In 1989 NASA published the results of a major research study on the relationship between plants and air quality. For astronauts travelling beyond the stratosphere in sealed containers, finding a means of effective air-purification was a necessary as building an engine that would take them there. The study, headed by acclaimed scientist Bill Wolverton, found overwhelming support for the idea that plants expel clean air and remove VCOs (volatile organic chemicals are cancerous compounds produced by solvents, industrial processes, road vehicles and other nasties).
Wolverton’s research even gestured towards the kinds of plant that are most effective when it comes to air-purification, his personal favourite being members of the pothos family - which you can buy for yourself here and here.
The processes that enable plants to photosynthesise contribute to their ability to absorb harmful pollutants and gasses. We know that plants need water, sunlight and nutrients, but they also need particular atmospheric properties to survive. To absorb carbon dioxide, plants have tiny pores on their foliage which allow them to take in and expel gasses, like breathing (this is why it’s so important to dust your plant’s leaves and to prevent build up). As your green friend absorbs the carbon dioxide he needs to survive, he also mops up some of the invisible nasties infiltrating the air.
Wolverton himself continues to propound the benefits of plants to household environments in his subsequent (peer-reviewed) books, in research papers and at a conference held in Washington in conjunction with the US congress' Plants For Clean Air Day. But his work has come under criticism of late.Time magazine published an online article questioning the extent to which Wolverton’s study would apply to real-world environments, and The Atlantic and online publication Live Science followed suit with copycat pieces. The piece, authored by Markham Heid, argued that the evidence base for the phenomenon was strongly dependent on the laboratory conditions in which scientific studies have been conducted.
Specifically, Heid posed that the results of NASA’s study would be far less significant in the home, where the air is changed frequently as we open doors and windows. But by this logic, NASA’s results would apply to those of us who live and work in high rise buildings, in offices with windows that don’t open, or in areas where noise and pollution make opening windows an impossibility. Additionally, when air is controlled artificially, with conditioning and ventilation systems, it becomes dry, which in turn irritates lungs, eyes and skin. Plants do not just redress the atmospheric qualities of our environment, but increase humidity; a welcome relief for those of us with respiratory problems such as asthma.
It's also likely that the negative correlation between indoor plants and levels of fatigue, blood pressure and post-operative pain is in part due to the interaction between plants and the environment.
It's fair to say that the jury is still out over just how effective plants are at purifying the air in our homes, but I think you can probably guess which side of the debate we're on! Just think about the difference between running around a park (even in central London) and running along a heaving thoroughfare. Whatever your conclusions are, many of the best air purifiers are also the best looking plants.
Below are some of our favourites:
All calatheas are efficient air-purifiers, removing everyday toxins from our homes. They are also pet safe and tolerant of shadier rooms, so it's a good tropical, calming, long-life plant. The leaves on the Dottie are a beautiful deep purple, with bright pink markings.
When asked which plant was his favourite air purifier, NASA researcher Bill Wolverton named the pothos family. This particular pothos is also one of our favourite hanging plants.
An Australian and New Zealand native, this delicate fern has shiny, wavy leaves. They never grow beyond about 1ft in height but can spread out 2-3ft in width! It likes medium to bright indirect light and as most ferns, is partial to humidity although this one does well without too.