Which gas is primarily associated with hypoxia at high altitudes?

Hypoxia at high altitudes is primarily related to a decrease in the availability of oxygen. As altitude increases, the atmospheric pressure decreases, leading to a reduced partial pressure of oxygen in the air. Although the percentage of oxygen in the atmosphere remains relatively constant at around 21%, the lower pressure means that there is less oxygen available for the body to use, resulting in a condition known as hypoxia, where the body or parts of the body are deprived of adequate oxygen supply.

This is particularly critical for aviation and high-altitude environments, where the body must adjust to lower oxygen levels. Oxygen is essential for cellular respiration, and under hypoxic conditions, vital organs function less effectively, which can lead to impaired cognitive and physical performance, and in severe cases, loss of consciousness or death.

While carbon dioxide, nitrogen, and helium have roles in our atmosphere and body functions, they do not play a primary role in causing hypoxia at high altitudes. Carbon dioxide is a waste product of metabolism, nitrogen is inert at typical pressure levels, and helium, though used in specific applications, does not contribute to oxygen delivery in the body.