Avalanche Burial Facts and Statistics

Asphyxia due to burial is the leading cause of death in avalanche accidents. When a person is buried by snow, they face the risk of being deprived of oxygen, leading to asphyxia. This accounts for roughly 75% of all avalanche fatalities.

Asphyxia is a chemical form of suffocation where rebreathing of air from a confined source of air results in an eventual reduction in oxygen content and saturation of carbon dioxide.

Buried victims under the snow have 10 minutes to be rescued before the risk of asphyxia rapidly increases. (Rauch, Brugger & Falk, 2024; Haegeli et. al, 2011)

Analysis of historic avalanche data in Switzerland and Canada have both concluded that asphyxia begins at 10 minutes - this is a new confirmation, as early Swiss data published in 1994 showed that asphyxia began after 15 minutes.

In these "avalanche survival curve" analyses, the asphyxiation period is the steepest part of the curve where survival chances decrease rapidly. This period can now be considered between 10-35 minutes, where 6 out of 10 asphyxial deaths have historically occurred.

Critical burial is the complete immersion of the head under the snow after being caught in an avalanche.

Analysis of avalanche accidents has estimated a 47% likelihood of critical burial after being caught in an avalanche. Critical Burial has a 44% mortality rate, assuming there are no safety systems which delay the onset of asphyxia.

Total mortality of avalanche accidents where there are no safety systems to reduce burial or delay apshyxia is estimated at 22%.

Between 1985 and 2023, only 12% of those who were critically buried in an avalanche were reported to have had obstructed airways, where the mouth and nose were full of snow. 41% were explicitly reported as "patent", or open airways. The remaining 47% of victims did not have reporting on their airways.

Based on these findings, we can say that open airways have been 3.4x more prevalent than blocked airways in avalanche burial. There is a big opportunity to improve future analysis by improving data collection after avalanche rescue.

The depth of burial also plays a critical role in asphyxia-related fatalities. Victims buried deeper in the snow face higher risks of asphyxia, with survival rates decreasing significantly. For example, the chances of survival for victims buried less than 1 meter is around 90%, while the survival rate for those buried deeper than 2 meters drops to less than 30%.

The use of avalanche safety equipment, such as transceivers, shovels, and probes, is crucial in locating and extricating buried victims quickly to minimize the risk of asphyxia. Studies have shown that the chances of survival increase to over 90% when victims are located and rescued within 10 minutes using these tools.

Proper education, training, and preparedness are essential in preventing avalanche accidents and minimizing the risk of asphyxia. Understanding avalanche terrain, and weather conditions, and practicing safe travel techniques can help prevent accidents and improve survival rates by reducing the risk of burial and subsequent asphyxia.

Asphyxia due to burial is the leading cause of death in avalanche accidents, and the duration and depth of burial play crucial roles in survival rates. Using avalanche safety equipment and proper education and training are vital in preventing accidents and minimizing the risk of asphyxia in avalanche incidents.