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To the Editor:
—In the April 17, 1954, issue of The Journal (page 1353) the "Code for Protection Against Lightning," compiled by the National Bureau of Standards, suggested in part that shelter from lightning should be sought in a cave. Despite the recognized reliability of the Bureau of Standards, it appears that, in this case, it has been misled by the scarcity of physical studies in North American caves—a deplorable situation that the National Speleological Society is attempting to correct. Studies by European speleologists have revealed that conductivity and degree of ionization of cave air generally exceed that of outside air (British Caving, Cullingford, C.H.D., editor, London, Routledge & Hegan Paul, Ltd., 1953, p. 151), and it is their belief that this creates a potential lightning hazard. It is an empirical observation that trees near the mouths of caves in certain French forests are more frequently struck by lightning than
Halliday WR. PROTECTION AGAINST LIGHTNING. JAMA. 1954;155(9):859. doi:10.1001/jama.1954.03690270055029