/ 28 January 2011

Myths that kill

Myths That Kill

The colour red doesn’t attract lightning, and covering the mirrors in a house won’t make a difference. Syringa trees aren’t more strike-prone than other tree species of similar height, and a tyre on the roof won’t drive lightning away.

But these won’t make you less safe. It is other myths that can kill.

The thick rubber soles of hiking boots won’t electrically isolate you from the ground and keep you safe — they’ll just melt on to your feet if you’re struck.

It’s the metal enclosure and not the tyres of a car that makes being inside one safe. The forces involved are far too powerful to be stymied by such small elevation — so riding a motorcycle in a thunderstorm is a very bad idea.

The beliefs most likely to kill, though, are the supernatural.

“Many South Africans believe some people can control lightning,” says Estelle Trengove, a Wits lecturer who has worked in the field. “Sometimes the belief is that natural lightning won’t kill you but that man-made lightning can be sent to target you.”

That is where muti buried around the house or rubbed on to the skin comes in. Though harmless in itself, the resulting sense of invulnerability doesn’t help. Also, if you think man-made lightning caused a death, it may seem a good idea to stop the person responsible.
Trengove is studying myths. She believes dismissing them as superstitious nonsense will achieve nothing.

Avoiding a strike
Ryan Blumenthal, a senior specialist at the forensic medicine department at the University of Pretoria, has conducted autopsies on the victims of lightning strikes, examined animals killed by lightning, written academic papers on safety precautions and spoken at schools and clubs about safety in thunderstorms. Yet he boils down all his experience to one catchy phrase: “When lightning roars, go indoors.

“Around the world lightning is the most consistent weather killer and the most preventable,” Blumenthal said. “There’s only so much you can do about a tsunami but with lightning some simple rules will keep you safe.”

The easiest rules to follow also dramatically reduce the risk of injury. Get out of the open, off or out of water and into a house or car with a full metal roof. Once inside, stay away from landline phones and anything plugged into a wall socket.

If you’re caught outside, things get more tricky. Stay well away from trees and anything tall. Get down from the tops of hills and ridge lines.

If you have to sit out a storm, resign yourself to getting wet and crouch down with your feet tightly together and no other part of your body touching the ground.

‘One moer of a bang’
To completely rule out being struck by lightning you need to go a little further. Until three decades ago you could be forgiven for constructing a nuclear reactor or ammunition dump, erecting a really tall copper pole next to it, and congratulating yourself on a job well done.

Then we found out about positive lightning. About 80% of all lightning jumps from cloud to cloud, never presenting a threat, and almost every strike that hits the earth is classic negative-downward, which seeks out the highest available point and adores lightning conductors. A very small number of strikes, however, are positive lightning.

“Sometimes you can hear it,” said Ian Jandrell, a Wits lightning professor. “It goes ‘bang’, ‘bang’, ‘bang’, ‘bang’, ‘bang’, then it goes quiet — and then there’s one moer of a bang. That’s positive lightning, which comes towards the end of the storm when the negative charge has been depleted.”

Positive lightning breaks the rules. It touches down where it pleases, ignoring masts and other high points. It is usually far more powerful and so causes more destruction.

The only way to protect against such strikes is expensive: enclose everything in a grid of interconnected conductors, preferably a tight one, then connect as much of that grid as you can to conductors buried deep in the ground. Then cower inside any time a cloud comes within 100km and you’re safe — at least until we learn something new about the nature of lightning.