The Simple Science

For half a century, scientists have been carrying out experiments to show the world that plants are good for our health and happiness. That's a lot of experiments.

We worked with scientists at RMIT University and the University of Melbourne to take this world of research and make it easy to understand. They analysed scientific articles and research studies and boiled the story down to two big benefits.

Two big benefits

Removing air-borne toxins created by paints, furniture finishes and air pollution.

Just one or two plants starts to increase air quality significantly in a space.

Creating feelings of relaxation, inspiration and positivity.

The first few plants give a limited benefit, but once you start to create a look, wellbeing increases quickly. Variety of sizes and species is key.

Just one plant can improve your air 25%

And a few more can do a whole lot more. Plants absorb airbone pollutants, including:

In an average 4x5m space:

What are vocs

Organic chemicals are widely used in household products, including paints, furniture finishes and many cleaning products. Being volatile means they can easily become vapours or gasses, which contaminate our air. Concentrations of many VOCs are up to 10 times higher indoors than they are outdoors. And yes, they can be bad for your health.

Particulate matter, like ash and dust

Inorganic compounds, such as carbon monoxide

Volatile organic compounds: VOCs

A few plants can make you feel more relaxed, inspired and positive

RMIT also investigated direct mental health benefits of plant, such as improved mood and concentration, and indirect benefits, such as productivity and positive social behaviour, that indoor plants might have caused.

They found that there is very little wellbeing benefit in just one plant, but once you start to create a "look" in your space, wellbeing begins to increase significantly.

What's more, complexity matters. The greater the mix of sizes and varietals, the greater the benefits.

In outdoor spaces such as yards and courtyards, plants have limited ability to improve air quality. However, a good array of plants will still improve wellbeing significantly.

In an average 4x5m space:

The rating system

The rating system makes it easy to understand the health and wellbeing benefits at a glance for different sized rooms. These are all based on medium sized plants (around 30cm tall).

Small Room (3m x 3m)

Medium Sized Room (4m x 5m)

Large Sized Room (8m x 8m)

Size Matters

Size of a plant is important in its ability to improve your space. When it comes to air quality, total leaf are and total size of the rootball are important (so go for bigger leaves and bigger pots).

As a rule of thumb, when considering the rating system above, discount smaller plants to be worth 1/3 of a medium plant. While large plants are worth 1.5 times a medium plant.

Small
Medium
Large

Species matters

The science above all works on an averaging method. It's designed to be simple, to give you well estimated rules of thumb for improving your health and wellbeing.

When it gets to the details, some plants are better at improving air quality than others. For that sort  of level of information, ask the experts at your local nursery.

NASA's Clean Air Study also has good information.


Learn more

The method

RMIT studied 101 articles and research reports and crunched them into one easy-to-understand index.

The studies looked at a plant's ability to absorb airborne pollutants, such as particulate matter, inorganic compounds such as carbon monoxide, and volatile organic compounds (VOCs).

RMIT also investigated direct mental health benefits of plant, such as improved mood and concentration, and indirect benefits, such as productivity and positive social behaviour, that indoor plants might have caused.

All outcomes were taken through a peer-reviewed expert panel to ensure validity of the findings.

Note: benefits from plants are inherently variable and depend on a number of factors, not all of which have been studied to date.

BASEline approach

As much as possible we used Best Available Scientific Evidence "BASEline" to determine the relationships between plants and health and wellbeing. Where our information was not adequate to contribute to the index, our expert panel estimated the most likely cause and effect relationships.

Want to know more?

Get the full science report here:

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