Tlme of useful
consciousness
Altitude (ft) without oxygen

40,000 15 seconds
35.000 20 seconds
30,000 30 seconds
28,000 1 minute


How, then, can someone like Ed Viesturs repeatedly climb the tallest
mountain peaks in the world without supplemental oxygen? Is it because of
the slower ascent and the time spent acclimating to the higher altitudes?

John K.