Already after 3 hours of flying the relative humidity is as low as 5 % in a typical First Class Cabin. In an airplane, the only humidity contribution comes from the people on-board. Ironically, the lower seat density – the lower humidity – means that the premium seating goes with the driest air.
According to NBC, Dr. Tom Finger, Professor at the University of Colorado School of Medicine and co-director of the Rocky Mountain Taste and Smell Center, claims that:
“Dry air doesn’t help our sense of smell, either. Typically, odorants are transported to olfactory receptors in the nose via the mucus lining. When the nasal cavity is dried out, the efficiency at which odorants are detected by the brain is reduced. When you “lose the olfactory component,” explains Finger, “you lose much of the flavor component of food.”
It is medically proven that extremely low RH levels make the human body functions abnormally being more sensitive due to dehydration and human senses, such as taste, are very different. Even short time exposure to extremely dry air affects the nose and mouth. In fact, up to 80% of what we consider taste is actually derived from smell. The taste is built up around many very complex co-existing factors.
Why food tastes differently in the sky can partly be explained by:
– Dry air changes the taste in the mouth
– Dry air alters the viscosity of the saliva
– Dry air result in swelling of the mucous membranes
– Dry air modifies the ability to vaporize into the nose
– Dry air de-hydrates nasal cavity affecting the sense of smell (innervation/olfactory nerve)
– Dry air decreases volatility of odor molecules
Further, extremely low-RH increase risks for static discharges and ageing of materials.