Answer
Aircraft fly at the high altitude where atmospheric pressure is low because pressure reduces with altitude consequently partial pressure of oxygen also reduces with altitude. Lower oxygen level leads to hypoxia i.e. tension in the lungs and brain, loss of consciousness, and ultimately death.
Hence passenger airplane cabins normally pressurized to create a safe and comfortable environment for passengers and crew flying at high altitudes.
Work Step by Step
Aircraft fly at the high altitude where atmospheric pressure is low because pressure reduces with altitude consequently partial pressure of oxygen also reduces with altitude. Lower oxygen level leads to hypoxia i.e. tension in the lungs and brain, loss of consciousness, and ultimately death.
Hence passenger airplane cabins normally pressurized to create a safe and comfortable environment for passengers and crew flying at high altitudes.