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Do Houseplants *Really* Clean the Air? Here’s What Scientists Say

Air-purifying houseplants are a popular request, but do plants actually clean the air? Here's the surprising truth.

Written by
Erika Schwerdfeger

With many folks spending more time than ever at home this past year, it’s no wonder that indoor air quality has taken on greater importance for many of us.

While air purifiers can be wonderfully effective tools for filtering out the pollutants and particles that often pervade homes, they’re also very costly with many models retailing for hundreds of dollars. That's why it's not uncommon to opt for low-cost, air-purifying houseplants instead. But one question remains: Do they actually clean the air?

Do Plants Clean the Air? Sadly, No—Not Enough, Anyway

There are several common plant species that have been evaluated for their ability to reduce indoor air pollution, with NASA pioneering the study in 1989. While past studies showed promising results, there was only one issue: They were conducted in a sealed chamber in a lab, not in a typical home environment. A 2019 study in the Journal of Exposure Science & Environmental Epidemiology reviewed 30 years of studies and found plants don't purify the air as much as once thought.

According to Michael Waring, PhD, an associate professor of architectural and environmental engineering in Drexel University’s College of Engineering, it would take "between 100 and 1,000 plants per square meter of floor space to compete with the air cleaning capacity of a building’s air handling system, or even just a couple open windows in a house." To put that into perspective, a typical car parking space is said to be about 12 square meters.

"This has been a common misconception for some time," Waring said in a press release. "Plants are great, but they don’t actually clean indoor air quickly enough to have an effect on the air quality of your home or office environment."

Squeezing between 100 and 1,000 plants into that tiny of a space isn't even something our biggest plant-loving idols could manage. Houseplants that clean the air might not be a thing, but bringing greenery into your home does have some other benefits worth noting.

The Real Benefits of Houseplants

While plants aren't great at purifying the air in homes, there are plenty of benefits that do come from creating an indoor jungle. The main one being how they can improve your mental health.

According to Matthew Flanigan, MD, a doctor in Columbus, Ohio, maintaining houseplants can improve your mood and make you feel happier and more optimistic. They can also lower stress and anxiety, and improve mindfulness.

"Houseplants engage the senses, especially touch and smell," Dr. Flanigan told Ohio State University. "Being engaged in the moment can help prevent anxiety, depression, and insomnia. This can boost productivity and decrease cortisol levels."

That's not all. Dr. Flanigan says a home filled with houseplants also gives you a sense of purpose and responsibility, as you're caring for a living thing. In addition, you may get a brain boost—and who wouldn't want that? "Maintaining plants might stimulate your brain and increase your attention span," he says.

Air quality aside, there are plenty of reasons to head to your local greenhouse and stock up on some new houseplant friends. Who knows—you may even feel happier and more productive from having them around.