Do Houseplants Really Purify the Air? The Truth Between "Healing" and "Science"

Just having a houseplant in the corner of a room can significantly change the space's impression. Add the green of a monstera, pothos, or sansevieria to white walls, wooden furniture, and light by the window, and the room instantly becomes a "lived-in place." Recently, houseplants are often introduced not just as interior decor but with explanations like "purifying the air," "absorbing harmful substances," and "good for health when placed in the bedroom."

So, do houseplants really purify the air in our homes?

In conclusion, the answer is neither "completely ineffective" nor "a substitute for air purifiers." Plants do have the ability to absorb some pollutants. However, scientifically, it's quite challenging for a few houseplants to significantly improve indoor air quality in a typical home. The important point here is that "what happens in a laboratory" and "what happens in a regular home" are not the same.

The starting point of this houseplant myth is often said to be the air purification experiment with indoor plants published in 1989 as part of NASA-related research. This study suggested that plants might reduce volatile organic compounds like benzene, trichloroethylene, and formaldehyde in a sealed experimental environment. It was a very interesting study when considering whether plants could help maintain air quality in closed spaces like future space stations.

However, there is a major pitfall here.

The NASA study assumed a sealed space with extremely limited air exchange. On the other hand, our homes are not completely sealed containers. Even with windows closed, air gradually exchanges through door gaps, vents, small gaps in walls and building materials, exhaust fans, air conditioners, and ventilation systems. Cooking generates oil smoke and particles, and cleaning releases components from detergents and sprays into the air. Pollution sources like furniture, building materials, air fresheners, heating appliances, and exhaust gases from outside are not one-time occurrences but exist intermittently or continuously.

In other words, the air in our homes is entirely different from a static experimental box.

Considering this difference, a review study published in 2019 evaluated past plant experiments against actual building air exchange rates. The result suggested that to remove VOCs with plants to a level comparable to general ventilation and air exchange, it might require 10 to 1000 plants per square meter of floor space. This far exceeds the amount realistically placeable in a typical home. It's unlikely that placing a few small pots would significantly lower the concentration of chemical substances in indoor air.

Of course, this doesn't mean "plants do nothing." Plant leaves, roots, soil, and the microorganisms living there may absorb or decompose specific chemicals under the right conditions. Recently, systems like "plant biofilters" that use fans to pass air around roots or media have been researched. Such engineered systems might have potential as air purification technology in the future.

However, that's a different story from "placing a pothos by the window." Talking about air purification technology using plants and houseplants at home as the same thing leads to excessive expectations.

Reactions on social media are also divided on this point.

In Reddit's plant-related communities, there are calm comments like "The story that plants purify the air spread from an old NASA study, but in an actual room, too many plants are needed to make a big impact." One post pointed out that if you seriously want to change the air quality in a room, you need enough plants to fill almost the entire living space. Another user criticized that while NASA study explanations are repeatedly reused in infographics, the crucial premise of "sealed experimental conditions" is often omitted.

On the other hand, from those who love houseplants, there are many reactions like "Even if the air purification effect is limited, having plants in the room feels good," "Spaces with plants have a unique 'plantiness,'" and "Rather than the air being cleaner, the room feels more calming." This cannot be ignored scientifically. The benefits of plants cannot be measured solely by how much they remove chemical substances from the air.

In fact, some studies suggest that houseplants enhance psychological comfort and satisfaction with space. Seeing greenery can make a room feel more peaceful, slightly reduce stress, and increase attachment to the living space. Having plants in a room can create small habits like watering and pruning, adding rhythm to life. Placing plants in a remote work room can soften an otherwise sterile workspace. These values don't appear on an air purifier's performance chart but are quite significant in daily life.

The problem is promoting plants excessively as a health measure without distinguishing between "what they can do" and "what they cannot do."

For example, placing houseplants in a musty room won't solve the root cause if it's due to condensation, leaks, or poor ventilation. Overwatering or neglecting saucers can increase issues with humidity, mold, and microorganisms. In a room with chemical odors, if the cause is new furniture, paint, adhesives, air fresheners, or spray products, reducing the source should come first. If smoke and particles from cooking are the problem, using an exhaust fan is crucial. For particles like pollen, dust, pet hair, and smoke, an air purifier with a HEPA filter of the appropriate size is more practical.

The basics of improving indoor air are first to reduce pollution sources. Next, ventilate when outdoor air quality is not bad. Then, if necessary, use an air purifier or filter suitable for the room size. If VOCs and odors are a concern, a system that addresses gaseous components, like an activated carbon filter, is needed in addition to HEPA. However, no air purifier can completely remove all pollutants.

In this regard, it's better to think of houseplants as "supporting actors" rather than "main characters."

If you seriously want to improve the air in a room, before increasing plants, you should review ventilation, cleaning, humidity control, source management, and filter performance. Especially in rooms with too high humidity, increasing the number of plants can be counterproductive. The management of plants themselves, such as watering frequency, pot ventilation, soil condition, and not leaving water in saucers, also becomes part of the indoor environment.

So, is there no point in having houseplants? Not at all.

In fact, by not overestimating their air purification effect, the true charm of houseplants becomes apparent. Plants are not substitutes for air purifiers but entities that enhance the quality of life. The color and shape of leaves add depth to a room, allow you to feel the change of seasons, and bring your home a little closer to nature. When you come home tired, just seeing the leaves by the window catching the light can relax you. When new shoots appear, there's a small sense of achievement. Such effects are hard to quantify but are valuable to those living with them.

The reaction seen on social media, "It's questionable if the air gets cleaner, but having plants in the room feels good," is, in a sense, the most realistic. Science does not deny plants. What it denies is the oversimplified promotional phrase, "Place a few pots, and air problems are solved."

Houseplants are placed because you like them. They are grown because they make the room comfortable. They are increased because the greenery is calming. That's enough.

If you're truly worried about air pollution, it's important not to rely too much on plants and to investigate the cause. For cooking smoke, use ventilation; for pollen and dust, clean and use filters; for chemical odors, review the sources; for mold, improve humidity and water areas. Plants can then be welcomed as entities that pleasantly arrange the space.

The most honest answer to the question, "Do houseplants purify the air?" would be this:

Houseplants can absorb some pollutants under the right conditions. However, they don't have the power to replace air purifiers or ventilation in a typical home. Still, they beautify the room, adjust the mood, and bring a small piece of nature back into your life.

In other words, houseplants are not "devices that save the air" but "companions that slightly improve life."

Source URL

Phys.org article "Can houseplants really purify the air in your home? What the science actually says"
Referencing the air purification effect of houseplants, NASA research, 2019 review, and explanations about ventilation and HEPA filters.
https://phys.org/news/2026-05-houseplants-purify-air-home-science.html

NASA Technical Reports Server "Interior Landscape Plants for Indoor Air Pollution Abatement"
1989 NASA-related study. Research investigating the potential of plants, roots, and soil microorganisms to reduce indoor pollutants in a sealed environment.
https://ntrs.nasa.gov/citations/19930073077

Journal of Exposure Science & Environmental Epidemiology / Nature "Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies"
2019 review study analyzing that it's unrealistic to significantly reduce indoor VOCs with potted plants alone when compared to actual building air exchange rates.
https://www.nature.com/articles/s41370-019-0175-9

PubMed "Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies"
PubMed listing information for the above review study. Used to confirm research summary and bibliographic information.
https://pubmed.ncbi.nlm.nih.gov/31695112/

EPA "Guide to Air Cleaners in the Home"
A guide by the U.S. Environmental Protection Agency on home air purifiers, HVAC filters, HEPA, limitations, and selection of air cleaners.
https://www.epa.gov/indoor-air-quality-iaq/guide-air-cleaners-home

Reddit r/botany "Can anyone help me understand plants and their ability to ‘clean air’ indoors/in a room"
Example of social media reaction regarding the air purification effect of houseplants, noting that a large number of plants would be needed in an actual room.
https://www.reddit.com/r/botany/comments/1i4bos2/can_anyone_help_me_understand_plants_and_their/

Reddit r/houseplants "NASA guide to air-filtering houseplants"
Example of social media reaction to the interpretation of NASA research and the suggestion that 10-1000 pots per square meter would be needed in typical buildings.
https://www.reddit.com/r/houseplants/comments/1k3rcp6/nasa_guide_to_airfiltering_houseplants/

Reddit r/houseplants "I know plants don't improve air quality, but do you feel like houseplants do give the air a....plantiness?"
Example of social media reaction evaluating the psychological and sensory comfort of spaces with plants, rather than air purification effects.
https://www.reddit.com/r/houseplants/comments/174p8m8/i_know_plants_dont_improve_air_quality_but_do_you/