Do indoor plants really purify the air in your home? Here’s what the science says
Are those indoor plants you bought really going to purify the air? Maybe not.
Even though some garden centers advertise house plants as a way to “eliminate air pollutants,” some scientists say there isn’t enough evidence that it does that.
So why the confusion? Research for years suggested that houseplants cleansed the air of toxins.
It started with NASA scientist Bill Wolverton claiming that household plants could provide a “promising, economical solution to indoor air pollution” back in 1989. He studied if plants could remove volatile organic compounds (VOCs), which are found in various products in your home, from the environment and potentially deep-space stations.
More recent information contradicts that idea.
“While there are several studies that indicate some plants can remove or reduce levels of some chemicals indoors, there is currently no evidence that a reasonable number of plants indoors can effectively control indoor air pollution,” the Environmental Protection Agency told McClatchy News, noting the agency has not done a study on the issue.
Air quality is measured by levels of carbon monoxide, nitrogen oxide, ground-level ozone and particle pollution, according to the EPA.
Every time you buy a plant, it converts the carbon dioxide we exhale and helps eliminate gases from the atmosphere, researchers said.
But houseplants make “at best, modest contributions of about 0.9–9% to indoor ozone removal effectiveness,” according to research published in the journal Building and Environment in 2017.
Researchers conducted tests in laboratories to mimic the effects plants have in homes and found that they barely affected the environment. If anything, you’d have to deck out your entire home with plants to see a major difference, according to the study.
Another study published in 2020 in the Journal of Environmental Management found that plant species “can be used to create a horticulturally sustainable internal green wall, and also improve the health index in the building interior environments.”
But lining your home with plants from top to bottom isn’t always a good idea, the Environmental Protection Agency told McClatchy News.
“An increased number of plants indoors could, under certain conditions, increase indoor humidity to problem levels or promote the increased growth of microorganisms, including some which can affect allergic individuals,” the agency said.
When plants pull water from the soil to stay hydrated, some is used but in “many types of plants about 97% of the water evaporates from the leaves into the air,” the agency said.
“Moisture in air could increase humidity in the space to levels that might cause health and comfort impacts for occupants and lead to mold growth or other organisms,” the agency said.
Americans spend 90% of their time indoors where toxins can be up to five times higher than outside air, according to the agency.
Garden shops and plant blogs often list which species are best at removing airborne pollutants, but it’s unclear that buying that Boston Fern or English ivy would improve your health, researchers said.
A 2018 opinion paper published in Trends in Plant Science suggests that there isn’t a definitive answer as to which plants are the most effective.
“The capacity of plants to remove indoor air pollutants through stomatal uptake (absorption) and non-stomatal deposition (adsorption) remains largely unknown,” the paper said.
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