In commercial airplanes, the cabin pressure is typically maintained to simulate conditions at an altitude of about 6,000 to 8,000 feet. This corresponds to a cabin pressure of around 8.0 psi, even when the aircraft is flying at much higher altitudes, such as 30,000 to 40,000 feet. This pressure level is comfortable for passengers and reduces the risk of hypoxia or other altitude-related health issues.