Even on the ground, we all pass a surprising quantity of gas every day. According to one estimate, the average person breaks wind 10 times every 24 hours, expelling about 1 litre in total. The gases are brewed from food that has failed to be absorbed by the gut, and so is fermented by bacteria, which produce nitrogen, carbon dioxide, and hydrogen – along with more odorous, sulphurous compounds.

It may be a universal experience, but as Rosenberg combed the medical literature, he found that there are some surprisingly prevalent misconceptions surrounding our wind. Despite popular belief, studies show men are not more flatulent than women, for example (though they may be more public about it); in fact the same study from the late 90s found women’s flatulence has a higher concentration of the smelly sulphurous compounds, and was rated as having a more potent odour by a few unlucky judges. And although beans may be known “as the musical fruit”, a recent experiment found that it is not nearly as inflammatory as most would believe, and its effects differ widely from person to person. Foods known to reduce flatulence include fish, rice, dairy products, fish and strained fruit juice – since they leave less waste in the gut for fermentation.

Bloated pilots

But if our flatulence on ground level passes mostly unnoticed (or is at least politely ignored) in day-to-day life, it can become something of an unwanted companion in the confines of an air cabin. Its frequency on planes is simple physics, Rosenberg says. “The pressure drops and the air must expand into more space.” That 1 litre of gas now needs to fill a 30% bigger volume, leading to that nasty bloating feeling. This seems to be a regular problem for pilots – more than 60% report feeling regular abdominal bloating, much higher than the average for office workers.

You could just try to hold it in, of course, but that’s not necessarily a wise idea; besides the discomfort, Rosenberg thinks there could be a slight risk. “If you are young and healthy it’s not a problem, but for a frail old person, it may put strain on cardiac function,” he says.