Most people are aware of the fact that our home is full of toxins, thanks to research and reports we constantly see on the news. A lot of those toxins are in the air that we breathe inside our homes. One of those is formaldehyde, a dangerous chemical that’s being off-gassed from things like laminate flooring, insulation, paints, cleaning supplies and furniture, among other things.
(Formaldehyde belongs to a group of chemicals called volatile organic compounds, or VOCs. For more information about VOCs and other chemicals that affect indoor air quality and to learn more about off-gassing, read this post.)
Formaldehyde can have varying effects on our health, depending on the level of exposure. It could be as mild as itchy eyes or skin, coughing, or nose and throat irritation. But it can also be far more serious since formaldehyde has been labeled as a Group 1 carcinogen.
But how exactly do you remove formaldehyde from your home?
There are many ways to go about it, but one of the least expensive is to use plants. In this post, we’ll talk about just how plants remove formaldehyde and what the best plants to remove formaldehyde are.
How Plants Remove Formaldehyde
Formaldehyde is broken down within 10 minutes of entering a plant. The plant utilizes specific pathways within the broader process of photorespiration to achieve this (one-carbon metabolism and the Calvin cycle).
In simple terms, the formaldehyde is broken down and converted into sugars while creating energy for the plant to use.
The reaction occurs both when formaldehyde enters the plant through the leaves and roots, so there are two ways technically that a plant could remove formaldehyde.
Plants also break down formaldehyde at a faster rate when under stress. In other words, the more formaldehyde that there is in a room, the faster the plant can break it down. This is great news for newly built homes where new building materials are off-gassing VOCs at higher concentrations.
However, this doesn’t mean that a small plant will be able to fend off all the formaldehyde that’s in a room. You may need several plants to see results that move the needle. You may also wish to introduce a simple air quality monitor to your home to gauge just how effective the houseplants in your home are at reducing formaldehyde levels.
By the way, air quality monitors may display formaldehyde differently on the screen. Formaldehyde could either be measured by itself but is displayed as HCHO (its formula), or it could be displayed as a summarized reading with a group of other commonly found VOCs as a total VOC reading (TVOC).
What’s a Safe Level of Formaldehyde Inside a Home?
You can’t try to reduce the levels of formaldehyde if you don’t know what to aim for. Air quality monitor in hand, it’s best to test first before introducing any plants to get a baseline reading. The air inside our homes tends to have more formaldehyde than outside air.
The EPA has stated that the average typical formaldehyde reading of indoor air is 0.10 to 3.68 parts per million (ppm). It could be higher in newly built homes where fresh paint, insulation, and flooring are off-gassing at higher rates. It could also be higher in older homes, as building materials in the past tend to have been manufactured with higher levels of VOCs.
So what’s an acceptable level of formaldehyde to aim for in your home?
California’s government is one of the leaders when it comes to setting standards for indoor air quality. California’s own EPA recommends a limit of 27 ppb (parts per billion) of indoor air overall. Although, it’s wise to aim for lower levels since this recommendation assumes an 8-hour interim exposure level. Note that your air quality monitor may give you a formaldehyde reading in mg/m³, so you may need to do a simple conversion.
The Best Plants to Remove Formaldehyde
I’m sure you probably want to know which plants are best at removing formaldehyde from indoor air. Based on some of the recent research papers, here’s a list of some plants that performed exceptionally well.
NASA’s Clean Air Study
According to Dr. Wolverton’s study for NASA, there are plenty of houseplants that can remove formaldehyde from the air. The following are the findings, although they must be interpreted carefully. While the air in our homes is cycled several times per hour and is subject to various effects, the experiments of the majority of these kinds of studies are performed in closed, controlled chambers.
Another thing to consider is also the size of the plant. While some plants may be able to remove quite a large amount of formaldehyde, another plant that takes up less space in your home may be just as effective. It’s also worthwhile to note that some of these plants come from tropical climates and may be difficult to maintain in colder climates with less filtered sunlight.
It’s also a good idea to look at how the plants were potted and replicate that. Plants that use activated carbon and ventilation inside the potted soil tend to be a lot more effective at eliminating toxins. A lot more!
Having said that, here are some of the NASA findings.
- Bamboo palm, removed 3,196 µg of formaldehyde per hour.
- Boston fern, removed 1,863 µg of formaldehyde per hour.
- Florist’s chrysanthemum, removed 1,450 µg of formaldehyde per hour.
- Dwarf date palm, removed 1,385 µg of formaldehyde per hour.
- Kimberley queen fern, removed 1,328 µg of formaldehyde per hour.
- Variegated snake plant, removed 1,304 µg of formaldehyde per hour.
- English ivy, removed 1120 µg of formaldehyde per hour.
- Weeping fig, removed 940 µg of formaldehyde per hour.
- Areca palm, removed 938 µg of formaldehyde per hour.
- Cornstalk dracaena, removed 938 µg of formaldehyde per hour.
- Lady palm, removed 876 µg of formaldehyde per hour.
- Red-edged dracaena, removed 853 µg of formaldehyde per hour.
- Warneckei, removed 760 µg of formaldehyde per hour.
- Peace lily, removed 674 µg of formaldehyde per hour.
- Spider plant, removed 560 µg of formaldehyde per hour.
- Banana, removed 488 µg of formaldehyde per hour.
- Elephant ear philodendron, removed 416 µg of formaldehyde per hour.
- Selloum philodendron, removed 361 µg of formaldehyde per hour.
- Variegated philodendron, removed 353 µg of formaldehyde per hour.
The study especially singles out the Boston fern and Lady palm not only for their ability to remove formaldehyde, but to actually improve formaldehyde levels over time.
More Recent Studies
Since the NASA studies were generally done between 1986 and 1989, it’s important to compare them to today’s studies. After all, a lot has changed since then, from the technology to the building materials in our homes.
In a 2011 study, four commonly found household plants were tested for formaldehyde removal. Using activated carbon in the soil (just like NASA did), the 2011 study found that all four plants were able to remove 90% of formaldehyde within 24 hours. Even though this study was done using a closed chamber system, its results are still impressive and should be able to improve the air in a real-world home environment.
The four plants studied were:
- English ivy.
- Florist’s chrysanthemum (also known as garden mum or pot mum).
- Dumb cane plant.
- Devil’s ivy (also known as gold pothos).
In another study from 2008, the Japanese fatsia and weeping fig were tested for their ability to remove formaldehyde. The researchers found that on average, both plants removed 80% of the formaldehyde in 4 hours. The majority of this toxic removal was done by microorganisms in the roots, which were 11 times more effective at night. So, if you’re looking for a houseplant to remove formaldehyde from the bedroom, you may consider them.
A broader study assessed 86 plants for formaldehyde removal. Ferns were the most efficient at removing the VOC, with the Asian royal fern greatly surpassing most of the other plants on the list. This adds a new question mark to original NASA list and I’m curious whether there are other plants that may even be far better at removing VOCs.
Plants are able to remove formaldehyde from the air by their natural process of metabolism. While most of the studies have yet to test the plants in an actual, live indoor environment, the results are quite impressive. The question now is, which of these air-purifying plants will you choose for your own home?