After how many hours at the same altitude are AMS symptoms no longer likely?

Acute Mountain Sickness (AMS) symptoms are typically associated with rapid ascents to high altitudes where the body may not have adequate time to acclimatize to the lower levels of oxygen. Generally, after spending an extended period at a high altitude, the risk for developing AMS decreases as the body begins to acclimatize.

Research shows that after approximately 24 to 36 hours at the same altitude, the likelihood of developing AMS symptoms diminishes significantly because the body has had an opportunity to adjust to the hypoxic conditions. During this acclimatization process, physiological changes occur, enabling better oxygen utilization and thus reducing the risk of AMS.

Staying at a high altitude for at least 24 hours often results in improved tolerance, but it's around 36 hours when the body's acclimatization mechanisms are more robust and most individuals will not experience AMS if they remain at a stable altitude. Hence, the choice indicates that the risk of AMS symptoms is significantly lowered after being at the same altitude for 36 hours.