Do houseplants actually improve air quality?
With more and more of us working from home, are there any benefits in bringing the outdoors, in?
Most of us have been spending a lot more time at home these past couple of years, prompting us to ask questions about the quality of the indoor air we breathe. Pre-COVID reports show that we Brits spend more than 90 per cent of our time indoors, where levels of some toxins can be up to five times greater than they are outdoors.
The internet is full of claims that houseplants can help, with just about every wellbeing site boasting its own top-10 rundown of the most powerful air-purifying plants. But is there any truth to the claims?
Unfortunately, not much. Most of the articles, if they cite any evidence, point to a NASA study from 1989. Back then, scientists were investigating plants’ ability to remove harmful chemicals called volatile organic compounds (VOCs) from the air of sealed environments such as space stations. In our homes and offices, sources of VOCs include paints, varnishes, furniture, carpets and printers. The study found that over a 24-hour period, several species of plants could indeed remove up to 70 per cent of one, or more, of the three VOCs tested.
But the results don’t translate well to the typical home or office, according to a 2019 review that revisited the NASA data, along with 11 other studies from the decades since. For starters, the experiments typically used fans to waft the VOCs over the plants, and carbon filters to collect them – setups that most of us don’t have in our homes.
More importantly, the plants were placed in small, sealed chambers. But the buildings we live and work in are surprisingly leaky. In fact, the researchers estimate that you’d need to squeeze between 10 and 1,000 plants into each square metre of your home to approach the rates of VOC removal already happening through passive indoor-outdoor air exchange.
Research shows that houseplants do have a range of other benefits, however. They help regulate humidity. They can improve mood and boost productivity. And they look good, to boot. But if you want to freshen up the air in your home, your best bet is to buy an air purifier with a high-quality filter or – depending on where you live – to open a window.
- How many plants would I need in an airtight room to be able to breathe?
- Is it true that you shouldn’t keep plants in the bedroom?
- Can any plants live without sunlight?
- Are some plants better than others at sucking up carbon dioxide?
Asked by: Sam Nicholls, via email
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Ceri Perkins is a New York City-based writer and editor who covers the environment, science, nature and human behaviour. As a freelancer, she has lived around the world, from Madrid to the Scottish Highlands. Before going freelance, Ceri was based in Geneva, Switzerland, as a staff writer/editor at CERN, home of the Large Hadron Collider. Later, she was News Editor at NYC-based magazine Spectrum, where she edited news and opinion stories about the neuroscience and genetic underpinnings of autism. In her spare time, Ceri is typically either outdoors in nature or curled up inside with a stack of books and a pile of things to make or fix. She holds a Bachelor’s in Atmospheric Science, a Master's in Science Communication, and you can read her work in TED Ideas, BBC Earth, The Guardian, Physics World, New Scientist, and more.