Anyone forced to visit an overused and under-cleaned Porta Potty knows that the stench can be enough to drive people away, no matter how bad they have to go. In the U.S. and other parts of the world with developed sanitation systems, using these facilities is an occasional hassle reserved for music festivals, county fairs and high school football games.
In other parts of the world, however, stinky public toilets are more than just a nuisance—they're a public health crisis, reports Cassie Werber at Quartz. Roughly 2.4 billion people live without a toilet. And while villages and NGOs often build large pit latrines to keep human waste from contaminating waterways, forests and agricultural areas, the stench of those piles of poop can be so overwhelming that many people choose to relieve themselves in the open rather than subject themselves to the olfactory assault.
To tackle this problem, the Bill and Melinda Gates Foundation partnered with the Geneva-based scent maker Firmenich who are working to create a chemical "perfume" that can neutralize the poop stench—supposedly encouraging more people to use the smelly toilets.
The partnership was born from Gates' recent visit to firm in celebration of World Toilet Day, an international event that aims to bring attention to global sanitation issues. The chemistry of pit latrines is much more complex than one might think, Gates writes on his blog. There are over 200 chemical compounds found in feces and urine, which change and combine to form various awful smells.
To understand this chemical stew, Firmenich, which makes scents for Ralph Lauren among others, collected samples from latrines in Kenya, India, Uganda and South Africa and isolated four main chemicals responsible for the stench: indole, p-cresol, dimethyl trisulfide, and butyric acid. The company then created synthetic “perfumes” that mimic the stinky toilets. Armed with the “poo”rfume, the researchers have investigated the best ways to mask the odor-causing chemicals, coming up with an odor-neutralizing compound that Gates tested first hand. He reports that it completely masked the smells.
“The approach is similar to noise-canceling headphones,which many people use to block out jet engine noise on flights,” writes Gates. “Likewise, the ingredients in the fragrances developed by Firmenich inhibit the activation of the olfactory receptors sensitive to malodors. By blocking the receptors, our brains do not perceive the bad smells.”
The odor-inhibitors work well in the lab, but the next step is testing the chemicals at latrines in Africa and India to see if they can stand up to the real deal.
“Because smell was so central to solving this serious public health issue, we knew we could be part of the solution,” Geneviève Berger, Chief Research Officer of Firmenich says in a press release. “The call for action was clear to us, not only because we had the science to counter bad smells, but also, because it resonated with our DNA to have a positive impact through our business and improve people’s quality of life.”