Why is it harder to breathe when climbing up a high mountain? The air pressure increases, the air has more moisture, the air compresses the lungs, or the air is thinner

Answer 1

The air is thinner at higher altitudes, which is the main reason why it is harder to breathe when climbing up a high mountain. As you ascend to higher elevations, the atmospheric pressure decreases, meaning there is less oxygen available in each breath you take. This lower oxygen content makes it more challenging for your body to meet its oxygen demands, resulting in difficulty breathing and sensations of breathlessness. Additionally, the decrease in air pressure can also cause the lungs to expand less, making it feel like they are being compressed. It is important to acclimatize properly when climbing at high altitudes to allow your body to adjust to the reduced oxygen levels.