Scientists discover method to eliminate shoe odour
Almost every household has at least one pair of shoes whose odour is impossible to ignore.
Multiply that by a family’s worth of footwear, stack them on a rack, and you have a domestic design problem that’s as pungent as it is universal.
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Two Indian researchers decided this wasn’t just about stink – it was about science.
They set out to study how foul-smelling shoes shape our experience of using a shoe rack, and in doing so, stepped into the hallowed – and hilarious – halls of the Ig Nobel Prize, a tongue-in-cheek award for silly but inventive scientific endeavour.
Vikash Kumar, 42, assistant professor of design at Shiv Nadar University outside Delhi, taught Sarthak Mittal, 29, during his undergraduate years. It was at the university that the two first hit upon the idea of studying smelly shoes.
So the two embarked on a survey in the university hostels, asking a truly human question: if our sneakers reek, doesn’t that ruin the entire experience of using a shoe rack?
Their survey of 149 university students – 80 per cent of them male – confirmed what most of us already know but rarely admit: more than half had felt embarrassed by their own shoes or someone else’s stink, nearly all kept their footwear in racks at home, and hardly anyone had heard of existing deodorising products.
Homegrown hacks – tea bags in shoes, sprinkling baking soda, spraying deodorant – weren’t cutting it.
The two researchers then turned to science. The culprit, they knew from existing research, was Kytococcus sedentarius, a bacterium that thrives in sweaty shoes.
Their experiments showed that a short blast of ultraviolet light killed the microbes and banished the stink.
“In India, almost every household has a shoe rack of one type or another, and having a rack which keeps the shoes smell-free would give a great experience,” the authors noted in their paper.
They saw “smelly shoes as an opportunity for re-designing the traditional shoe rack for a better user experience”.
The result? Not your average ergonomics paper – and just the kind of delightfully oddball idea: a prototype for a UVC light-equipped shoe rack that doesn’t just store shoes but sterilises them. (UV covers a spectrum, but only the C band has germicidal properties.)
For the experiment, the researchers used shoes worn by university athletes, which had a pronounced odour. Because bacterial build-up is greatest near the toe, the UVC light was focused there.
The study measured odour levels against exposure time, and found that just 2–3 minutes of UVC treatment was sufficient to kill the bacteria and eliminate the foul smell. It was not simple: too much light meant too much heat, which ended up burning the shoe rubber.
The researchers didn’t just point a UVC tube light at the shoes and hope for the best – they measured every whiff.
At the start, the odour was described as “strong, pungent, rotten-cheese-like”. Two minutes in, it had dropped to “extremely low, mild burnt-rubber smell”. By four minutes, the foul stench was gone, replaced by an “average burnt rubber” scent.
Six minutes later, the shoes remained odour-free and comfortably cool. But push it too far – 10 to 15 minutes – and the odour gave way to “strong burnt rubber” while the shoes got hot, proving that even in science, timing is everything.
In the end, the two proposed a shoe rack fitted with a UVC tube light. Nothing came of it until the US-based Ig Nobel Prize took notice and got in touch.
There are Japanese biologists who painted cows to ward off flies, rainbow lizards in Togo with a fondness for four-cheese pizza, US paediatricians who found garlic makes breast milk more appealing to babies, and Dutch researchers who discovered alcohol sharpens foreign-language skills – though it leaves fruit bats bumbling in flight.
There’s also a historian who tracked his thumbnail growth for 35 years, and physics researchers exploring the mysteries of pasta sauce.
Winning for stinky shoes, it seems, has only raised the bar for the Indian researchers.
“Beyond recognition, it’s put a burden on us – we now have to do more research on things people don’t usually think about. Ask questions,” says Mr Kumar. In other words, today’s smelly sneakers could be tomorrow’s groundbreaking science.
