There’s been a good amount of talk lately about the idea that certain plants you welcome into your home could help purify the indoor air. Unfortunately, while the science behind the notion is completely sound, in practice it’s pretty unlikely to work.
At least, the plants in your house are unlikely to clean all your air on their own.
And that, my friends, is because (among other reasons) you’d need to own and tend around 1,000 of said plants in order to rely on them to completely purify the oxygen you breathe.
The science comes from a 1989 NASA study that found that ficus, daisies, mums, and other plants could pull all of the cancer-causing volatile organic compounds, like benzene and formaldehyde, from airtight environments like the ones in the space stations.
Their potential effect, though, never really lived up to the hype, says Dr. Michael Waring of Drexler University.
“The main issue with the NASA study – and other chamber studies of potted plants and VOCs – isn’t that the data are incorrect. Rather, the interpretation of the data and its application to indoor air cleaning are flawed.”
Also, it’s important to mention that chamber studies like the ones conducted by NASA are not simulating real-world environments, so the data doesn’t exactly translate. The buildings we work and live in are well-ventilated, have continuous indoor-outdoor air exchange, and are generally full of decent quality breathing air to begin with, reminds Warring.
“Chamber studies have shown weak removal of VOCs by potted plants, just not at high enough rates to clean indoor air effectively compared to air exchange.”
Chemicals, too, are more regulated and specific in an environment like a space station.
“…in a home or office, there are mixtures of many different chemicals at different concentrations, which change all the time depending on exchange with outdoor and objects in the home or office that emit these chemicals.”
Other studies have been done that examine the effects of potted plants on real-world environments, and they have been found to have positive effects. That said, Warring says they remain flawed.
“The field studies typically did not measure the air exchange rate – the frequency with which indoor air is replaced by outdoor air, because that parameter wasn’t measured, changes in VOC concentrations can’t be ascribed to any particular removal mechanism.”
Basically, we’ve never proven that it’s actually the plants that are responsible for improving the air.
As far as the numbers? Warring says that, in a 10×10 foot bedroom or an office with an 8-foot ceiling, you’d need around 1,000 plants to match the air-cleaning capacity of a standard ventilation system.
Here’s the thing: if you enjoy having houseplants, you definitely should keep some around. They are shown to have other benefits to both mood and productivity, and they’re certainly not going to harm the air quality.
If the air quality is your main concern, open a window or two, and let in as much sunlight as possible.
A little fresh air and sunlight never hurt anyone.