How Altitude Affects Your Body
As you climb higher, the air becomes thinner. At sea level, the atmospheric pressure is approximately 101.3 kPa, with oxygen making up about 21% of the air. As elevation increases, total atmospheric pressure drops, which means every breath delivers fewer oxygen molecules to your bloodstream.
Understanding the Results
Oxygen Partial Pressure (PpO2): The pressure of oxygen in the air you breathe. This is the primary factor driving how much oxygen enters your lungs and blood.
SpO2 (Blood Oxygen Saturation): The percentage of hemoglobin in your blood that is bound to oxygen. A healthy resting SpO2 at sea level is 95-100%. Below 90% is considered hypoxic.
Breathing Rate: Your body compensates for lower oxygen by breathing faster. This increases energy expenditure and can lead to hyperventilation if ascent is too rapid.
Altitude Zones Reference
- 0–1,500m: No significant effect on most people
- 1,500–2,500m: Mild altitude sensation; some breathing changes
- 2,500–3,500m: AMS possible without acclimatization
- 3,500–5,500m: Significant physiological challenge; acclimatization essential
- 5,500–8,900m: Extreme altitude; "death zone" above 8,000m