Well… No.
And it is true that this is a myth a lot of us wish hadn’t been debunked.
However, you must have noticed that most search results that come up on the Internet offer diametrically opposite views of the topic, and assure us this or that plant will improve air quality in our home while also making it prettier and nicer to live in.
But, this actually isn’t true, and if you want to learn why – keep reading!
The NASA Study
Almost all articles and blog posts out there rely on a study done by NASA in 1989.
It attempted to research whether plants can reduce VOC (volatile organic compounds) in sealed chambers, such as space stations.
People sent to space had to spend prolonged periods of time in tightly sealed environments, so indoor air pollution problems would be caused by the toxins emitted by materials and also man’s own waste products.
The solution NASA proposed was to bring plants into those environments.
Plants they used in the experiment were:
- Bamboo palm (Chamaedorea seifritzii)
- Chinese evergreen (Aglaonema modestum)
- English ivy (Hedera helix)
- Ficus (Ficus benjamina)
- Gerbera daisy (Gerbera jamesonii)
- Janet Craig (Dracaena deremensis)
- Marginata (Dracaena marginata)
- Mass cane/Corn cane (Dracaena massangeana)
- Mother-in-law’s tongue (Sansevieria laurentii)
- Peace lily (Spathiphyllum)
- Pot mum Chrysanthemum morifolium
- Warneckei (Dracaena deremensis)
Those are more or less the exact same plants that bloggers and Youtubers now promote as must have air purifying plants.
The conclusion of the study was:
Low-light-requiring houseplants have demonstrated the potential for improving indoor air quality by removing trace organic pollutants from the air in energy-efficient buildings.
page 18 of the NASA study
Now, if you haven’t read the study yourself you will find this conclusion very exciting.
But if you did, you likely would not have missed this part that states:
The plant root-soil zone appears to be the most effective area for removing volatile organic chemicals.
Therefore, maximizing air exposure to the plant root-soil area should be considered when placing plants in buildings for best air filtration.
page 18 of the NASA study
That means that ANY plant can “purify air”, and also that the microbes in the potting soil did the majority of the air purifying, not the leaves of the plants.
They found that the soil without any sort of plant had better results in purifying air than the fully leafed plant.
Other Shortcomings of the NASA Study
In the NASA study they placed the plants in chambers just over two feet wide and long and filled them with three chemicals (benzene, trichloroethylene (TCE) and formaldehyde) circulated by a small fan.
Let’s not forget, other than the three tested by NASA, there are hundreds of other pollutants in our modern homes.
They too need to be tested to make this kind of experiment relevant to a domestic household.
The evidence was conclusive that the plants absorbed these pollutants, but in airtight chambers, which is far from a realistic household environment where the outside air is exchanged with the air inside.
That wasn’t taken into consideration at all in the NASA study simply because they didn’t need to – there is no exchange of air on space stations.
So, in fact, that means that the NASA study is completely irrelevant to a normal modern household.
John Girman, former senior science adviser at The U.S. Environmental Protection Agency’s Indoor Air Division, says a 1,500-square-foot house would need 680 plants to duplicate NASA-like benefits, and the result would be an indoor jungle with moisture problems.
In his study Critical Review: How Well Do House Plants Perform as Indoor Air Cleaners? Girman lists several field studies that all concluded that the reduction of VOC by plants was not statistically significant.
He says that even though the pollutant reduction by plants in chamber studies seems remarkable, closer examination suggests otherwise.
According to him the claim that 90% of pollutants in a chamber can be removed in a 24 hour period through plants was proven to be less effective than the removal achieved by the natural ventilation rate of a very tight house.
Also it is important to state that for every pollutant that was absorbed in the beginning, a part of it was released back into the atmosphere after some time.
This is referred to as off-gassing. So, not only do the materials and humans emit VOC, plants themselves do it as well.
Causes of Indoor Air Pollution
Unaware of it, we introduce a variety of toxins into our home, making indoor air pollution a real concern for our health and the environment.
Even while not all of them are highly dangerous, exposure to high amounts might trigger allergic reactions or dizziness.
People living in cities spend about 90% of time indoors, according to The U.S. Environmental Protection Agency.
The time spent inside exposes us to indoor air pollution that can have many sources:
- Furnishings
- Carpets
- Buildings with poor ventilation
- Upholstery
- Tobacco smoke
- High levels of dust
- Dry-cleaned clothing
- Formaldehyde (mostly found in wood furniture and floors)
- Paint
- Ozone from the use of printers and fax machines
- Synthetic building materials
- Chemicals from cleaning products
- Pesticides
- Bacteria
- The presence of mold and/or fungus
- Outdoor pollution that enters
According to the EPA, levels of VOCs are typically two to five times higher inside than outside.
We are all exposed to some amount of indoor air pollution, and in some cases when ventilation is bad, or for people who may be highly sensitive, it can make you feel sick.
Headaches, nausea and fatigue are some of the symptoms of the sick building syndrome.
To reduce this possibility to minimum:
- Use cleaning products with low fumes and no fragrances
- Vacuum regularly to remove dust
- Spend as much time outdoors as you can
- Change out air filters every couple of months (or more, if necessary)
- Get a test for possible indoor mold or fungus
- Update computer monitors and other display systems
- Use ventilation when cooking
- Avoid open grilling and even wood-burning fires
- Open windows to improve natural air circulation
- Look for paints with low VOC ratings
- Look for carpeting or furniture made from natural materials
- Pay special attention to ratings for formaldehyde, styrene, 4-PC and VOCs.
Does this then imply that you shouldn’t bother with using houseplants to purify the air in your home at all? Not exactly.
Even though a few houseplants on their own won’t do much to purify the air, they still have a lot of other benefits that make them worth keeping.
Benefits of Indoor Plants (Whether They Do Purify Air Or Not)
It has been shown that having indoor plants greatly lowers stress levels.
Furthermore, they are beneficial to persons suffering from anxiety and depression, and so plants are now being prescribed to individuals with depression or anxiety by medical clinics in Manchester, England.
Employees who are surrounded by natural elements at work, such as indoor plants and sunshine, report much higher levels of satisfaction with their jobs and commitment to the companies.
This information may make CEOs and managers happy. Some of them are also utilized as humidity-absorbing plants, lowering the likelihood of mold growth.
Here is a list of benefits of indoor plants:
- Increase oxygen content in the room
- Maintain humidity levels in a room
- Maintain temperature in a room
- Reduce carbon dioxide
- Remove certain pollutants from the air
- Reduce dust from the air
Just to make it clear, according to Michael Waring plants are technically removing a minute amount of airborne toxins, but, “to have it compete with air exchange, you would need an infeasible amount of plants”, he says.
Meaning – we cannot use plants as air purifiers indoors, but good ventilation will do the trick.
However, you should still go out and buy plants.
They make our homes prettier, are fun, make us happy and improve our overall well being.
If you want to breathe cleaner air then going outside and taking a walk in a park or a hiking trail is a thousand times better.
And don’t forget to air out your office and house! 😉