Read any new-wave article on snake plants or ivy or other ‘super plants’ and they are laden with claims of air purification benefits, often citing a 1989 study by NASA. That sounds great in theory. However, many of these articles also go on to talk about other heady, wellness nonsense, like fucking feng shui, which should tell you all you need to know about the thoroughness of their research. There’s not many NASA studies on feng shui… ”the study concludes that placing the Global Navigation Satellite System opposite the ranging LIDAR sensors will give you good luck in finding your way to the Mars”
A small cross section of the typical misleading claims
It’s a nice thought, that you can buy some plants and they will purify your air. Obviously everyone knows that plants produce oxygen from CO2. They also do remove other volatile organic compounds (VOCs) – which was the focus of the old NASA study.
Yes, the NASA study was an interesting one, and showed that snake plants can remove a significant amount of VOCs like Benzene and Formaldyhyde from… a ‘sealed experimental chamber’. Unfortunately, we do not live in sealed experimental chambers – which is one problem with articles that cite these claims, and then change them to simply ‘snake plants etc. will purify your air’. Let’s have a deep dive into two of the main claims. 1. These plants will significantly reduce CO2 levels in your home 2. These plants purify your air from harmful VOCs – improving health.
Do Plants Purge Your Home of CO2?
Dr Tijana Blanusa, speaking to Which last year on the same subject concluded:
“Over the last few years, there was much scientific investigation around the impact of houseplants on indoor air quality, particularly on their ability to remove CO2 and volatile organic compounds (VOCs) e.g. emitted from paints and furnishings, to name some sources,” explains Dr Blanusa.
“Scales of study differed – from individual plant to room scale. Results to date suggest that due to typically low light levels indoors the contribution of individual plants to the removal of these compounds is relatively low and that either higher light levels or larger numbers of plants are required to elicit an effect.”
Dr Tijana sounds like she knows what she’s talking about, so lets have a look at one of her most recent studies. This study, from 2018, measured differing light levels on an indoor plants ability to lower CO2 in a room and concluded, in part, that:
At ‘no’ and ‘low’ indoor light, houseplants increased the CO2 concentration in both substrates; respiration rates, however, were deemed negligible in terms of the contribution to a room-level concentration”
However, the corn plant, in a certain substrate in the experiment showed more CO2 removing ability when exposed to high light levels (which presumably supercharged it’s CO2 removing ability):
In ‘very high’ light, D. fragrans, in substrate 2, showed potential to reduce CO2 to a near-ambient (600 ppm) concentration in a shorter timeframe (12 h, e.g. overnight).
So, ultimately as Dr Tijana showed, in order to see significant differences in CO2 in your home using plants you will need to carefully match the substrate with the plant species, and have incredibly high light levels – ‘very high’ in the above study was an eye-melting 22,000 lux! To get some perspective on lux levels, a typical room in your home, in daylight, is a mere 300 lux; a floodtlit football pitch is 700-16.000 lux, and an average overcast summers day around 30,000 lux. So, ultimately if you want to significant lower the level of CO2 from your home, then you would need an elaborate and un-realistic level of light to blast your numerous, large, house plants.
The corn plant Dracaena fragrans
But what about Volatile Organic Compounds?
Let’s nail the coffin lid on this myth totally, we get a perverse pleasure from doing so. Michael Waring, an environmental engineer and indoor air quality expert (not ‘blogger’ or ‘yoga teacher’) and his colleagues did a review of several studies which claimed, in layman’s, that plants can purify your air of VOCs. Top tip: When you’re researching any topic, look for these kind of literature reviews, they often put the subject into perspective. Waring and colleagues took the results of the studies, and scaled them up to a typical home environment – using all kids of maths and VOC ratios etc. Talking to National Geographic on the topic in 2019, Waring skewers the myth:
To reduce VOCs enough to impact air quality would require around 10 plants per square foot. In a small 500-square foot apartment, that’s 5,000 plants, a veritable forest.
Suddenly our Turn Your Living Space Into a Jungle article isn’t such a bad idea after all. Lets visualize that, the below woman, which the nypost wrote about, in her 447 foot apartment in Brooklyn, has a puny 1100 plants. Just another 4000 and she will have the cleanest air in Brooklyn.
Well, we hope that clears up some myths about house plants, you can now have fun destroying your friends when they make this claim about their small snake plant on the shelf. Click on our Plants tag on the right hand scroll bar for some more articles on plants.
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