Indoor plants and green walls can reduce certain indoor air pollutants by roughly 10 to 30%, according to a review led by the University of Surrey and published on October 29, 2026 in the journal Eco-Environment and Health. Prof. Prashant Kumar, founding director of Surrey’s Global Centre for Clean Air Research, led the work, which drew on 35 international experts.
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The range comes with conditions attached. It applies to some pollutants and some systems, and the authors themselves list evidence gaps beside the benefits.
Cooling savings of up to 27 percent in some office zones
The summary of the paper on News-Medical reports the 10 to 30 percent pollutant reduction alongside several other findings. Some indoor greening systems could cut the energy needed to cool certain office zones by up to 27 percent, and the presence of plants was associated with temperature reductions of about 0.5 to 4.5 degrees Celsius around them. Passive greening, such as potted plants and living walls, can help remove volatile organic compounds released by products like paints and cleaning supplies.
Systems that actively pull air through plants and their growing media were often more effective under controlled conditions than passive ones. That distinction matters for anyone picturing a single fern on a desk: the strongest effects belong to engineered arrangements, and effectiveness in every case depends on ventilation, lighting, plant species and system type. The review’s pollutant range is a spread across those variables, not a promise for a given room.
The paper itself is hosted on ScienceDirect, and the News-Medical page credits the work to the UKRI-funded GREENIN Micro Network Plus, grant UKRI1239, which Kumar leads.
The cooling number deserves its own caveat. The 27 percent saving refers to office cooling energy in certain zones and cannot be carried over to a home, where occupancy, glazing and air conditioning habits differ. The temperature effect of 0.5 to 4.5 degrees Celsius is likewise measured close to the plants, so it describes a pocket of cooler air near the foliage and not the whole room. Both figures come from a pooled body of studies, which is why the review treats them as a benchmark and not a forecast.
Small test chambers versus occupied offices
Kumar framed the review as a preliminary benchmark for making informed decisions about where and how indoor plants can be most effective, and the wording is deliberate. Many of the studies it gathered used small test chambers and short monitoring periods, which may not reflect real-world or long-term performance in an occupied building.
Two GCARE researchers, Dr Elisa Valentim Goulart and Dr Hao Sun, said the review exposes a substantial gap in the monitoring and modelling of indoor greening impacts and that more research is needed. To close it, the authors propose a conceptual framework that combines monitoring with numerical modelling so that performance can be assessed under different conditions and used to guide building design, management and policy.
The review also names a risk that cuts against the benefits. As climate change pushes more extreme heat and humidity, poorly managed moisture around indoor greenery could raise the risk of condensation or mould, so how outdoor conditions affect indoor plant systems is flagged as an open research question.
Surrey’s GREENICON project and the EPA’s caution
The research network behind the review is not new to this territory. Surrey’s GREENICON project, also led by Kumar, studies how urban greening shapes indoor environmental quality, thermal comfort and health, treating outdoor and indoor conditions as a connected system. Air Quality News covered related work from the same network, which compared 26 indoor greening systems and quoted Kumar noting that people spend around 90 percent of their lives indoors. It gave no percentage figures, said larger engineered systems can make a space feel up to 2 degrees Celsius cooler without changing air temperature, and quoted Dr Tijana Blanusa of the Royal Horticultural Society welcoming the evidence on the conditions needed for benefits.
The U.S. Environmental Protection Agency takes a harder line on the ordinary houseplant. Its guidance on improving indoor air quality says there is currently no evidence that a reasonable number of houseplants remove significant quantities of pollutants in homes or offices. The agency calls controlling the source of pollution the most effective fix for most home air problems and treats ventilation as a useful supplement, and it warns against overwatering because soggy soil can encourage microbes that bother allergic people.
The two positions are less opposed than they look. Surrey’s 10 to 30 percent applies to specific pollutants under specific conditions, often in controlled settings or with engineered systems, while the EPA addresses the number of plants a household is likely to own. Neither source claims that a shelf of pots can replace opening a window or removing the paint, solvent or cleaner that releases the compounds.
What remains unsettled is the range itself. The version of the review that could be read overnight does not name which pollutants fall at the 10 percent end and which at the 30 percent end, and the full paper behind the ScienceDirect link was not available to confirm it.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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