Physiological Factors of Altitude: Oxygen Deficiency
•Proportion of Oxygen in atmosphere- 21%
•Partial pressure of Oxygen decreases with height in
proportion to other gases
•Lungs saturated with water vapor; reduces available
oxygen
•Oxygen in lungs: (ambient pressure – saturation water
vapor pressure at body temp (37C) (63
mb)) * .21
•Sea level (1013 – 63 ) * .21 = 200 mb; 5000 m (540 – 63
) * .21 = 100 mb
•Hypoxia- intolerance to oxygen deficiency
–Humans can tolerate half sea level value
indefinitely
–Symptoms significant above 3000 m (133 mb)
•Standard Atmosphere varies with latitude (4000 m roughly
630 mb equatorward of 30o; 593 mb (winter)-616 mb (summer) at 60o
•Cyclone could drop pressure 10-20 mb; equivalent to
several hundred meters in
elevation
•Grover (1974); Man living at high altitudes. Arctic and
Alpine Environments.