"Dan" wrote in message
oups.com...
Obviously, above a certain altitude, judgement would be impaired,
however what altitude and exposure time is required for permanent
damage to occur?

Dan


The answer appears to be "It depends"... Acclimation can make a big
difference. People climb Everest without O2, but they spend weeks
acclimating and I've read different opinions brain damage on them.

Smoking, the altititude you live at, etc. make a big difference when you
fly. Some examples:

http://www.smartcockpit.com/operatio...ompression.pdf
The effects of hypoxia may vary from one person to the next,

depending on the person's health, state of fatigue, state of

physical fitness and how much activity an individual must

perform. (Pilots and flight attendants require more oxygen

during an emergency than typical, healthy, seated passengers.)

Because the eyes and the brain have a high metabolism and

cannot store oxygen, they are most sensitive to oxygen

depletion; the first measurable decline in the body's functioning

occurs in sight, with some loss of night vision at altitudes as

low as 5,000 feet.22 After several hours at 10,000 feet, many

people experience a "measurable deterioration" of their mental

abilities and physical dexterity. At 18,000 feet, the mental

deterioration may be followed by unconsciousness; the TUC

at that altitude is about 15 minutes. At 25,000 feet, the TUC

may be as little as three minutes, and in some situations,

exposure to cabin altitudes of more than 25,000 feet without

supplemental oxygen for more than two minutes might result

in permanent brain damage. At higher altitudes, the TUC

decreases rapidly; at 40,000 feet, for example, the TUC may

be 15 seconds or less.

Other physical effects of decompression include the painful

expansion of gases in body cavities - the stomach and

intestines, the joints, diseased areas beneath the teeth and inside

decayed teeth - and pain in the middle ears and the sinuses

as the body adjusts to the pressure change.19 If the

decompression is slow, one of the early symptoms of hypoxia

is a blue tinge on the lips and under the fingernails; the color

change is a result of the reduction of oxygen in the hemoglobin

of red blood cells.23

see also:

http://ntsb.gov/ntsb/brief2.asp?ev_i...IA093& akey=1

http://www.mos.org/Everest/exhibit/physiology.htm

--
Geoff
The Sea Hawk at Wow Way d0t Com
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