Ever noticed just how much you feel the need to fart while travelling on a airplane?

Or how about that vacuum of putrid odour that wafts over your complimentary breakfast after take-off.

On ground level, we break wind around ten times a day, and expel about one litre of gas.

The gases are brewed from food that has failed to be absorbed by the gut and produce nitrogen, carbon dioxide, and hydrogen.

But our trump tally grows when we’re in the air.

Clinical professor Jacob Rosenberg, of University of Copenhagen, explains that its frequency on planes is simple physics.

He said: ‘The pressure drops and the air must expand into more space.’

That one litre of gas inside of us now needs to fill a 30 per cent bigger volume.

This leads to that nasty bloating feeling – a common problem for pilots – and the urge to blow-off.

More than 60 per cent of pilots report regular abdominal bloating. That’s much higher than the average for office workers.