Your body in flight : an illustrated "book of knowledge" for the flyer / prepared by the Aero Medical Laboratory, Engineering Division.

United States. Army Air Forces

Date:: 1943

Credit: Your body in flight : an illustrated "book of knowledge" for the flyer / prepared by the Aero Medical Laboratory, Engineering Division. Source: Wellcome Collection.

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$T. O. No, 00-25-13 How an increase in the oxygen content of the air you breathe offsets re- duction in partial pressure may be seen from this example: At 18,000 feet altitude, the partial pressure of oxygen is 80 millimeters, compared to 160 at sea level. If you increase the proportion of oxygen from 21 percent to 42 percent, its partial pressure is again 160 millimeters, To obtain 160 milli- meters of oxygen pressure at 34,000, pure oxygen is needed, An allowance must be made for water vapor in matching breathing conditions found at ground level, Water vapor pressure in the lungs remains constant, and thus contri- butes an increasing percentage of the total as the air pressure is reduced, Above 34,000 feet the oxygen in the blood decreases below normal, even with a supply of 100 percent oxygentothe lungs, The critical point is reached at 40,000 feet where 100 percent oxygen pressure is barely enough to keep the oxygen content of blood within safe limits, The period at which you will remain conscious above that altitude is a matter of minutes, despite your mask, Without a mask, you may, if you do not exercise, keep your senses for thirty minutes at 18,000 feet; but at 25,000, consciousness will last only a few minutes; at 30,000, a minute or less; and at 35,000, thirty seconds or less, No harmful effects will result from breathing pure oxygen during air travel, It will not,as some say, make your teeth brittle or give you pneu- monia, 1-AM-PRESSURE tuat FORCES: OXYGEN: INTO THE-BLOODSTREAM OXYGEN. , | | HAS BEEN ‘ : FORCED INTO ME 2. OVER-40,000/) PRESSURE [(* 1S- INSUFFICIENT _. = NOW-]-AM: TOO WEAK: TO: PUSH: a INTO |-STILLNEED- OXYGEN HERE-]- AM: AGAIN, a -THERE: WASN'T: HALE HUNGRY: FOR: OXYGEN \LENOUGH PRESSURE$