So just stop with the claims. I thought this—well, let’s call it an exaggeration rather than a myth—had died down, but no. It cropped up in a recent enewsletter from a source I’d have thought knew better: the National Garden Bureau. Yes, the NGB is all about marketing, but it generally sticks with announcing All-America Selections, promoting the work of longtime gardening experts, surveying gardeners, and so on. Mind you, the word “might” was used, but that came after “And we all know they can help ‘clear the air.’” This is by no means a forthright statement that plants do any true air cleaning and it wasn’t meant to be.
The people at NGB know just as well as most of us that a 1989 NASA study about plants cleaning volatile organic compounds (VOCs) from interior spaces has been found to be fine as far as it went, but its conditions were far from that to be found in any home. As this article notes, “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.”
I know there are a lot of fanatical houseplant collectors out there, but that number sounds a bit high. Full disclosure: I bought into all the air-cleaning at one point myself, until I saw better data.
I could cite studies about this all day long—here’s the one the NatGeo article I mentioned above uses—but that’s not the point. At all. Houseplants are wonderful. A boatload of positive arguments can be made that have nothing to do with air-cleaning. They provide beauty and softening effects to interior spaces. To some degree, they bring nature inside. Many of them even make rooms smell nicer, as the tulips I’m forcing in my dining room (at top) do. Though I won’t claim psychological benefits for all—those studies exist as well—I know they make me feel happier.
We don’t need to oversell houseplants.
AMEN! I’m very disgruntled with marketing gimmicks in the green world. I’d like to think we are “better than that”. Just resisting an urge to get involved with a Facebook post concerning “plants that repel mosquitoes”! I’d say half of the 173 comments so far believe they do.
Don’t do that! You’ll get hate mail! People believe what they want to believe, regardless of whether there is scientific fact.
Agreed! This cleaning the air business should be recognised as an exaggeration. I’m noticing that the claims made for plants and gardens since the pandemic have become inflated. Is it not enough that it makes us happy and pleasantly occupied? I have a knee jerk reaction to anything touted as good for me
Hi Elizabeth! Thank you for referencing our latest blog on houseplants. The focus of the blog in reference is 95% about the emotional and psychological benefits of plants in the workplace. It starts by referencing the Japanese study on reducing stress. Then the Australian study talks about reducing depression, anxiety and anger. Then that Vermont study summarized several other studies that showed how plants in the workplace can enhance productivity and creativity.
That led to the paragraph about reducing toxins and yes, that NASA study has some flaws. That is exactly why we added the word “might” to the author’s original post. Mainly, this blog was written to talk about all the good things houseplants can do for stress, anxiety, depression, etc. Those two sentences are not there to be any sort of marketing gimmick. We can all use more positive inputs in our lives and houseplants are just one way to get that. 🙂
Hi Diane, I deliberately cited that “might” and I acknowledge that the air cleaning was not a central focus. But I posted because I think the whole thing should be dispensed with -entirely- until we have better data showing benefits for homeowners. Thanks for the important work of NBG!
Diane – thanks a lot for sharing the true context and spirit of the referenced NBG blog post! I fully agree that having plants in the workplace can be an enormous mood booster. I used to have an entire large windowsill packed with unusual flowering plants and cacti in a research lab I used to work in…until a committee came through one day and made me remove them because of the potential for “contamination”. It was pretty discouraging and to this day, I’m not convinced their concerns were scientifically valid…but it was a beautiful workplace garden that many enjoyed while it lasted :-).
Diane: But including the myth about cleaning the air then makes the reader question the rest of the article.
Did I read somewhere that it is not actually the plant that has any effect whatsoever on air quality but the pot of soil? And that was in a very small controlled environment (ie box). Not to start another urban myth that has us putting trays of soil around our homes. Although possibly my seed trays on my dining room table are a start?
Do litter boxes count as soil? Snort.
Only if you use dirt for the litter! snort, snort!
Natural soil has beneficial microbes that have been shown to be good for human’s serotonin levels, and breathing certain microbes can be good for gut health, but not for “cleaning the air” on any appreciable level for a single plant.
I was taught in a course on tropical plants many decades ago, (yes, that long ago – around 1989-90) that it’s actually the roots of plants that are supposed to do the cleaning of the air. That’s the only place I’ve seen that information. I don’t remember what the source of the information was that the teacher quoted. But roots are in the soil (Except, of course, when they’re in the air, lol).