How this calculation works
The Altitude Sickness Risk & Oxygen Calculator estimates barometric atmospheric pressure loss, effective oxygen availability percentage, and Acute Mountain Sickness (AMS) clinical risk based on World Health Organization (WHO) and Wilderness Medical Society guidelines.
Mathematical formula and logic
Atmospheric Pressure P = P₀ × e^(-Elevation / 7400). Effective Oxygen % = 20.9% × (P / P₀).
Worked example
At Cusco, Peru (11,150 ft / 3,400 m), atmospheric pressure drops to ~68 kPa (67% of sea level). Effective oxygen availability is only 14.1% (down from 20.9% at sea level). Flying directly carries a High AMS Risk requiring 48 hours of light activity and hydration.
Calculation assumptions
- Standard barometric exponential atmospheric lapse model.
- High altitude defined as 8,000+ ft (2,400+ m); Extreme altitude defined as 18,000+ ft (5,500+ m).
Frequently asked questions
What is Acute Mountain Sickness (AMS)?
AMS is the body's physiological response to reduced atmospheric oxygen at elevations above 8,000 feet (2,400m), characterized by headache, nausea, fatigue, dizziness, and insomnia.
What is the 'Golden Rule' of altitude acclimatization?
Above 10,000 feet (3,000m), limit sleeping elevation gains to no more than 1,000 to 1,600 feet (300 to 500 meters) per day, and take a mandatory rest day every 3 to 4 days ('Climb high, sleep low').
Does physical fitness prevent altitude sickness?
No! High cardiovascular fitness does NOT protect against AMS. Susceptibility is determined by individual genetic hypoxic ventilatory response and ascent speed.
What medication prevents altitude sickness?
Acetazolamide (Diamox) is a prescription carbonic anhydrase inhibitor that acidifies the blood, stimulating faster breathing and accelerating natural acclimatization when taken 24 hours prior to ascent.
What are HAPE and HACE?
High Altitude Pulmonary Edema (HAPE — fluid in lungs) and High Altitude Cerebral Edema (HACE — brain swelling) are severe, life-threatening complications of altitude sickness. Immediate descent to lower elevation is the mandatory emergency treatment.
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