Nanotechnology designed to cleanse the air of pollutants could be incorporated into our clothing, but – asks Martin Wright – are we ready to become walking cleaning agents?
Imagine you’re walking down a busy city street. And as you walk, the air around you becomes cleaner. Not because the mere sight of you stops people swearing. The air is literally being cleansed of pollutants, thanks to you. Or rather, your clothes.
Because your jeans, your top – any fabric you’re wearing – are coated in a certain nanoparticulate: titanium dioxide (TiO2) to be precise. This acts as a photocatalyst, using energy from sunlight to break down various pollutants, notably nitrogen oxides from car exhausts – a key constituent of today’s rising quantities of urban smog. The process converts NOx to nitric acid, which in turn reacts with calcium carbonate, locking the gases up in calcium nitrate, while also releasing (very small) quantities of CO2 and water.
It’s a well-established, proven process, increasingly used on a number of buildings [see 'Smart solutions for a material world'] and there are experiments underway to incorporate it in road surfaces too.
If it were applied to clothes, though, it would massively increase its pollution-cleaning impact. Studies have shown that the cleaning properties of TiO2 on buildings only extend to a range of around 25cm or so or so from the wall. People, on the other hand, could act as mobile cleansing agents, covering an area far larger than anything possible with a (static) building as they go about their business around town.
The aim is to allow us to ‘breathe more beautifully’
The idea of incorporating photocatalysts in clothes sprang from discussions between Professor Tony Ryan of the University of Sheffield, a specialist in polymer nanotechnology, and designer Helen Storey, currently Professor of Fashion and Science at the London School of Fashion. She designed the first ever ‘purifying dress’, displayed as an art installation entitled ‘Herself’, with the aim of allowing us “to breathe more beautifully”. Subsequently, she came up with a ‘Field of Jeans’ – a multitude of denims strung on lines.
Designing a pollution-eating dress is one thing; taking it to scale is another. You can’t realistically (or sustainably) expect people to invest in a whole new photocatalytic wardrobe! So Storey and Ryan approached Ecover, with a view to seeing if the chemical would work as a laundry additive. It had immediate resonance with the company’s high ecological standards, explains Tom Domen, international products manager. Research is now under way to see just how the TiO2 will perform in practice; in particular, how long it will last after being applied to clothes. At first, researchers considered simply adding it to detergent, but decided it wasn’t necessary to apply it in each washing cycle. So the focus now is on an additive, to be used in the regular wash every now and then.
Inevitably, there will be unease among some at the thought of adding anything ‘nano’ to their wash, although it wouldn’t be the first time that nanoscale TiO2 has been worn close to the skin. As Dolmen points out, it’s already present in a wide range of applications, notably suncream, toothpaste and bright white paint. (The line markings on Wimbledon tennis courts, for example, contain TiO2.) But to allay fears, Ecover is planning on having open discussions with NGOs such as Greenpeace, “to help assure people”, in Dolmen’s words, “that we’re not just replacing one pollutant with another”.
It’s early days yet, but Domen is confident that neither technology nor price will be a major obstacle. “The biggest challenge”, he says, “is how we persuade people that they want to have this. After all, we’re asking them to do something which, while completely harmless to them, won’t actually be bringing them any direct personal benefits. Rather, they will be a bringing a benefit to the community.”
Time will tell whether people will be prepared to pay for this – and if so, how much. It raises the tantalising question as to whether there’s a business model in altruism. But it would be nice to think that some people at least will be prepared to pay to help others “breathe more beautifully”. – Martin Wright
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Photo: iStockphoto / thinkstock