Lightning Injuries

Approximately five fatalities from lightning strike are recorded in Britain each year [1]. Although rare in the Northern European climate lightning strikes increase in frequency toward the equator. Between 1959 and 1994 lightning has been the second largest storm related cause of death in the USA, exceeded only by flash floods [2]. The true incidence of lightning strike is unknown. Approximately 50% of lightning strikes are thought to go unreported [3]. The mortality from lightning strike approaches 30%. Survivors may suffer from long term sequelae.

Is lightning an alternating or direct current?

The electrophysical basis of lightning is complex as lightning is neither direct nor alternating current. It can be regarded as a unidirectional current impulse.

The temperatures within a bolt can be massive – between 8000 and 22000 °C. The energy dissipated when lightning strikes the ground is sufficient to fuse silica resulting in the stone known as fulgurite. Fortunately lightning strike tends to ‘splash over’ the victim. Consequently, deep penetrating burns rarely occur and thermal injury tends to be superficial.

How lightning causes injury?

Direct strike is surprisingly rare, but may have the greatest mortality. More commonly, injury is thought to result from ground current spread: lightning strikes the ground and spreads out to involve those in close proximity. Lightning may also splash sideways from an object, or a victim may be holding onto an object which is struck.

Lightning can produce blunt trauma. A victim may be thrown by muscle contraction or blast trauma may result from an associated thunderclap.

Lightning tends to hit the tallest object and objects which are standing in isolation. Lightning strike can also occur indoors with conduction via electrical wiring or plumbing. Seeking ‘protection’ during an electrical storm beneath a tree or in some form of outdoor shelter may actually increase the risk of being hit.