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Dispatches: Avalanche survival rates differ in Canada

Industry statistics based on Swiss curve proven less applicable in Coast Mountain conditions



It's a thought that drives backcountry users to habitually reassess their strategy during every minute spent in the cold, pristine wilds of the Coastal Range. Avalanches are common enough to the steep pitches of B.C.'s terrain, easily wiping vast wilderness expanses clean of trees, rocks and whoever might stand in the way.

A terrifying force with little forgiveness, a snow slide is the top priority on any backcountry expert's mind, even when enjoying the deep, unfettered slopes that draw them there.

It's certainly what has dominated Simon Fraser University researcher Pascal Haegeli's thought process over the past decade.

An avid backcountry skier who did his PhD at UBC under famed avalanche expert Dave McClung, Haegeli is behind a study recently published in the Canadian Medical Association Journal that compares avalanche victims in Canada and Switzerland.

"The motivation of the study was that current avalanche rescue resuscitation guidelines are based on an avalanche survival curve that is only based on Swiss avalanche data," he said during a phone interview from Switzerland.

"We wanted to know whether that curve, and therefore the guidelines, are universally applicable and if not, then if the Canadian patterns are different, then we wanted to know more about the Canadian patterns so that rescue guidelines here can actually be adjusted to more specifically target the issues we have in Canada."

The avalanche survival curve displays a person's chance of surviving a complete burial as a function of time, essentially tying one's chance of survival to duration of burial. Data collected during Haegeli's studies included 301 Canadian and 946 Swiss subjects who had been completely buried in an avalanche. The information pointed to an unsettling conclusion based on three factors - trauma, asphyxia and proximity to trained medical care.

"What we found is that your chance of surviving a burial in Canada is lower at all times than in Switzerland," said Haegeli.

"For burials that are shorter than 10 minutes, in Canada there is a significantly higher rate of trauma than in Europe. We spend a lot more time in the trees while in Europe basically all back country activity is in the alpine."

Around a quarter of all avalanche deaths in B.C. occur from trauma sustained from hitting trees, going over cliffs and the pure violence of the slide itself. Only five to six per cent of European avalanche deaths relate to similar trauma.

Heavy snow conditions due to warmer temperatures in the coastal regions are more likely to contribute to asphyxia than the colder snow of the Rockies, which is comparable to Swiss conditions.