Silent but deadly – farts explained

By Sophia Giarrusso, Class of 2020.


I’ve been wracking my brains the past week trying to think of an interesting topic to write about. A topic that will be useful to my readers in their everyday lives.

So, I decided to get some advice from my boyfriend’s brother.

I approached him this morning and said, “Bill, what is something that you’ve always wanted to know in your everyday life, that is scientific?

He replied, “….how does food pickling work? Like, why do we pickle things? And what’s the deal with vinegar?

Okay… I coaxed him some more.

“What else? Has anything unusual happened to you recently that you couldn’t explain, but science can?”

He pondered for a while and replied, “…WHERE are all the bubbles coming from in my fizzy water? And HOW does shampoo work? Do you actually need it? And where does all our recycling go? OH, and WHERE does that weird sound come from when you open one window while driving?”

And then he hit the jackpot…

“…and why do some of my farts linger in the room longer than others?”

Now THAT was a question I wanted an answer to, as well as what that strange sound in the car is. I might look into that next week.

What is a fart?

A fart is made from air (oxygen and nitrogen) that is swallowed with food. Farts also contain carbon dioxide, methane and hydrogen which are created during digestion.

Methane and hydrogen are flammable gasses, which is why you can light your farts!


Why do farts smell?

The diverse aroma of farts is the result of what you eat, the bacteria in your gut, and your body’s ability to transform raw materials into nutrients and energy.

Farts also contain small amounts of hydrogen sulfide (also flammable) and ammonia. 

Brussel sprouts
Fart bombs

What you eat

Foods high in sulfur like red meat, chicken, legumes, eggs, Brussels sprouts, cauliflower, and cabbages will make your farts stinkier.

Even fizzy water, and other carbonated beverages, can MAKE you fart more; the carbon dioxide you ingest has to come out somewhere, either as a belch or a toot.


Bacteria in the gut

Bacteria in the large intestine help break down food that was too difficult for your stomach and small intestine to digest. These can include brussel sprouts, legumes, and foods high in fiber. The bacteria in your gut will ferment these pieces of food which produce gas… farts!



The gastrointestinal tract transforms raw food into nutrients and energy for your body. Digestive juices, enzymes, hormones, blood, and nerves all work together to break down food.

Digestive juices are excreted from the pancreases, gall bladder, and liver which help dissolve and break down raw materials. Carbohydrates are broken down into glucose, fats into fatty acids and glycerol, and protein to smaller amino acids.

Food that the body can’t break down by itself can make your farts smellier. These are often fiber-rich foods like beans, oatmeal, and whole-wheat products. This is also the case for people with lactose intolerance who lack the enzyme lactase which breaks down lactose in dairy products. 


Lactose nightmare

Why do Bill’s farts linger?

It depends on the composition of gasses in your fart. Generally, if there is more hydrogen sulfide in the fart it will linger in the air for longer, and this comes back down to what you’re eating.

It also depends on the size of the room you fart in, the clothes you’re wearing (clothes act as a filter), and the sensitivity of your nostrils.

For example, if you dutch-oven your friend, they might claim that the smell is lingering for longer because the ‘poo particles are stuck in their nose’…


To conclude, farts linger because of our digestive system, fermentation by bacteria in the large intestine, and what you decide to have for dinner.

So, the perfect fart to leave in an elevator would be a combination of red meat that’s been brewing in your guts for two days, plus some brussel sprouts, a side of cabbage, and a glass of milk.

If you have any fart questions, feel free to leave them in the comments below.