Air-purifying houseplants is a popular and frequently searched for item and there are a plethora of articles and lists designed to tell you all the air-cleaning benefits of certain plants. Perhaps you've seen them?
“Top 10 Best Air Purifying Plants to Buy for Your Home!”
“Boost Your Home’s Air Quality with These 15 Air Purifying Plants!”
“Never Open Your Windows Again With These 6 Air Purifying Plants!”
There are many articles on plant blogs- and, most importantly plant store websites- that make the claim that there are certain plants you should purchase to help you clean your indoor air at home and at work of common household toxins.
It sounds like it should be true. It sounds like it makes sense. Plants have been scientifically proven to clean some toxins from surrounding air- right? The answer is yes, they have- just in very small and controlled laboratory settings.
The idea that certain plants work to purify the air in homes and other spaces came from a 1989 experiment done by NASA. They were looking for ways to filter out harmful air pollutants in space stations and came to the conclusion that plants could remove cancer-causing chemicals from the air.
They conducted their experiments by placing certain plants in a two-foot wide by two-foot long container and using a fan to circulate volatile organic compounds (VOC’s) throughout that space. The plants were able to filter these volatile compounds in these small, airtight containers- sometimes in a matter of hours.
But we don’t live in small, airtight containers. Our living spaces and work environments are larger than two feet long by two feet wide, and they are certainly not airtight. The reason that this conception that plants clean indoor spaces of common toxins is a myth is that the data used from one study done in a very controlled and small laboratory setting was then assumed to have the same results when applied in our not-so-controlled and much larger home or office setting. It's a cautionary tale of how scientific research and findings can be misunderstood or misinterpreted.
Michael Waring, PhD and one of his doctorate students Bryan Cummings, reviewed over 30 years of research into plant air purification properties and published their findings in the Journal of Exposure Science and Environmental Epidemiology in 2019. The associate professor of architectural and environmental engineering at Drexel’s College of Engineering in Philadelphia and his student came to the conclusion that “natural or ventilation air exchange rates” do most of the air purifying and at a much faster rate than houseplants ever could.
Waring was able to calculate just how many plants you would need to have in your home or office in order for them to purify the air better and faster than the natural and artificial ventilation systems already present. Using a calculation known as the clean air delivery rate (CADR), Waring found that you would need 10 plants per square foot in order to remove VOCs at a rate that would actually raise indoor air quality. That means if you live in an 882-square-foot apartment, you would need close to 9,000 plants in order to significantly and positively affect your indoor air quality.
Now, I love plants as much as the next plant owner and will be the first to admit that I am constantly growing my plant collection at every chance/excuse that I can. And it is because I have this love for my plants that I can say with confidence that I could never keep so many in my home nor care for such a large quantity properly. Not to mention I would probably have nowhere to sleep, sit, cook, and I may never see my cat ever again in such a jungle.
While our houseplants may not purify the air in our homes at the extent or rate that we might have thought they did- they still host a wide range of benefits to us that have been scientifically proven and can be confidently shouted from the rooftops. Studies show that having and caring for plants in our homes and workspaces can help reduce anxiety and stress, decrease depression, and even enhance our memories and boost our creativity and life satisfaction. That's a pretty great return for investing our time and care into our little green plant friends.
So keep collecting houseplants and keep caring for them and reap those good feeling benefits. Plants already do so much for us just by teaching us how to care for another living thing. Just don’t fall prey to the articles pushing certain plants to rid your home of common household toxins- only an air purifier can do that.