A lifesaver

it is not easy by any chance to survive burial in an avalanche. About one-third of the people caught in an avalanche are killed by injuries from rocks, trees, debris or the force of snow itself. For the remaining two-thirds who manage to remain alive by the time the snow settles, the only chance of survival is a quick rescue. There is a 90 per cent chance of survival after 15 minutes. However, suffocation kills 70 per cent of the people buried alive after 35 minutes. Now, the good news: a simple device called AvaLung, which extracts air from the snow itself, can help the victims survive for up to an hour, giving rescuers the crucial extra time ( New Scientist , Vol 161, No 2169).

People buried in an avalanche rapidly use up the oxygen available in the typically small pocket of air that they have to breathe. Oxygen is fast replaced by carbon dioxide. Moreover, exhaled air also contains moisture. This condenses into water and then freezes into a suffocating