I regularly see healthy-living experts touting the use of houseplants to clean indoor air. Unfortunately, most research does not support this claim. I have a lot of plants in my home because I appreciate their aesthetic value. I hope that they contribute some small benefit to my home’s air quality but I don’t rely on them to do the job. Let’s look at the facts to see if there are benefits and perhaps even risks to filling your home with potted plants.
The idea that plants are effective at removing VOCs from indoor air stems from a 1989 NASA study that tested different types of houseplants in a sealed chamber. The testing methodology was designed to simulate the small, air-tight environment of a space capsule. The study found that under these conditions, some plant types were particularly effective at removing VOCs including formaldehyde and benzene.
Subsequent studies have shown that the results do not translate to a typical house. The size of a house and the amount of ventilation play a big role in the how much impact a plant will have on air quality. A 1991 EPA review of the NASA study determined that a typical house would require 680 plants to yield the same results. A 2019 review of 30 years of research determined that it would take 10 to 1000 plants per square meter of floor space to provide more effective cleaning power than opening a couple of windows.
If you do choose to have houseplants in your home make sure you are not adding VOC pollution.
- Use untreated metal, clay or ceramic pots.
One study found that 11 different volatile organic chemicals (VOCs) were emitted into the air from plastic pots.
- Buy organic plants, grown without pesticides.
Pesticides used in the plant production process can have volatile emissions.
- Make sure your plants are not a source of mold.
Regularly check the soil for signs of mold.
If you see a recommendation to use houseplants to clean your air make sure you understand the source behind the recommendation and determine if this is new data that factors in a typical home environment or if it is simply advice based on outdated research.