Final answer:
Passenger oxygen masks are automatically deployed when there is a sudden loss of cabin pressure in an airplane. The masks provide oxygen to passengers in order to prevent hypoxia.
Step-by-step explanation:
The passenger oxygen masks are automatically deployed when there is a sudden loss of cabin pressure in an airplane. This is because at high altitudes, the air becomes thinner and contains less oxygen, which can lead to hypoxia (lack of oxygen in the body). In order to ensure the safety of the passengers, the oxygen masks are designed to drop down from the overhead compartments automatically.
When the masks are deployed, the passengers are advised to pull them down over their noses and mouths, and breathe normally. The masks are connected to oxygen cylinders, which release oxygen when the passengers breathe in. This way, the passengers can continue to breathe and maintain oxygen levels in their bodies until the plane descends to a lower altitude where the air pressure and oxygen levels are normal.
It is important for passengers to follow the instructions provided by the flight attendants and use the oxygen masks correctly, as it can be a life-saving measure in case of an emergency.