Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies

Abstract

Potted plants have demonstrated abilities to remove airborne volatile organic compounds (VOC) in small, sealed chambers over timescales of many hours or days. Claims have subsequently been made suggesting that potted plants may reduce indoor VOC concentrations. These potted plant chamber studies reported outcomes using various metrics, often not directly applicable to contextualizing plants' impacts on indoor VOC loads. To assess potential impacts, 12 published studies of chamber experiments were reviewed, and 196 experimental results were translated into clean air delivery rates (CADR, m 3 /h), which is an air cleaner metric that can be normalized by volume to parameterize first-order loss indoors. The distribution of single-plant CADR spanned orders of magnitude, with a median of 0.023 m 3 /h, necessitating the placement of 10-1000 plants/m 2 of a building's floor space for the combined VOC-removing ability by potted plants to achieve the same removal rate that outdoor-to-indoor air exchange already provides in typical buildings (~1 h −1). 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.

Using Ambient Scent to Enhance Well-Being in the Multisensory Built Environment

“…Over the years, there have been a number of reports suggesting that indoor plants might provide an effective means of helping to absorb the VOCs (Wolkoff et al, 2006) that tend to build up indoors (e.g., Brown et al, 1994;Guieysse et al, 2008), as well as possibly providing a range of other psychological benefits to the occupants of office buildings (Bringslimark et al, 2009;Nieuwenhuis et al, 2014). However, the latest research suggests that the number of plants that would be needed to exert a significant effect on VOCs is realistically too large for all but the Amazon HQs of this world to achieve (Walker, 2000;Cummings and Waring, 2020). Amazon HQ, known as The Spheres, and situated in downtown Seattle, consists of a biome of three huge plantfilled domes (Hartmans, 2018), housing an estimated 40,000 plants, encompassing more than 400 different species (see also Everett, 2019).…”

Adaptation of Indoor Health and Comfort Criteria to Mitigate Covid-19 Transmission in the Workplace

“…Routine rapid and swab testing Green wall integrated with the architecture will have a beneficial impact on the quality of indoor space and improve the indoor health index (Kazemi, Rabbani, & Jozay, 2020). The use of potted plants start to affect on indoor air quality when one plant is used per m 2 (Cummings & Waring, 2020).…”

The evolution of botanical biofilters: Developing practical phytoremediation of air pollution for the built environment

“…Although the VOC-sealed chamber experiments have clearly shown potted-plants are capable of VOC degradation, it is likely that they have limited practical value, as the large volume of spaces within the built environment relative to the size of even the largest potted-plants and the persistent emission of VOCs reduces the capacity of potted-plants to provide clean air [39]. Furthermore, it is unclear how such systems would perform with complex mixtures of VOCs in concentrations much lower than those commonly used sealed chamber experiments, as is the normal situation in situ.…”

“…In sufficient light, plants photosynthesize and thus have the potential to provide CO2 reductions to the indoor environment. The capacity of potted-plants to provide CO2 reductions has been demonstrated in several sealed-chamber experiments [59][60][61], however, as for VOCs, it is likely that findings from laboratory sealed-chamber pull down experiments will not apply to real-world situations [39,40]. For example, Torpy et al [62] estimated that 249 potted-plants would be needed to completely remove the respired CO2 from a single occupant in an unventilated, average sized room.…”