title: Risk of Avalanche Involvement in Winter Backcountry Recreation: The Advantage of Small Groups.
abstract: OBJECTIVE
  Avalanches are the primary hazard for winter backcountry recreationists and cause numerous deaths and injuries annually. Although recreationists usually travel in groups, there is little empirical knowledge on group-related risk factors. This study aims to explore the relative risk of avalanche accidents with respect to group size and to discuss underlying reasons for different risk levels.
  
  
  METHODS
  We compared backcountry usage data in regions in Switzerland and Italy with avalanche accident data in these regions.
  
  
  RESULTS
  We found higher avalanche risk for groups of 4 or more people and lower risk for people traveling alone and in groups of 2. The relative risk of group size 4, 5, and 6 was higher compared with the reference group size of 2 in the Swiss and Italian dataset. The relative risk for people traveling alone was not significantly different compared with the reference group size of 2 in the Italian dataset but was lower in the Swiss dataset.
  
  
  CONCLUSIONS
  These findings are in accordance with avalanche safety recommendations regarding the higher risk of large groups but not regarding lower risks of people traveling alone in avalanche terrain, which is not recommended and requires great caution. Further studies on backcountry usage are necessary to improve our understanding of human behavior and risk factors. New techniques (eg, video monitoring) may be useful for acquiring reliable data on backcountry usage.
authors.affiliation: WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland (Dr Zweifel and Mr Techel). Electronic address: zweifel@slf.ch.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Zweifel
authors.affiliation: EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy (Ms Procter and Dr Strapazzon); Department of Sport Science, Faculty for Sports Science and Psychology, University of Innsbruck, Innsbruck, Austria (Ms Procter).
authors.forename: Emily
authors.initials: E
authors.lastname: Procter
authors.affiliation: WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland (Dr Zweifel and Mr Techel).
authors.forename: Frank
authors.initials: F
authors.lastname: Techel
authors.affiliation: EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy (Ms Procter and Dr Strapazzon).
authors.forename: Giacomo
authors.initials: G
authors.lastname: Strapazzon
authors.affiliation: Swiss Federal Institute of Technology, Zurich, Switzerland (Dr Boutellier).
authors.forename: Roman
authors.initials: R
authors.lastname: Boutellier
mesh_terms: D000059:Accidents / Q000706:statistics & numerical data*; D055875:Avalanches / Q000706:statistics & numerical data*; D016208:Databases, Factual; D006801:Humans; D007558:Italy; D011998:Recreation; D012307:Risk Factors; D012621:Seasons; D012865:Skiing / Q000293:injuries / Q000706:statistics & numerical data; D013557:Switzerland
keywords: avalanche accidents; avalanche prevention; backcountry skiing; outdoor recreation; recreational monitoring