The Impact of Indoor Plants on Air Quality and Well-Being
What the Research Actually Says About Plants and Air Quality
Aside from being pretty to look at or offering you moral support at the office, the benefits of houseplants have been said to range from air purification to enhancing physical recovery. But how much of that is true? If plants do improve air quality, how effective are they? And what other health benefits do they provide?
The idea that indoor plants improve air quality largely stems from a 1989 NASA study that’s still widely cited today. In the study, a NASA scientist named Bill Wolverton enclosed different houseplants in plexiglass chambers and pumped the chambers with benzene, formaldehyde, and trichloroethylene, all common indoor air pollutants. After a 24-hour period, Wolverton found that the presence of the pollutants was significantly reduced, leading him to conclude that houseplants do improve indoor air quality.
Many other studies following the NASA study continued to find that plants absorb different common indoor air pollutants. However, common critiques of these studies is that many of them took place in laboratory conditions which vary significantly from real-life house or office environments, and that the plants in the study conditions were oftentimes enclosed in small spaces in order to control and measure the amount of pollutants in the air. You’d need to scale up the amount of houseplants with the space they’re in to get the same results from laboratory studies at a larger scale. One critique of the NASA study estimated that you’d need 680 houseplants in a typical house in order to get the benefits of houseplants that the NASA study claimed were possible.
So, do plants improve air quality? The answer is more nuanced than a simple yes or no. While studies indicate that houseplants do absorb common household pollutants, the effects of plant purification are probably overestimated, because the studies were conducted in laboratory settings instead of measuring the air purifying effects of houseplants in home or office spaces.
In one laboratory setting, the plants that were found to be the best air-purifying plants for all indoor air pollutants were hemigraphis alternata, hedera helix, hoya carnosa, and asparagus densiflorus. That being said, there has not been enough research done on the air purifying powers of these houseplants in home or office environments to be able to make the claim that they significantly impact air pollutant levels in your home. In real-life spaces, even the best air-purifying plants are most effective when used alongside an HVAC or filtration system.
However, as showcased by these studies, the more plants you have in a room, the more significant the air purification benefits become. That’s why we recommend Biome’s green walls, which are largely self-sustaining walls of living plants. Biome walls drastically increase focused ventilation of air through the plants and plant nutrition, meaning much more air passes through Biome’s plants and mineral nutrition than standard houseplants, yielding a significant amount of air that is plant-filtered. Biome walls also use a particular combination of minerals instead of soil. This enables for both better filtration and more natural air, as the porous minerals filter air effectively and host a specific microbiome that interacts with the air in a naturalizing way. These changes along with the pure quantity of plants cause the impact of the green wall to be closer to that of a micro-forest than a houseplant.
Health Benefits of Houseplants Beyond Air Purification
The benefits of houseplants reach beyond air purification. Research continues to show that houseplants have a positive effect on peoples’ overall well-being. A 2022 meta-analysis on the effects of indoor plants on human health, which looked at studies in both English and Chinese over a 50-year time frame, concluded that indoor plants have a positive effect on participants’ functions. In particular, houseplants have a calming effect and were shown to enhance cognitive functions.
It’s perhaps easiest to observe the health benefits of houseplants when you look at studies wherein the participants are recovering hospital patients. A 2023 study on the impact of indoor plants on patient recovery concluded that houseplants contributed to patients’ relaxation and improved their coping mechanisms during recovery.
The benefits of houseplants aren’t just physical. A 2023 review which looked at epidemiological studies on indoor plants and mental health concluded that, while evidence on this topic is limited, the studies that fit this criteria showed that houseplants improve mental health in a variety of environments from home to office.
On a larger scale, it’s clear that spending time outdoors among plants in their natural element is beneficial. One example of this can be found in the Japanese practice of Shinrin-yoku, or “forest bathing”. Shinrin-yoku isn’t running, hiking, or any other kind of exercise, but simply spending time in the forest, undistracted, using all five senses to absorb the experience of nature. Studies on the effects of Shinrin-yoku observe many benefits, such as reduced blood pressure and heart rate, reduction of stress hormones, reduced anxiety, depression, anger, fatigue, and confusion, and improved sleep quality, among other benefits. With this in mind, if you need a reason to buy another plant, it follows that the benefits of houseplants will likely mirror the benefits of spending time outdoors, so the more, the merrier.
Though these studies don’t necessarily tell us why or how the presence of plants has a calming effect, the research is pretty conclusive that the benefits of houseplants are numerous, and that exposure to nature does benefit our physical and mental health. At the end of the day, while the air purification effects of houseplants are probably overestimated, they certainly don’t harm you and might be marginally useful when used alongside another air filtration system. However, it’s more accurate to say houseplants benefit your well-being—from mental health to cognitive function—than to rely on them as primary air purifiers.