Mobile telephones and lightning strikes

Vernon Cooray

[ Warnings]

* Avoid standing in an open space without any other tall objects

* Not to use the standard telephone during thunderstorms

* Metal objects worn by the victim will melt during a lightning strike

Whenever there is a lightning strike to a building or a house, large electric current may enter into the telephone system. These current can jump into the head of a person who is being using the telephone at the time of strike causing severe neurological injuries.

Many of the lightning related accidents taking place inside houses are mediated by current either flowing in the telephone system or the power system. For this reason, it is recommended not to use the standard telephone (the ones with handsets plugged into outlets) during thunderstorms.

In 2008 a teenage girl was struck by lightning while using a mobile telephone in the UK. She had a cardiac arrest and had to be resuscitated. In the ear she was holding the phone, she had a burst eardrum. The event left her with severe physical difficulties and emotional and cognitive problems.

This incident had stirred the imagination of doctors in the UK to issue a warning not to use mobile telephones during thunderstorms.

Lightning had been known to cause death, cardiac and respiratory arrest, rupture of eardrum and neurological injuries long before the mobile telephones were invented. The injuries received by the girl mentioned above are not unusual but are the norms in lightning injuries.

Electrical discharge

A human being standing in an open space without any other tall objects will attract a typical lightning flash from a distance of about 25 m. Usually, the lightning flash terminates on the head; the highest point of the body. From the point of contact, the lightning flash injects a current into the body and this current passes through the brain and other sensitive parts of the body causing injuries.

Fortunately, the current in the lightning flash starts with a small value but increases to a very large value in a few millionths of a second.

Thus the current passing through the body too starts with a small value and increases rapidly. But, as the lightning current passing through the body increases, the resistance of the body to the flow of current through it creates an electrical discharge along the skin of the body and at that moment the current of the lightning flash jumps out of the body and starts to flow along the electrical discharge created along the skin of the body.

This phenomenon is called flashover. It is this event that makes it possible for majority of lightning victims to survive. How quickly the path along the skin is created or how quickly the lightning current jumps out of the body depends on the wetness and the saltiness of the skin. Metal objects worn by the victim could also help creating flashover.

Mobile telephones

A mobile telephone cannot influence the chance of a lightning strike to a human. Actually, mobile telephones are too small to influence the path of a lightning strike. Those who were struck by lightning while using a mobile phone happened to be at the wrong place during a thunderstorm. The mobile telephones had nothing to do with those lightning strikes.

The mobile uses radio waves to communicate. In some Internet sites it is stated that lightning flash can follow these radio waves. This is pure fiction and has no scientific background.

As mentioned above the metal objects worn by a person could indeed help the process of flashover and may even help the victim to survive a lightning strike.

The mobile telephones also act as any other small metal objects located outside the body (such as jewellery) and could even help in creating a life saving ‘flashover’ along the body. On the negative side the mobile phone can explode when the large lightning current passes through it and the flying pieces of the exploded mobile can cause injuries.

Furthermore, the metal objects worn by the victim will melt during a lightning strike and may cause burn injuries. But, these injuries are not life threatening as the injuries caused by the current flowing inside the body.

One of the serious consequences of a lightning strike is the cardiac or respiratory arrest (or both). In many cases the victim can survive if he or she receives medical attention immediately.

If you happen to be in the vicinity of such a victim take out your mobile telephone and call an ambulance immediately. Do not hesitate thinking that using your mobile telephone will lead to another lightning strike. The life of the victim depends on your quick action.

(The writer is Professor of Discharge Physics and Lightning Research Uppsala University, Uppsala, Sweden)