jump straight to the section you’re most interested in by clicking the link in the table below, or read on for the full article.

Why Should We Be Concerned About Poor Indoor Air Quality?

To understand the interest in using plants as a means of improving air quality, it might be useful firstly to have a quick look at why poor indoor air quality is such a bad thing. 

According to the World Health Organisation, an estimated 3.8 million premature deaths each year from non-communicable diseases (including stroke, ischaemic heart disease and lung cancer) are attributed to exposure to household air pollution.

This problem is more acute in developing countries where there is still a large reliance on solid fuels as a means of heating the home and cooking.

But even in developed nations poor indoor air can be responsible for a number of serious medical conditions including respiratory disease and cancer.

And it can be the most seemingly innocent of things we all have around our homes which can clog up our air with nasty toxins.

For example, synthetically-fragranced products such as candles, air fresheners, cleaning products and personal care items contain a mixture of chemicals which may emit potentially harmful volatile organic compounds (VOCs) into the air.

Finding solutions which can help improve our indoor air is therefore more crucial than ever.

Where Did The Idea Of Using Plants First Come From?

The idea that plants may be able to help improve indoor air quality began to receive attention following an initial research study by NASA scientists in 1989.

They were looking at ways to improve the air quality in space stations – obviously opening a window to let in some fresh air a few hundred miles above the Earth is not a viable option!

Experiments were conducted in sealed chambers designed to simulate space station conditions, looking specifically at the presence (and removal) of 3 particular organic chemicals – benzene, formaldehyde and trichloroethylene.

The data obtained led scientists to believe that plants may be able to absorb some gases present in the air (including VOCs), in turn making the air indoors cleaner and safer to breathe.

Further research by one of the lead scientists on the original study followed in 1996, where it was proposed that plant-filtered rooms contain 50-60% less airborne microbes, such as bacteria and mold spores.

In addition, there have been subsequent studies in the intervening years on the effects of plants on indoor air quality by institutions such as Penn State University and the University of Georgia.

How Do Plants Clean Indoor Air?

Most of us will have learned about basic photosynthesis in our high school biology class.

Essentially it’s the process by which plants convert light and carbon dioxide into chemical energy to fuel their growth, and return oxygen to the air.

But some scientists now believe that plants can also remove other gases in addition to carbon dioxide, absorbing them through pores on the surface of their leaves and through their roots.

The plants will then either metabolize the pollutants themselves or incorporate them into the plant tissue.  Or the pollutants may instead be neutralized by micro-organisms living in the soil of the plants.

What Are The Best House Plants For Cleaning Indoor Air?

The best indoor plants for air pollution removal according to the NASA report and some other scientific studies since include:

  • Aglaonema
  • Aloe Vera 
  • Areca Palm
  • Boston Fern
  • Devil’s Ivy (also known as Golden Pothos)
  • English Ivy
  • Japanese Royal Fern
  • Mother-in-Law’s Tongue
  • Peace Lily
  • Philodendron
  • Purple Waffle Plant
  • Snake Plant
  • Spider Plant

How Many Plants Do You Need To Clean The Air In A Room?

In terms of the number of plants needed to clean the air inside a room, the NASA research suggests that you need at least 1 plant per 100 square feet of home or office space.  Ideally each potted plant should be approximately 10-12 inches in size.

It’s also recommended to dust the leaves of each plant with a damp cloth at regular intervals to help ensure the proper absorption of air particles and toxins.

Conflicting Views

The title of this article posed the question as to whether it’s fact or fiction that plants really can improve the quality of the air indoors.

In spite of the original NASA study, and the further research subsequently carried out by one of its main authors, some experts remain unconvinced.

There is a feeling in some quarters that while the NASA study may have produced positive results these relate only to small-scale, limited environments and don’t translate equally to real-life situations.

For example, a memo published in 1992 by the US Environmental Protection Agency asserted that ‘to achieve the same pollutant removal rate reached in the NASA chamber study would require 680 plants in a typical house”.

It’s also been suggested that some plants themselves may emit VOCs, in addition to the plastic pots in which they’re grown, some micro-organisms living in the plant soil, and the pesticides used to treat them.

And it’s been argued that there are actually a number of different factors which determine just how well a plant can remove toxins from the air such as the plant species, the type of soil in which it’s planted, lighting conditions and indoor temperature.

So it appears that for the moment opinion is somewhat split, and that it’s perhaps not yet possible to give a definitive answer one way or another to this question.

However, given the increasing problem of premature deaths caused by toxic indoor air it’s an area likely to be high on the agenda of public health bodies and scientific organisations in their search for a solution to this issue.

3 Other Steps We Can Take To Improve The Air We Breathe

While science continues to examine the connection between plants and air pollution, there are a number of steps we can each take in the meantime to try and improve the air we breathe in on a daily basis.

The first is to try and minimise the use of things which can cause our indoor air to become polluted with VOCs, such as air fresheners and household cleaning products.

Switching to natural, chemical-free options can also save us money, in addition to being better for our health and the environment.

Secondly, we should aim to ensure there’s adequate ventilation in our homes and offices and allow a good supply of fresh air to circulate round on a regular basis.

In a drive to become more energy-efficient we have a tendency nowadays to seal up our living and working spaces as tightly as possible with enhanced insulation.

But in order to avoid a toxic build-up we do need to let air in, so throw open your windows for a while each day if you possibly can.

Lastly, you may want to consider investing in an air purifier, particularly if you or someone you live with suffers from allergies, asthma or underlying medical conditions and is more vulnerable to pollutants in the air.

These are electrical devices which trap contaminated airborne particles inside a filter, and there’s a large choice available on the market to suit all budgets and specific needs.


Personally, I’m going to continue to display potted plants all round my home.

They’re relatively inexpensive to buy, attractive to look at, and in my opinion help to create a calming, relaxing environment. 

I may not know for sure yet whether they’re truly making my air significantly healthier to breathe, but I figure on the balance of evidence so far it’s got to be worth a shot.

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