For air travellers

All too  often,  travelling by plane can  leave you    feeling  exhausted and dried  out by the  time you  arrive to  your  destination. That is a result of an onboard dehydration. The air inside the cabin of a plane usually has a humidity level of 10 to 20 percent which is lower than that of the driest desert on Earth.

Ever wondered:  

Why did you get a splitting headache that lasted the whole flight? 
Why did your skin go from "perfect" to dry and wrinkled within a few hours?
Why did you feel so exhausted?

THE ANSWER: Because the air drawn into the plane to pressurize it comes from extremely dry, high-altitude regions of the atmosphere.