The Truth on the Benefits of House Plants
And how they don’t really clean the air inside your home but may be harming you.
I love plants. Those close to me know my passion in such matters. A crazed obsession of wild outdoor plants and gardens. And a mild obsession with having indoor greenery. Many people approach me and ask "what would grow best here?” Usually showing me a photo of their space. Normally the intention is to beautify their home and to increase air quality during this time of being indoors, a lot (referring to self isolation during the COVID-19 pandemic for those future readers). But what if I told you there is no way your home air quality is improved by having a gorgeous and expensive monstera deliciosa to look at.
It all started with a 1989 study by a NASA scientist of Bill Wolverton (1). Every major plant blog will reference this study when telling you house plants purify the air in your home. (Lies). The study looked into VOCs (volatile organic compounds), which are harmful gases that come from many materials, solvents and products used everyday. Some common examples being building materials, paints, nail polish and remover, cleaning products, car emissions and even chlorinated water. Basically if it has a strong artificial smell, it is likely to have harmful VOCs. The NASA study was to look at how to remove these from spacecrafts crafted from new materials that produce VOCs. Plants. Plants came to the rescue. They were effective at removing these, in a closed chamber. Remember this was a scientific study, that has to get rid of variables/conflicting factors. And it wasn’t the last scientific study. There are many articles on NCBI (190+ studies) that go over these such as this one and my favourite and newest one here.
Now the problem is, we do not live in small closed chambers. Yes, it may feel like you do when you are in a 400 sqft condo in downtown Toronto, self isolating, but it is not a closed chamber. Our home environments are dynamic. We open windows, there are drafts coming through the walls, our homes are ventilated and we constantly bring in new things into our spaces. The moment you open your window, the negligible amount of purification your indoor plants did is out the window (puns totally intended). In fact, for there to be even a tiny noticeable difference in air quality due to your plants, you would have to have a medium sized VOC filtering plant every square foot (2). In a 400 sqft apartment that is 400 green bundles of joy, which brings about another problem.
Plant soils have microbes in them naturally. Some of which are completely harmless and some that can affect your health in various ways. If you over-water your plants, it increases the chances of growing mold due to root rot. And when you have many plants in your home the humidity increases, further creating an environment for mold. This can bring about lung and skin symptoms that can lead to harmful health conditions with long-term exposure. Wiping your plants and changing the soil every 6 months to a year greatly reduces those chances. This also provides new nutrients to your plant babies and allows them to grow more if re-potted into a larger container. But! This by no means is to encourage you to get rid of all your plants or not but any. Mold and bacteria grow due to negligence and overwatering. Otherwise indoor plants have amazing benefits!
1) A boost to your mood.
The color green has been shown to reduce depression and anger, while creating some serenity in your home (3). Having beautiful healthy plants around you creates a visually appealing environment. People are found to be less stressed in well decorated homes with lots of color and vegetation versus a plain monochrome room. And interacting with your plants by means of trimming, watering, repotting, is also shown to reduce stress (4).
2) Creating a sense of responsibility.
This can go either way. But for some having something living to be responsible over creates some simple meaning in their lives. You feel more fulfilled and happy. It allows for one to be excited when a new leaf grows or your plant blooms. Conversely, if you allow your plants to die, then you may experience some negative emotions.
3) Reduction of stress in high-stress environments or situations.
Perceived attractiveness of an environment has it’s benefits. A small study was done in a healthcare setting where it was seen that those with a new health diagnosis felt less stressed when exposed to an environment filled with plants (5). So not only in your homes, but plants are important in a clinical setting if you see clients/patients.
4) Creating a more diverse indoor microbiome.
This is a newer concept that still needs more investigation. But similar to the hygiene hypothesis, (where being too cleanly as a child stunts the development of your immune system) there has been some research that plants can bring more microbial diversity into your environment (6). This allows for our bodies to react to different types of bacteria and microorganisms, in turn being able to train our immune system to recognize a larger variety of invaders. BUT, this can easily be done by just opening your window… Plus, there are so many factors that go into this theory.
5) Our connection to nature.
No specific research here. This is just instinct. We as humans have bonded and evolved with nature. There is a deep inset connection there regardless of you being a city or country type person. From culture, food, medicines, fashion and so much more, plants are healing and very important. Just as a person being disconnected from community/friends is more likely to develop low mood and mental health issues, a person disconnected from nature will be seen to have that affect as well.
Having some greenery in your home is important, but possibly not in the ways you thought! Happy Earth Day and I hope you get to appreciate some form of nature today! As we are all self isolating maybe it’s time to order some plant babies and start making your home more green.
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References:
1) Wolverton BC, et al. “Interior Landscape Plants for Indoor Air Pollution Abatement.” Final Report––September 15, 1989. Stennis Space Center, MS:Science and Technology Laboratory, John C. Stennis Space Center, National Aeronautics and Space Administration (1989). Available: http://tinyurl.com/39cz3ju
2) Cummings B.E., Waring M.S. “Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies.” J Expo Sci Environ Epidemiol. 30, 253-261 (2020). https://doi.org/10.1038/s41370-019-0175-9
3) Briki W, Majed L. “Adaptive Effects of Seeing Green Environment on Psychophysiological Parameters When Walking or Running.” Front Psychol. 2019;10:252. Published 2019 Feb 12. doi:10.3389/fpsyg.2019.00252
4) Lee MS, Lee J, Park BJ, Miyazaki Y. “Interaction with indoor plants may reduce psychological and physiological stress by suppressing autonomic nervous system activity in young adults: a randomized crossover study.” J Physiol Anthropol. 2015;34(1):21. Published 2015 Apr 28. doi:10.1186/s40101-015-0060-8
5) Dijkstra K. et al. “Stress-reducing effects of indoor plants in the built healthcare environment: the mediating role of perceived attractiveness.” Prev Med. 2008 Sep;47(3):279-83. doi: 10.1016/j.ypmed.2008.01.013.
6) Berg G, Mahnert A, Moissl-Eichinger C. “Beneficial effects of plant-associated microbes on indoor microbiomes and human health?” Front Microbiol. 2014;5:15. Published 2014 Jan 29. doi:10.3389/fmicb.2014.00015