One of the main problems faced by climbers is trying to climb too quickly. From a medical perspective, we are climbing in very high altitude (up to 4,061m). At sea level, the standard barometric pressure is 101 kPa. At 4,061m on the summit of Gran Paradiso, the standard barometric pressure is 65 kPa. This lower oxygen pressure means that there are fewer oxygen molecules in the same volume of air - there is only 64% of the oxygen available compared to sea level. 

Your body reacts to this lower oxygen level in a variety of ways - for example, your respiration (breathing) rate increases, and your body starts to generate more red blood cells. The respiration increase begins immediately, but the production of extra red blood cells takes longer. We recommend that you discuss with your GP the option of using diamox (acetazolamide) to help prevent Acute Mountain Sickness (AMS).