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What Percent of My Farts Stays in My Mattress?

Also, what about my pants?

Let’s say, in a completely, totally, absolutely made-up hypothetical, a man who recently began working from home has taken to working atop his bed, because he lives in a small apartment and his partner takes a lot of very important calls. Let’s also assume that this man, thanks to a healthy and balanced diet, farts a bit more frequently than the average bear

And so, a completely, totally, absolutely legitimate question arises in his mind: Beyond packing his mail-order, memory-foam mattress full of sweat and dead skin, if he were to release a fairly continuous stream of gas throughout the work day, would his mattress be soaked in farts — and if so, for how long?

This guy, of course, is completely, totally, absolutely not me. But allow me to outline the basics for him anyway (after all, whoever he is, he deserves a real answer to a query that affects no less than his marriage, his health, his sleep and his goddamn peace of mind). 

To start with, farts are gaseous byproducts of bacteria in the digestive tract and often consist of oxygen, nitrogen, hydrogen, carbon dioxide and methane — either individually or combined in volatile concoctions like hydrogen sulfide, methyl sulfide or methanethiol. The amount of gas expelled during a single fart can range from that of a bottle of nail polish to a 12-ounce can of soda. Notably, however, these gaseous particles are super small. For comparison’s sake, a tiny sphere of coronavirus is 100 to 1,000 times larger than your typical fart particle — that’s why a fart can penetrate an N95 mask

If you don’t trust the science, check out redditor ATrain1189 as he farts into his Dyson air purifier, which “immediately registers [the fart] as a Volatile Organic Compound and works on filtering the air ASAP”: 

Dyson air purifier immediately registering my fart as a Volatile Organic Compound (VOC’s) and works on filtering the air ASAP from videos

But back to the true topic at hand: Are these farts slowly but surely saturating my — I mean, our hypothetical guy’s — mattress? 

According to a 2005 study in The American Journal of Gastroenterology titled “Effectiveness of Devices Purported to Reduce Flatus Odor,” clothes go a long way in filtering viral and bacterial loads from our farts — by about 17 to 28 percent to be exact. Meanwhile, another study in the British Medical Journal sought to answer whether or not it was safe for surgeons to fart in a sterile environment. Basically, in the same way working from his bed all day might lead to farts filling up our hypothetical guy’s mattress, could surgeons fill up the OR with their farts during a particularly long operation?

To find out, Australian physician Karl Kruszelnicki and microbiologist Luke Tennent devised an experiment where a subject “[broke] wind directly onto two Petri dishes from a distance of 5 centimeters, first fully clothed, then with his trousers down.” Per the published study, “The second Petri dish sprouted visible lumps of two types of bacteria that are usually found only in the gut and on the skin. But the flatus which had passed through clothing caused no bacteria to sprout, which suggests that clothing acts as a filter.” 

“The enteric zone in the second Petri dish was caused by the flatus itself, and the splatter ring around that was caused by the sheer velocity of the fart, which blew skin bacteria from the cheeks and blasted it onto the dish,” the researchers continued. “It seems, therefore, that flatus can cause infection if the emitter is naked, but not if he or she is clothed.” 

To recap, farts are full of noxious gases produced by bacteria in the gut, but most of the particles exhausted from one’s butthole are filtered by their pantaloons. 

What, though, of the rest? 

“The gas molecules, including methane and hydrogen sulfide, will eventually diffuse through the bedding and into the air,” explains Alex Klotz, an assistant professor in the Physics Department at California State University, Long Beach. Remember, fart particles are super tiny, so while they might bounce around your mattress for a few seconds, they’re not going to stay there much longer than their smell lingers. Plus, as Trevor A. Makal, associate professor of chemistry at the University of Virginia’s College at Wise, tells me, “Most of the gases in farts are less dense than air, so they naturally travel upwards into the atmosphere.”

That said, Klotz warns against thinking of mattresses as bacteria-resistant. “There are other things that come out of your butt, too — including small particles of feces, droplets containing bacteria, etc. — and those stay embedded in your sheets,” he tells me. “Liquid droplets especially can stay on fibrous materials for as long as it takes fabric to dry completely.”

Still, in terms of farts, while he “doesn’t doubt that a fraction of what comes out of your butt will penetrate through your pants and sheets into the mattress, it would be a small fraction of the overall amount.” 

“So, my gut says you won’t find fart matter deep in a mattress,” he concludes.  

Sleep easy, my hypothetical friend.