When people go climbing to the high altitude, there are usually two durations. One is for staying at high altitude for a short term. First of all, the rate of breathing would increase constantly which is known as hyperventilation, which means to get more oxygen to the alveoli, it may cause other diseases such as respiratory alkalosis, it will not strengthen the respiratory rate until oxygen is requiredCite error: Invalid
name cannot be a simple integer. Use a descriptive title .One the one hand, hyperventilation means human body got a low oxygen level, which is known as hypoxia. In fact, the proportion of oxygen still remains at 21%, however the air pressure has decreased with altitude so does the concentration of oxygen molecules per unit volume of air. As a strong evidence, it indicates that it is difficule to get enough oxygen. On the other hand, the most siginificant progress of hyperventilation starts at partial pressure oxygen in air at high altitude decreasing. A decrease of oxygen gradient between environment and cells would ensue. Subsequently human’s breathing rate and the depth of breathing would show an upward trend. At the end of the whole progress, partial pressure oxygen at alveoli increases so that improve the supply of oxygen to cells. 
- ↑ Stroncek, D., Byrne, K., Noguchi, C., Schechter, A. and Leitman, S. (2004). Increasing hemoglobin oxygen saturation levels in sickle trait donor whole blood prevents hemoglobin S polymerization and allows effective white blood cell reduction by filtration. Transfusion, 44(9), pp.1293-1299.