Cases of Lightning Strikes during Mountain-Sports Activities: An Analysis of Emergencies from the Swiss Alps

Background: Lightning strikes are a risk during mountain-sport activities. Yet little is known about the prevalence of injuries related to lightning strikes during mountain hiking, backcountry skiing, or high-altitude mountaineering. This study therefore examined the occurrence and characteristics of lightning-strike-related emergencies during mountain-sport activities in the Swiss Alps. Methods: We analyzed 11,221 alpine emergencies during mountain hiking, 4687 during high-altitude mountaineering, and 3044 during backcountry skiing in the observational period from 2009 to 2020. Identified cases were analyzed in detail regarding age, sex, the time of occurrence, altitude, location, the severity of the injury as quantified by its NACA Score (National Advisory Committee for Aeronautics Score), and injury pattern. Results: We found no cases related to backcountry skiing. Eight cases of lightning strikes during mountain hiking (four female and four male) were identified. The mean age was 32.5 ± 17.5 years, the mean NACA Score was 2.5 ± 1.9, and the mean altitude was 1883.8 ± 425.7 m. None of these cases were fatal, and only one victim was seriously injured. Fifteen cases were identified during high-altitude mountaineering (four female and 11 male). The mean age was 38.7 ± 5.2 years, the mean NACA Score was 3.1 ± 2.5, and the mean altitude was 3486.4 ± 614.3 m. Two lightning strikes were fatal. In these two cases, rope partners were injured by a lightning strike (NACA Score = 4). Most cases were on relatively exposed terrain, such as the Matterhorn Hörnligrat or the Eiger Mittellegigrat. Discussion: The typical victims were 30–40-year-old men. It is possible that the lightning strikes are a consequence of a lower risk aversion among these alpinists, which is be supported by the fact that most of the events occurred on famous mountains such as the Matterhorn or Eiger. Furthermore, since most of the locations were on relatively exposed terrain where one could not quickly find shelter, we recommend careful tour planning with serious consultation of the weather forecast and the likelihood of thunderstorms before climbing exposed sections to prevent emergencies related to lightning strikes.