•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 of Oxygen)
•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.
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