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Most people don’t realise just <\/b>how many pollutants, external<\/span><\/a> are swirling around indoors, where they typically spend most of their time. <\/b><\/p>\n For example, many of the products we use for cleaning and freshening our homes, schools and workplaces are adding invisible toxins to the air.<\/p>\n “The smell of fresh is not a smell,” says Anne Hicks, a paediatric pulmonary specialist at the University of Alberta.<\/p>\n “If you can smell it, there’s a chemical in the air that’s getting up your nose. So all of that is air pollution, whether it smells good or bad,” she says.<\/p>\n “Indoor air pollution is huge, and it’s a relatively unknown frontier, because even my next-door neighbour’s house has a different air pollution fingerprint than my house would have,” Dr Hicks says.<\/p>\n Indoor air pollution is highly complex, little regulated, and often beyond individual control. For instance, road traffic produces nitrogen dioxide, while moisture and structural issues in buildings can lead to mould.<\/p>\n Air purifiers with high efficiency particulate air (HEPA) filters can help. But the initial cost plus the energy to run them can be out of reach for some households.<\/p>\n This is one reason that it’s so appealing to think of potted plants as passively, and inexpensively, cleaning the air. Essentially, plant leaves take in carbon dioxide and other pollutants, which are then used in various plant processes or broken down.<\/p>\n Especially important here are the community of micro-organisms and the growing medium (such as soil or compost), which in many studies do more to absorb pollutants, external<\/span><\/a> than the plant itself. <\/p>\n An influential NASA study from 1989, external<\/span><\/a> found that indoor plants could remove formaldehyde and other volatile organic compounds (VOCs) from the air. But the study was unrealistic for real-world conditions.<\/p>\n