What is the atmospheric pressure on Mount Whitney?

Mount Whitney, the highest peak in the contiguous United States at 14,505 feet (4,421 meters), experiences significantly lower atmospheric pressure compared to sea level. At its summit, the atmospheric pressure is approximately 60% of that at sea level, translating to around 8.5 psi (pounds per square inch) or roughly 500 mmHg. This reduced pressure can affect climbers, leading to altitude sickness and requiring acclimatization.