Catalytic clothing
October 4, 2011
Although the mighty steel production industry that once fed the northern English city of Sheffield buckled under the weight of cheap imports years ago, the air that fills its streets could still not be described as clean. But if local scientists get their way, that might be about to change, and Sheffield might acquire an altogether more innovative claim to fame.
Tony Ryan, the pro-vice chancellor for the faculty of science at the University of Sheffield, is convinced that the clothes we wear, could play an important role in cleaning the air.
He describes the garments as catalytic clothing – and the way they work is similar to a catalytic converter on a car. He proposes the use of titanium dioxide nano-particles, which can help break down air pollutants such as nitrogen oxide produced by cars.
This new design was demonstrated in London at an outdoor festival just last month.
"The key to how to do it is currently used in self-cleaning glass and self-cleaning architectural coatings," Ryan told Deutsche Welle. "They use titanium dioxide that's in such a form that when it sees sunlight and oxygen it makes bleach, it makes peroxide. And then the peroxide will react with pollution - it will take it out of the air."
Easy to use
Titanium dioxide can be sprayed onto or washed into clothes, and as a photo catalyst, it oxidizes pollutants in the air when light shines on it. Car fumes are broken down into largely harmless chemicals, which literally come out in the wash.
As Ryan points out, adding the nano-particles to detergents would only put the price up by some 0.10 euros ($0.13) per laundry cycle.
To achieve a noticeable effect on air quality, 30 people wearing catalytic clothing would have to walk past one meter of pavement every minute. That volume of pedestrian traffic, however, is not unusual in a busy city.
The root of the problem
But not everyone is jumping up and down at the prospect of Ryan's new rags. Simon Birkett of the non-profit organization Clean Air in London says off-setting pollution is not the solution.
"The long-term answer is tackling harmful emissions at their source," he said, and added that includes keeping the oldest diesel vehicles away.
"And you can fit what is called selective catalytic reduction equipment to vehicles which cleans up the harmful emissions at their source, rather than letting those pollutants get into the air, and then trying to clean them up afterwards through something like catalytic clothing or paint."
A genuine possibility?
Traffic in Sheffield pumps some 8,000 tons of nitrogen oxide into the atmosphere every year. To comply with incoming EU regulations the city needs to reduce that figure by 1,000 tons a year, which amounts to three tons a day.
Despite skepticism from some quarters, Tony Ryan says that with enough people on board, his catalytic clothing could help reach that goal.
"If half the population of Sheffield, which is half a million people, were wearing catalytic clothing they would be able to bring the level of nitrous oxide down to well below the legal limit," he said.
He believes that once people realize they have the power to do something about their air quality, they will put pressure on companies to provide the technology. He is already talking to detergent manufacturers who have expressed an interest in including the nano-particles in their future products.
Reporter: Lars Bevanger, Sheffield / tkw
Editor: Cyrus Farivar