Not in my House(plant)! The Myth of how Plants Improve Indoor Air Quality
If you’re concerned about how to improve indoor air quality, it’s likely that you’ve run across the idea that houseplants can help purify the air inside your home or office.
Sounds promising, and even probable…
Let’s see, page one from a Google search for “indoor air quality” AND “houseplants,” reveals the following titles:
- Air Purifying Plants: 9 Air-Cleaning Houseplants That Are Almost Impossible to Kill
- A breath of fresh air | 15 houseplants for improving indoor air quality
- 7 Plants That Can Actually Purify Your Indoor Air | Rodale’s Organic Life
- 12 Healthy Houseplants That Improve Indoor Air Quality – Dr. Mercola
- These are the best houseplants to improve indoor air quality, study finds*
- The Best Houseplants for Purifying Indoor Air (That Are Pretty Too!)
- Top 10 House Plants for Clean Indoor Air | The Healthy Home Economist
- Best Houseplants to Improve Indoor Air Quality | Today’s Homeowner
- 10 Houseplants That Improve Indoor Air Quality – Allergy & Air
- Top Houseplants for Improving Indoor Air Quality – Clean Air Gardening
Such a simple fix for your concerns about unhealthy indoor air! Just add one of the plants on any of these handy lists to your indoor space, and voila! Clean air!
Alas, Dear Reader! This simple fix will disappoint you; it holds a dark secret.
Let me explain…
In 1989, NASA published a study entitled, “Interior Landscape Plants for Indoor Air Pollution Abatement.” This study looked into the possibility for low-light plants to remove trace organic chemicals, specifically: Formaldehyde, Benzene, and Trichloroethylene—all substances known to be toxic to humans—from a closed/indoor environment. The results of the study found that, indeed, the plants were able to remove a percentage of these toxins from the air, and that “the plant root-soil zone appears to be the most effective area for removing volatile organic chemicals. Therefore, maximizing air exposure to the plant root-soil area should be considered when placing plants in buildings for best air filtration” (18). Another important component of this study is that it examined both the effect of plants on removal of trace chemicals, and the effect of using the plants in combination with an activated carbon air filter—the combined use of both the plants and the filter are where the authors of the study found the most improvement; in their summery, they state:
Low-light-requiring houseplants, along with activated carbon plant filters, have demonstrated the potential for improving indoor air quality by removing trace organic pollutants from the air in energy-efficient buildings. This plant system is one of the most promising means of alleviating the sick building syndrome associated with many new, energy efficient buildings. […] Activated carbon filters containing fans have the capacity for rapidly filtering large volumes of polluted air and should be considered an integral part of any plan using houseplants for solving indoor air pollution problems. (18)
In the subsequent years, these NASA scientists performed a few follow-up studies, which not only confirmed the air cleaning properties of these plants, but also provided a very useful rubric for easy implementation: for improved air quality, there must be at least one plant per 100 square feet of home or office space.
Great! Now we know that there are certain plants that can remove certain toxins from our air, and we only need one plant for every 100 square feet of indoor space!
[su_row][su_column size=”1/6″ center=”no” class=””][/su_column] [su_column size=”5/6″ center=”no” class=””]This is the bite-sized foundation upon which most current claims for the use of indoor plants to improve air quality are based. See here, and here, and here, and here, and on and on and on.[/su_column][/su_row]
Unfortunately, there’s a very important piece of information that is ignored by these modern retellings of NASA’s study. If you remember, the 1989 study concluded: “Activated carbon filters containing fans […] should be considered an integral part of any plan using houseplants for solving indoor air pollution problems,” which means that in order for these plants to aid in air quality improvement, they must be accompanied by a carbon filter! Moreover, these findings are only true within a closed chamber setting (like a spaceship—go figure!). Your cubicle on the ninth floor of the Civic Center Tower, unfortunately, is not a closed chamber, nor is your three-bedroom home with four full-sized doors that allow you to enter and exit from various directions. Way too many variables…
In 2016, Dr. Michael S. Waring, professor of Architectural Engineering at Drexel University, and director of the Indoor Environment Research Group, gave a conference presentation entitled: “Bio-walls and indoor houseplants: Facts and fictions,” wherein he explains all they reasons why this simple fix of purchasing a few Peace Lilies or Mother in Law’s Tongues are not tenable solutions to indoor air quality issues. Jumping over his scientific evidence—you can read his presentation here—and landing right at the juicy reveal: in his presentation, Dr. Waring concludes that, in order to improve the air quality of a working/living indoor space, you would actually need 100 plants per square foot—not one plant per 100 square feet!!
He does not completely discredit the possibility for houseplants to aid in air filtration, but he does say that a lot of work needs to be done before we can figure out how to actually receive that aid.
So for right now, yes: houseplants can be successful in removing the air toxins that are an inevitable by-product of our modern world, but only if our indoor air space is located in a jungle.
Just imagine it, you enter the Civic City Tower elevator, push “9,” and when the doors open: