Air quality has become a major topic of study in recent years, with data revealing that terrible air quality — both indoor and outdoor — can lead to a variety of illnesses and even increased mortality. It’s tempting to imagine that bringing a bit of nature into your home in the form of a potted plant might move the needle in your favor, but a new study published in the Journal of Exposure Science & Environmental Epidemiology suggests that’s just not the case.

The study is a meta-review of a dozen other research efforts related to the study of indoor air quality and what factors directly affect it. The analysis focused on how well efficiently potted plants can remove volatile organic compounds (VOCs) from indoor air. Unfortunately, they’re pretty bad at it.

As the researchers explain, many studies have demonstrated the ability of potted plants to remove VOCs from the air in a controlled environment like a sealed box. The rates at which the plants clean the air were observed and reported in these past studies. In the new report, the scientists convert that data into what is called a clean air delivery rate, which is a more realistic metric that tells us how much clean air we can expect a plant to produce, and how many plants would be required to clean the air in a given space.

The report suggests that, on average, a minimum of ten plants would be required to ensure clean air in just a single square meter of floor space. To match the clean air delivery rates of common outdoor-to-indoor air exchange systems which are already common in most offices and larger buildings, as many as 1,000 plants per square meter would be needed.

The report concludes:

Future experiments should shift the focus from potted plants’ (in)abilities to passively clean indoor air, and instead investigate VOC uptake mechanisms, alternative biofiltration technologies, biophilic productivity and well-being benefits, or negative impacts of other plant-sourced emissions, which must be assessed by rigorous field work accounting for important indoor processes.

That’s not to say that keeping a plant at your desk won’t brighten your day a little, especially in the dark gray days of winter. Just don’t expect it to do much work.