system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do airplane cabins need to be pressurised?

So, when the cabin is sealed, the interior pressure is equal to the atmospheric pressure at sea level. When the plane lands, the exterior pressure is equal to the interior pressure. So why does the plane need to be pressurised for the duration of the trip?
gpt
Because the air pressure is extremely low at typical cruising altitudes. You'd lose consciousness from lack of oxygen in less than a minute, and would die not long after. That's why planes have oxygen masks that drop down in case the plane loses pressure. It's also cold. Like, really cold. Upwards of -60C cold.

As an aside, plane cabins are pressurized, but not to sea level. Usually they're pressurized to somewhere between 6,000ft - 8,000ft. This is enough to be comfortable for people while also reducing stress on the aircraft from the pressure differential.