Houseplants have a very limited ability to clean the air in your home. They can remove small amounts of pollutants from the air, but not enough to make a meaningful difference unless you have an realistic number of plants.
To test this out, we ran a hands-on experiment using real houseplants and sensors. Here is what we found.
Can Houseplants Clean Indoor Air?
Houseplants can absorb some pollutants, but the effect is very small. You would need hundreds of plants in a single room just to make small improvements to air quality. Houseplants are still useful for controlling humidity and for mental health benefits. Houseplants should not be used as a replacement for ventilation or air purifiers.
What Science Says About Houseplants and Air Quality
There are several research studies on the ability of plants to clean air indoors. The most popular study is the NASA Clean Air Study, which famously showed that plants can clean indoor air. However, the study was done in a highly designed laboratory setting, where a fan was used to pull air through an activated carbon filter. The plant roots would then absorb pollutants from the filter. This assessment is not a good reflection of plants true ability to clean air.
Other research studies that look specifically at the ability of plants to clean air show less promising results. In fact, a research study from 2019 analyzed 12 other studies containing a total of nearly 200 experiments on potted plants ability to remove VOCs. The study found that potted plants do not improve indoor air quality.
Our Experiment: Testing If Houseplants Can Clean Air
Research on the ability of plants to clean air in homes often comes from laboratory settings, rather than actual homes. The goal of our experiment was to determine if plants can clean air in a home based on data from a real home, rather than a laboratory or other setting.
Setup and Equipment
The experiment was pretty straightforward. We built a clear box out of clear acrylic sheets and put a houseplant in the box along with a custom built Arduino air quality sensor. To tightly seal off the box, we placed it on top of bubble wrap. As the weight of the boxes pressed down on the bubble wrap, the bubbles form a perfect seal by wrapping around the box.
Next, we put another Arduino air quality sensor in a separate box and sealed it off as well to have something to compare our results to. The box was left near a window in a bedroom that got sunlight for a portion of the day and general room lighting, as the room was used during the day. The goal was to mimic normal lighting behavior in a home.
Last, we started the sensors and programmed them to collect air samples every five minutes for five days. The sensors are capable of measuring the most common house pollutants, such as VOCs, and roll it into a single snapshot of air quality in parts per million (ppm).
In this experiment we also tried putting multiple plants in one box and using a grow light to see if that improved the results. We also visited a plant nursery to see what the air quality was like in a building that had hundreds of plants in it. If you want to build an air quality sensor yourself like we did, check out out tutorial on building an air quality sensor using an Arduino. If you prefer to buy one, we recommend the Airthings View Plus.
Experiments
- Experiment 1: One plant in a box compared to an empty box to gain a control measure
- Experiment 2: Two plants in a box compared to one plant
- Experiment 3: Adding a grow light to 2 plants
- Experiment 4: Visiting an indoor plant nursery
Setup and Equipment
Research on the ability of plants to clean air in homes often comes from laboratory settings, rather than actual homes. The goal of our experiment was to determine if plants can clean air in a home based on data from a real home, rather than a laboratory or other setting.
Results - What Happened to Air Quality
- Experiment 1: An improvement of about 20 ppm
- Experiment 2: An improvement of about 40 ppm
- Experiment 3: An improvement of about 60 ppm
- Experiment 4: An improvement of about 150 ppm
Experiment 1: One Plant
With one plant in the sealed box, the air quality improved by about 20 ppm compared to the empty box. This is a very small amount.
Experiment 2: Two Plants
With two plants in the sealed box, the air quality improved by about 40 ppm compared to the empty box. This is also a fairly small amount. However, considering the air quality improved by twice as much with twice as many plants, this gave some indication the experiment was working as anticipated and that more plants means cleaner air, even if minimal.
Experiment 3: Two Plants with A Grow Light
With two plants in the sealed box and a grow light, air quality improved by about 60 ppm, which is where our data suggests air quality could improve to if we had used a third plant instead of the grow light.
Experiment 4: Visiting An Indoor Plant Nursery
The air quality in the plant nursery was 150 ppm better than the control box. The plant nursery has hundreds, maybe even thousands of plants in it. Remember, our experiment was in a small sealed off box and the plant nursery is a very large indoor space. To improve the air quality by a similar amount, we would need to fit about 5-8 plants inside the box, depending on if the grow light was used.
So… How Many Plants Would You Actually Need?
To improve air quality in a home by just 20 ppm using plants, we estimated that you would need about 533 plants in a room that is 10 feet wide by 10 long tall. That is an unrealistic number of plants required to make a small improvement to air quality. As a reference, the EPA recommends keeping CO2 levels no more than 700 ppm above outdoor concentrations.
What The Results Mean for a Real Home
The results show that plants have a very limited ability to clean air in homes. Instead, you should depend on air purifiers, ventilation systems, or simply opening windows. One study found that opening windows can reduce CO2 exposure by over 80%.
FAQs About Houseplants and Air Quality
Can plants replace an air purifier?
No, plants should not be used to replace an air purifier.
Do plants remove VOCs like formaldehyde?
Yes, plants can remove VOCs such as formaldehyde, but only in small quantities.
Are houseplants still good for your home?
Yes! Plants may have a limited ability to clean air but they are great for decorating and adding a touch of nature to our indoor spaces.
Does having more light make plants clean more air?
Yes, based on our experiment adding more light in the form of a grow light increased the amount of air cleaned by the plants.
Limitations of This Experiment
This was a very small scale study done on just a single home and with a single type of plant. The air quality monitor was also made by our team, so it’s possible a more calibrated and professionally made air quality monitor would show different results. More experiments like this one should be conducted to confirm our results, including to fill a real room with hundreds of plants to confirm if the results are sound.
Final Verdict — Are Houseplants Worth It for Air Quality?
Houseplants are likely not worth the investment or care strictly for the purpose of improving air quality. You would need to house thousands of plants in every room of your house to make meaningful improvements to air quality. Instead add plants to your home because you enjoy them and use more dependable air quality improvement strategies like opening windows and air purifier systems.
