You can find articles all over the web declaring that certain plants like the Snake Plant, Spider Plant and others can clean the air in your home and/or increase the level of oxygen. These articles often cite a NASA study that proved it scientifically. Therefore, they say, you should buy these pants for the health of your family. Should you really buy houseplants to improve the air quality in your home? This is mostly untrue. Some even list plants that are “approved” by NASA for improving air quality. NASA doesn’t approve houseplants.
What Did NASA Find?
NASA did, in fact, do a study on the ability of common houseplants to remove specific toxins from the air. Specifically, they studied the ability of plants to remove ammonia, benzene, formaldehyde, xylene, and a couple other volatile chemicals that are known carcinogens. The lead author, B.C. Wolverton, conducted the experiment (1) in a small, air-tight sealed room. They found that in this environment, these toxins were reduced over time mainly by the action of the plants’ roots, soil, and the microbes living in the soil associated with plant roots. Adding a charcoal filter and a fan to draw the air into and through the soil improves this effect markedly.
Does it Work in the Home?
In a typical, non-hermetically sealed home, the air is in constant circulation, not only from room to room, but from outdoors to indoors. To make a long story short, the air is replaced in the home so often that no meaningful houseplant air cleaning can take place. In fact, to achieve the same amount of air cleaning that is achieved by natural air circulation in the home, a study (2) by B.E. Cummings and M.S. Waring found that up to a thousand plants per square meter of floor space would be required. Unless you’re prepared to add 90,000 pants to a 1000 square foot home, don’t think houseplants are going to make your air quality problems better.
The Real Benefit of Houseplants
Houseplants and natural greenery do offer some benefits to overall health. Linjing Deng and others found (3) that “Indoor plants have also been shown to have indirect unconscious psychological effect on task performance, health, and levels of stress.” The reduction of stress by providing a more natural, friendly environment is an important benefit of having houseplants in the home or work environment.
In short, houseplants don’t appreciably change the air chemistry in the typical home, but for many people they do decrease stress and improve one’s mental and emotional outlook. If houseplants make you happy, buy them. If you want better air quality in your home, open a window or buy an air purifier with filters that include a layer of charcoal to remove the smallest volatile chemical particles.
1) Wolverton, B. C. (NASA John C. Stennis Space Center Bay Saint Louis, MS, United States) Johnson, Anne (NASA John C. Stennis Space Center Bay Saint Louis, MS, United States) Bounds, Keith (Sverdrup Technology, Inc. Bay Saint Louis, MS., United States) Technical Memorandum, Publication Date: September 15, 1989. Interior Landscape Plants for Indoor Air Pollution Abatement - NASA Technical Reports Server (NTRS)
2) Cummings, B.E., Waring, M.S. Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies. J Expo Sci Environ Epidemiol 30, 253–261 (2020). Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies | Journal of Exposure Science & Environmental Epidemiology (nature.com)
3) Deng L, Deng Q. The basic roles of indoor plants in human health and comfort. Environ Sci Pollut Res Int. 2018 Dec;25(36):36087-36101. doi: 10.1007/s11356-018-3554-1. Epub 2018 Nov 1. PMID: 30387059. The basic roles of indoor plants in human health and comfort - PubMed (nih.gov)