# Drexel review: potted plants would need 10–1000 per m² to match ventilation in removing VOCs

- Published: 2026-11-08 06:08 UTC
- Section: Planet › Ecology & recycling
- Tags: potted plants VOC removal, indoor air quality, clean air delivery rate, Drexel University review, air exchange rate, NASA 1989 plant study, biofiltration, volatile organic compounds
- URL: https://realtech.media/news/rt-8ce21fa7102c92e4fd798305_drexel_review_potted/

**Drexel University researchers converted 196 chamber results from 12 studies into air cleaner units. The median for a single potted plant was 0.023 m³/h of VOC removal.**

![Drexel review: potted plants would need 10–1000 per m² to match ventilation in removing VOCs](https://realtech.media/media/2026/11/951459b9f2bef272.jpg)
*catracalivre.com.br*

Researchers at Drexel University in the United States reviewed 12 published chamber studies of potted plants and concluded that the plants remove volatile organic compounds (VOCs) too slowly to matter in a typical building. The paper appeared in the Journal of Exposure Science & Environmental Epidemiology [1]. The team, Professor Michael Waring and doctoral student Bryan Cummings, translated 196 experimental results into a common metric. To match the removal rate that outdoor-to-indoor air exchange already provides, 10 to 1000 plants per square metre of floor would be needed [1].

## How the chamber data were compared

The original experiments were run in small sealed chambers over many hours or days. Their outcomes were reported in various metrics that do not directly show what plants do to VOC loads in a room [1]. The authors converted each result into a clean air delivery rate (CADR, m³/h), the metric used for air cleaners, which can be normalised by volume to describe first-order loss indoors [1].

The distribution of single-plant CADR spanned orders of magnitude, with a median of 0.023 m³/h [1]. The authors compared it with the air exchange of typical buildings, about 1 h⁻¹ [1]. In a 50 m² apartment, even the most optimistic case of 10 plants per m² would call for 500 pots.

The idea of plants as air purifiers goes back to a 1989 NASA study on cleaning air in space stations, which reported that some species removed benzene and formaldehyde. Those tests were also done in sealed chambers, unlike a living room with doors, gaps and people moving through it.

## What the authors propose next

VOCs are released by paints, varnishes, particleboard furniture, cleaning products and cosmetics. In the reviewed studies, ventilation diluted pollutants much faster than leaves absorbed them. Waring said that plants do not clean indoor air fast enough to have an effect.

The authors suggest that future experiments move away from plants' ability to passively clean air. Instead, they name several directions: VOC uptake mechanisms, alternative biofiltration technologies, the productivity and well-being benefits of plants, and the negative effects of other plant-sourced emissions. These questions, they write, must be assessed by rigorous field work that accounts for important indoor processes [1].

## Sources

1. [Journal of Exposure Science & Environmental Epidemiology](https://doi.org/10.1038/s41370-019-0175-9)
2. [catracalivre.com.br](https://catracalivre.com.br/noticias/nao-e-a-planta-que-limpa-o-ar-da-casa-revisao-de-30-anos-de-estudos-calculou-que-seriam-precisos-de-10-a-mil-vasos-por-metro-quadrado-para-igualar-uma-janela-aberta)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-8ce21fa7102c92e4fd798305_drexel_review_potted/