Three Vancouver doctors are urging those with portable CD and MP3 players of a potential danger, after a local man was seriously injured while jogging in a thunderstorm.

The incident happened the summer of 2005. Witnesses saw the 37-year-old man thrown almost 2.5 metres after a tree he was running by was struck by lighting. The jogger had been listening to his iPod at the time.

The patient suffered second-degree burns to his chest and left leg, and burns on his neck and inside his ear canal.

Both of the man's eardrums were ruptured, and he suffered serious hearing loss and fractures in the jaw region.

Eric J. Heffernan, Peter L. Munk, and Luck J. Louis of the Vancouver General Hospital published their report, Thunderstorms and iPods -- Not a Good iDea, in today's issue of the New England Journal of Medicine.

While the report says the use of an electronic device such as an iPod may not increase the chances of being struck by lightning, in this case, the combination of sweat and metal earphones directed the current to and through the patient's head.

The doctors said while people can be struck directly by lightning, it is more common for lightning to jump to a person from a nearby object, such as a tree -- a phenomenon known as a side flash.

Opisthotonic muscle contraction may project the victim some distance, leading to further injury from blunt trauma, doctors said.

Because of the high resistance of skin, lightning is often conducted over the outside of the body (an effect known as a flashover), but sweat and metallic objects in contact with the skin can disrupt the flashover, leading to the internal flow of current and causing severe injuries.

Doctors said the jaw fractures the jogger suffered were probably caused by muscle contraction since there were no external signs of injury to the face.

There have been other recent warnings for potential injury caused by MP3 players. Some of them are:

• Temporary or permanent hearing loss due to the prolonged listening of loud music;
• Repetitive strain injury in the fingers from using the scroll-wheels and buttons; and
• Injury from the leakage of the device's toxic chemicals when the players are heated.

Safety officials have also warned of the dangerous and potentially deadly scenarios that can occur on the roadways when pedestrians and cyclists are listening to MP3 players and not paying attention to their surroundings.

Police and school administrators have also warned against the dangers of children being mugged while carrying the devices.