What is a Swiss perfume company - which created fragrances for Giorgio Armani, Hugo Boss, Ralph Lauren and Dolce&Gabbana - doing creating a "poop perfume"? And why has Bill Gates, who took to Twitter this week to promote the new fragrance, been sniffing it?
Answer: Together, they are working to improve sanitation in the world's poorest countries.
The statistics provided by Gates are staggering. Around the world, one billion people have no access to toilets, so they defecate out in the open. Another three billion have toilets, but their waste is dumped untreated, where it seeps into water and food supplies. And each year, about 800,000 children under 5 die from diarrhea, pneumonia and other infections caused by unsafe water and poor sanitation.
Bill Gates says that while millions of new toilets are being built around the world, many of them don't get used because they smell so bad.
With more than a century of experience creating perfumes and analysing odours, Firmenich investigated a basic question - why do toilets smell so bad?
The team isolated the four chemical culprits responsible for producing the awful stench, and then recreated it in the lab using synthetic compounds. They then unleashed the smell on Gates, when he visited their laboratory.
"I put my nose up to a glass sniffing tube in Firmenich's research facility and I was hit by a blast of foul-smelling odours. It smelled as bad as the worst toilets I've ever visited," Gates wrote on his blog GatesNotes.
Firmenich then used this "poop perfume" to develop fragrances that block certain olfactory receptors in our noses, making us unable to register the bad smells.
"In the long history of battling disagreeable odors, from sweaty armpits to wet dogs, the world has largely relied on one solution to the problem," writes Gates. "We use pleasant fragrances to cover over the malodors we want to hide - the olfactory equivalent of sweeping dirt under a rug.
"Firmenich wanted to try a different, more innovative approach to this age-old challenge. They wanted to attack the problem on a molecular level at the connection between our noses and our brains."
It works in a similar way to noise-canceling headphones which people use to block out airplane noise on flights. The ingredients in the fragrances block the olfactory receptors which pick up bad odours, so that your brain doesn't perceive foul smells.
Gates tested out the odour-blocking perfume first-hand.
"I was invited to push my nose into a glass sniffing tube and breathe in a mixture of the poop perfume I had just experienced and one of the new odor-blocking fragrances," he writes. "It smelled pretty good. There was no evidence of repulsive odor I had experienced earlier. Instead of stinky sewage, sweat, and ripe cheese, I sniffed a pleasant floral scent."
Backed by the Gates Foundation, Firmenich are now launching pilot projects in India and Africa to find out whether the new fragrances will make people use toilets and pit latrines more, and whether it is more effective as a spray, a powder, or some other form.
"The ultimate goal is to make the product affordable and easy to use," says Gates.