New studies are always coming out to contradict popular wisdom and old wives’ tales. Recently, those studies are taking aim at houseplants. Thanks to new research, a bundle of new articles are re-examining the old claim that houseplants clean air pollution.
If you like houseplants, you’ve probably seen the list of NASA-backed air-purifying plants at least once or twice online. Monstera deliciosa, snake plants, and philodendrons top the list of air-clearing greenery.
But some people challenge this study and its findings, saying that houseplants don’t do anything to help. Who’s right? What’s the truth? Let’s clear the air.
The list of environment-healing plants started making the rounds back before the internet existed to give it wings. It began with a 1989 study by NASA scientist Bill Wolverton titled Interior Landscape Plants For Air Pollution Abatement.
Wolverton’s study claimed that plants had a lot of promise when it came to removing toxins from closed environments. Some plants, like golden pothos and Boston fern, performed better in the study than others.
Those high-performance plants made it onto dozens of lists, which eventually spread out to the far corners of the internet. Houseplant aficionados like you and I hunted down these super plants and filled our houses with them.
Now the naysayers are claiming it was all for nothing and our beautiful, purifying plants aren’t doing as much as we thought they did. So what’s true, and what isn’t? Do houseplants really clean the air, or is this just one more hippie dream gone sour?
Let’s take a look.
Toxins in the Air
One of the problems with studies is that each one is looking at something slightly different. Each study is funded by different people, all of them pursuing different goals. Since they’re all approaching things from different perspectives, it can be hard to tell who’s right.
Wolverton’s original study wasn’t actually interested in whether my sole snake plant will freshen the air in my drafty little yurt. He was looking into the usefulness of plants in closed, contained systems and their effect on VOCs, or Volatile Organic Compounds.
He worked for NASA, after all, so he was primarily thinking about spaceships and how humans could survive on other planets. What he found gave him hope.
In a closed system, with little to clutter things up, many plants impressed Wolverton with their purification abilities. He was so impressed that he later published a book listing the “50 Houseplants that Purify your Home or Office.” It looks as though air purifying plants were a passion for Wolverton.
Hippie homemakers and minimalist millennials embraced Wolverton’s suggestions and filled their spaces with the recommended plants. After all, we’re learning that almost all of our cleaning supplies, fragrances, and accessories are toxic – we wanted to do something to keep pollution at bay. Wolverton’s words gave us hope that we could change our world.
And Wolverton wasn’t wrong. His work was just misinterpreted.
He later founded Wolverton Environmental and developed a planter that allows more air to circulate around the roots of plants. He found that a houseplant’s ability to clean air pollution increased the more air was allowed to reach the roots.
New researchers don’t deny that houseplants can clean air pollution, they just claim that the benefits are minuscule. Apparently, a few negative nancies in the scientific community re-analyzed the studies surrounding houseplants and came up with some seemingly hope-crushing conclusions.
For instance, researchers published an article in the journal Journal of Exposure Science & Environmental Epidemiology titled “Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies.”
It concludes that while plants can remove VOCs, they aren’t effective in the real world.
The truth is, these new studies don’t overturn Wolverton’s research at all. Wolverton’s study is still considered to be accurate. Instead, they merely temper the enthusiasm that his research inspired by people who misunderstood the information.
Can Plants Clean the Air?
Even the newest studies don’t pretend houseplants do nothing for air quality. If you look at things other than VOCs, the results are even more promising.
Take a recent study in Air Quality, Atmosphere, and Health. It concludes that “potted plants offer clear potential to improve indoor air quality—in particular in confined indoor spaces that are poorly ventilated and/or located in highly polluted areas.”
To be clear, the effect we want to see from our houseplants is a lot greater than the actual effect. Essentially, unless your house is chock-full of the most cleansing plants, their influence on your air is probably negligible.
Why? Well, our homes are too cluttered with mitigating factors. Open windows, air conditioning, thousands of square feet of surface area – what plant wouldn’t get overwhelmed?
It’s a bit unfair of us to expect a couple of snake houseplants to remove all the air pollution in the whole place. New air is constantly moving in and out of the house. We’re burning heavily fragranced scented candles and look at all that brand-new stuff from Hobby Lobby!
Our clutter – not to mention polluted air from the AC or the attached garage – is continually off-gassing into the house.
Expecting a bunch of houseplants to make a noticeable difference in all that air is a bit like inviting one, exhausted cleaning lady to come once a month and keep up on the mess your frat house makes each day.
The research says it could take up to 1,000 plants in a 10×10 foot room to make a measurable difference in air quality. Those of us trying to squeeze 20 houseplants into a tiny house or small apartment know just how impractical it can be to bring more plants into the house.
So what’s a houseplant enthusiast to do?
Air Quality, Humidity, and Oxygen
Stop worrying! While houseplants may not pull as much pollution from the air as we might like, they still contribute greatly to overall air quality. Houseplants do freshen the air. They raise humidity levels – which can improve immunity, especially during the dry, winter months.
Plants also breathe in CO2 and exhale oxygen. Even small, consistent increases in indoor oxygen levels can improve general air quality. So while your houseplant may only be pulling tiny amounts of toxins from the air, they’re still doing their best to boost the quality and breathability of that air.
The Benefits of Houseplants
Whether you’d hoped to remove air pollution or not, if you’re growing houseplants, you’ll need to use some caution.
First of all, remember: there’s a difference between measurable air quality and experienced air quality. Houseplants may not contribute much to the former, but they undoubtedly improve the latter.
Research shows that people are calmer, happier, and less depressed when living with plants. Houseplants improve our experience of our environment – and that produces real, measurable benefits in our own bodies.
If you bought a few rubber plants to balance out your pack-a-day smoking habit, then you might be disappointed by the results. But for the rest of us, houseplants offer a host of honest-to-goodness life improvements.
Whether you’re gardening outdoors or tending your monstera in a skyrise apartment, time with living flora reduces stress and anxiety. Long-term living with plants can even reduce blood pressure and suppress your fight-or-flight reactions.
A 2015 study showed measurable improvements in stress levels for people tending to and looking at plants on a daily basis. So if you do work in a high-stress, corporate environment – filling your office or cubicle with indoor plants could improve your stress levels and help your coworkers chill out a bit too.
2. Ease Depressive Symptoms
Depression isn’t something that can be fixed by adding a few plants to your bedroom. But studies show that people suffering from depression experience increased feelings of balance and well-being when living with houseplants.
Now, don’t go out and tell your daughter she just needs an aloe plant and she’ll feel ok again. That’s not going to work. Instead, try giving plants as housewarming gifts – a cheerful, little spider plant is a great way to say “I love you, and I’m here for you.”
3. Memory Boosting
Unsurprisingly, given the relationship between stress and memory loss, studies have shown that time with plants improves short-term memory. Our cortisol levels can have a huge impact on memory – and the calmer we are, the easier it is to remember things.
Plants often have the opposite effect. When dementia patients spend time with plants, there’s often a measurable improvement in short-term memory.
This can end up creating a positive cycle of peace, success, and confidence that can make life so much easier for those struggling with short-term memory loss and their caregivers.
4. Rapid Recovery
One of the most interesting studies looked at the impact of plants on healing and recovery. According to the research, people who spent much of their recovery time looking at plants healed faster from surgery, illness, or injury.
Patients who had the opportunity to spend time with plants spent less time in the hospital than people without plants in view.
5. Creative Companions
There’s a reason so many artists like to fill their homes and studios with houseplants! Studies have consistently shown that we’re more creative with plants nearby. Houseplants increase productivity and help our brains make connections quicker than we do without our green companions.
Not only do plants make your house more beautiful, but they also help you to appreciate and create beauty as well.
A Note on Safety
Not all houseplants are ideal for all situations. Some houseplants are not safe for pets or small children to live with. Plants are fascinating – sometimes they’re so fascinating a child just can’t resist tasting a leaf or two. Other plants give off a sweet aroma that can lure in a cat or dog.
Use caution when picking the right plant for your house. If you have pets that like to sample everything or a toddler who wants to do the same, pick safe, non-toxic varieties.
Avoid popular toxic plants like poinsettia and mistletoe, tread lightly with plants like aloe, which have a strong, laxative effect, and keep all the plants you’re unsure of out of reach.
I like to hang a lot of my risky houseplants high out of reach. Tall shelves or tall, stand-along planters are good options as well.