Common Houseplants Can Improve Indoor Air Quality

Ordinary potted houseplants can make a significant contribution to reducing air pollution in homes and offices, according to new research led by the University of Birmingham and in collaboration with the Royal Horticultural Society (RHS).

During a series of experiments monitoring common houseplants exposed to nitrogen dioxide (NOtwo) — a common pollutant — the researchers calculated that under some conditions, plants could reduce NOtwo up to 20 percent.

The researchers tested three houseplants that are commonly found in UK homes, easy to maintain and not too expensive to buy. They included peace lily (Spathiphyllum wallisii), Corn plant (fragrant Dracaena) and fern ring (Zamioculcas zamiifolia).

Each plant was placed, on its own, in a test chamber containing levels of NOtwo comparable to an office located next to a busy street.

Over a one-hour period, the team calculated that all plants, regardless of species, were able to remove about half of the NOtwo in the chamber. The performance of the plants did not depend on the environment of the plants, for example, whether it was in light or dark conditions, and whether the soil was wet or dry.

Lead researcher Dr Christian Pfrang said: “The plants we chose were all very different from each other, but they all showed surprisingly similar abilities to remove NOtwo of the atmosphere. This is very different from the way houseplants absorb COtwo in our previous work, which is highly dependent on environmental factors such as night or day, or soil water content.”

The team also calculated what these results might mean for a small office (15 m3) and a medium-sized office (100 m3) with different levels of ventilation. In a small, stuffy office with high levels of air pollution, they calculated that five houseplants would reduce NOtwolevels at about 20 percent. In the larger space, the effect would be smaller: 3.5 percent, although this effect would increase with the addition of more plants.

While the effects of plants in reducing NOtwo are clear, the precise mechanism by which they do so remains a mystery. Dr Pfrang added: “We don’t think the plants are using the same process they use for COtwo absorption, in which gas is absorbed through stomata (tiny holes) in the leaves. There was no indication, even during longer experiments, that our plants released the NOtwo it goes back into the atmosphere, so there’s probably a biological process going on that also involves the soil the plant is growing in, but we don’t know what that is yet.”

Dr Tijana Blanusa, RHS Senior Horticultural Scientist and one of the researchers involved in the study, said: “This complements RHS’s efforts to understand the scientific details behind what we know to be a popular passion. Understanding the limits of what we can expect from plants helps us plan and advise on plant combinations that not only look good but also provide an important environmental service.”

In the next phase of the research, the team will devise sophisticated tools for modeling indoor air quality that encompass a much broader range of variables. The new project, funded by the Met Office, will use mobile air quality measurement instruments to identify pollutants and test their effects in both residential and office spaces, producing a wealth of data to inform the development of the tool.

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Materials provided by university of birmingham. Note: content can be edited for style and length.

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