House Plants - Do They Help Indoor Air Quality?

Live plants inside your home can provide a sense of unity with nature. Many people also believe that their house plants will clean their home of air pollution. But will they?

article continues below ↓

Actually, some early studies by the National Aeronautics and Space Administration (NASA) did indicate that some living plants could provide reduced formaldehyde levels. In their initial research, NASA scientists placed plants inside a sealed chamber, injected a certain amount of formaldehyde into the chamber, then measured the concentration of formaldehyde after a certain amount of time had passed. After a while, the formaldehyde had, in fact, disappeared. What appeared to have happened was the plants metabolized the formaldehyde and used it as food. Later, it was determined that it was actually bacteria on the plant’s roots that did the formaldehyde metabolizing, not the plant’s themselves.

NASA’s early findings have since been challenged. More-thorough research at Ball State University, and at other laboratories, has concluded that house plants (or the root bacteria) simply can’t substantially reduce formaldehyde or other contaminant levels found in indoor air. (Note: Plants can reduce carbon dioxide (CO2) levels, but CO2 is not considered an air contaminant.) In these more recent tests, plants were again placed in sealed chambers, but with a continuously outgassing source of formaldehyde, such as particleboard. (Houses often contain particleboard and other continuously outgassing sources of formaldehyde, so these new experiments were designed to mimic a real-world situation.) The results were disappointing. There was only a slight lowering of formaldehyde levels—no really significant reductions. So, in a real-world situation, where there’s a continuously outgassing source of formaldehyde, plants (or their accompanying bacteria) can slowly metabolize some of it, but not as quickly as additional formaldehyde released.

Interestingly, if you have very many plants in your home, this can lead to a higher indoor relative humidity (from the ongoing watering), and formaldehyde outgasses at a faster rate as the air’s moisture content goes up. So, you may actually increase formaldehyde levels inadvertently. In the end, it must be concluded that, while house plants will create a certain amount of oxygen, they simply aren’t effective air filters in this context.

Even though they aren’t going to substantially improve the air in your home, you’ll probably still like to have a few live house plants around. If so, you might consider choosing either cacti or succulents (plants with thick waxy leaves). Cacti and succulents require only occasional watering and misting, and little in the line of routine maintenance. Without the need for a great deal of water, these plants rarely become contaminated with mold or mildew—a real plus for mold-allergic people. Having lower water requirements also tends to lessen the chances of insect infestations and plant diseases. Finally, fertilizer applications with cacti and succulents are usually kept to a minimum.

(Note: The views expressed in this article are those of the author, and do not necessarily represent those of The Healthy House Institute, LLC.)

HHI Error Correction Policy

HHI is committed to accuracy of content and correcting information that is incomplete or inaccurate. With our broad scope of coverage of healthful indoor environments, and desire to rapidly publish info to benefit the community, mistakes are inevitable. HHI has established an error correction policy to welcome corrections or enhancements to our information. Please help us improve the quality of our content by contacting allen@healthyhouseinstitute.com with corrections or suggestions for improvement. Each contact will receive a respectful reply.