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San Francisco has a crazy plan to fight pee stink with bacteria-eating enzymes

San Francisco has a crazy plan to fight pee stink with bacteria-eating enzymes


Urine trouble

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The Bay Area Rapid Transit (BART) system is taking aim at its number one problem — with a new strategy designed to contain the puddles of urine and eliminate lingering pee smells inside its elevators.

Elevator shafts are basically stink-generators

The overhaul will include testing a prototype odor-eating spray called the "Urine-B-Gone System" currently installed in the elevator at Civic Center Station. The lavender scented, enzyme-based spray is misted hourly into the shaft from a grid of automated puffers. But does something that sounds like an industrial-scale air freshener actually stand a chance against BART’s intractable funk?

It’s possible, say microbiologists Ilana Brito and Jack Gilbert. But in a rail system where public toilets in ten stations have been closed for over a decade, there might be an even simpler way to keep the elevators free of bodily fluids.

Elevator shafts are basically stink-generators. They’re dark, they’re damp, and they’re hard to clean. The deepest part of the shaft, called the pit, is the worst culprit. It catches all of the crap that drips, drops, or flows down it. Rising tides, underground springs, and storm water can also wash into the pit from below. The waste and water stagnating down there creates a veritable soup of microbes.

These microbes feed on the pit’s garbage — including the nitrogen and fatty molecules in urine — and produce waste of their own. This is the source of the ongoing stink. That’s right, don’t blame the pee, says body-odor expert George Preti, a scientist at the Monell Chemical Senses Center in Philadelphia. Pee is usually pretty odorless when it leaves the body (unless the urinator recently ate foods like asparagus or took certain medications).

Getting rid of the stagnant water and killing the microbes could help de-stink the elevator shaft — which is exactly what BART has done. The elevator retrofit crew recently installed a water-proofing and water-pumping system called a Fit Pit at the base of the Civic Center elevator shaft to keep it as dry as possible.

We haven’t been able to learn much about the Urine-B-Gone system yet. (Since "this is just in the testing phase they don’t want to release all the details yet," BART spokesperson Alicia Trost told The Verge in an email.)

From Trost’s description, we can guess that it’s something like the BrandMax Triple Enzyme Cleaner. Its ingredient list includes a detergent, which could kill bacteria by destroying the thin membrane that separates their insides from the outside world. The list also includes different kinds of enzymes that break down proteins, starches, and fats. These could kill bacteria by digesting these kinds of molecules in the microbe’s outer coat, says Ilana Brito, a microbiologist at Cornell University. They might even be able to digest and eliminate the smelly molecules themselves, adds Jack Gilbert — a microbial ecologist at Argonne National Laboratory in Illinois.

That’s right, don’t blame the pee

"I doubt this process would produce anything akin to a complete sterilization, but it might help to remove the odor," says Gilbert in an email to The Verge. "This is definitely needed in some of the stairwells in Chicago as well."

So why not just go nuclear and mist bleach down the elevator shaft? For one thing, bleach is corrosive and could damage metal and plastic parts in the elevator’s machinery. What’s more, bleach and the nitrogen-containing molecules in urine can combine to form molecules called chloramines — which make that nice, clean, swimming pool smell. Chloramines irritate people’s lungs, which is why Michael Phelps’ and Ryan Lochte’s reported pool-peeing habit is more than just gross.

BART’s pee-retrofit will also include reflooring and sealing 80 elevators against future urinary assaults, a project slated to end in April 2017. This is a great first step, but in the end, it’s a BandAid over an ax wound. And that ax wound is the lack of public toilets in BART. After the attacks on September 11, 2001, BART closed the restrooms in ten underground stations; the Department of Homeland Security advised them the one-person bathrooms with their heavy, full length doors were a security risk, according to the San Francisco Chronicle. The BART board of directors, though, has started discussing how to re-open the public toilets at two stations — one in San Francisco, and one in Oakland. The modifications they’re considering include moving the sinks into the public space, and shortening the doors to make it more difficult for anyone to hide illegal activities inside the stalls.

The BART board of directors won’t decide on the bathroom remodel until the fall. And if it’s approved, it won’t be completed until the spring of 2018 — long after BART has tested their prototype Urine-B-Gone system. Regardless of how well it winds up working, giving people a safe, appropriate place to relieve themselves will probably go a long way towards fighting BART’s urine trouble.