Technology & Science

Lightning: Health risks of nature's electrifying jolt

Lightning kills an average of 10 Canadians a year and seriously injures another 125. There are some easy steps you can take to help minimize your risk when bad weather approaches. Above all, 'if it roars, go indoors.'
Neil Fraser watches as lightning hits beyond a church in Rosser, Man., as a severe electrical storm made its way across southern Manitoba in July 1995. ((Marc Gallant/Canadian Press))
You're out for a leisurely afternoon jog, plugged into your personal digital music device, unaware that something very dark and ominous is rapidly turning this nice sunny day into a summer tempest.

Storm's a coming and you're about to be caught in it.

By the time you realize what's happening, claps of thunder are drowning out your favourite tunes. You think you see a flash of lightning, so you rip off that headset and toss your personal digital music device as far as possible. After all, you've heard that they're dangerous in a storm because they attract lightning.

Lightning safety tips

  • When it roars, go indoors.
  • If you're outside, remove shoes that contain metal cleats.
  • If you're outside, it's safe to go into your car - but don't touch any metal parts.
  • If you're swimming, get out of the water immediately.
  • If you're indoors, stay away from windows and doors and stay away from anything that conducts electricity like landline telephones.
  • If you're outside, avoid being the tallest object anywhere or taking shelter near or under the tallest object, like a tree.
  • Do not stand near a fence.
  • If you're outside, do not seek shelter in a shed or any small open shelter on a sports field or golf course.

Not so, says Dr. Mary Ann Cooper of the University of Illinois. She's one of the world's leading authorities on lightning injuries.

"Nothing attracts lightning," Cooper told CBC News. "Metal does not attract lightning. The danger of using iPods and cellphones is that you're not paying attention to the weather."

Cooper says the message about thunderstorms and safety is simple: when it roars, go indoors.

Thunderstorms — and the lightning bolts that go with them — are common across most of the country through the summer months. It all has to do with moist, warm air coming north from the Gulf of Mexico colliding with cooler air masses coming down from the north.

"Lightning all begins in the clouds," said Kalin Mitchell of the CBC News weather centre. "We have many thousands of ice crystals. If there's enough movement of those crystals, they produce an electrical charge, much like the way rubbing a balloon against a piece of carpet builds up a static charge. When enough of an electrical charge is built up in that cloud, it's discharged either to another cloud or down to the ground."

Whatever that bolt hits when it makes contact with the ground is in for a real shock. A lightning bolt can carry up to 100 million volts of electricity — a million times more powerful than the current that runs through your house. The average flash of lightning could turn on a 100-watt light bulb for more than three months.

That's the bad news. The good news is that if you're hit, the vast majority of the electricity is carried around your body — not through it. You won't be fried.

The bad news is you could still be in for some pretty severe injuries.

"What happens is a nervous system injury where you have a brain injury with thought-processing and multi-tasking problems in the future," Cooper said. "You may have chronic pain because the nerves that are injured are constantly signalling the brain with pain, pain, pain from their injury."

Your chances of surviving a lightning strike are good. But you may find yourself so badly affected that you may not be able to return to your job, especially if it involved handling multiple tasks at the same time.

Besides injuries to the nervous system, you could also suffer eye damage, deafness or ringing in the ears, or amnesia.

Bolts can be deadly

Lightning strikes kill about seven Canadians a year and seriously injure another 60 to 70, according to Environment Canada which also estimates lightning flashes can be seen about 2.7 million times a year. The numbers are much higher in the United States, where more than 700 people are killed by lightning strikes. Florida is the most active state for lightning strikes. In Canada, the hotspot is Windsor, Ont.

Cooper says the best place to be when a storm is approaching is indoors, away from windows, landline telephones and plumbing.

"Lightning can strike outside and travel through your plumbing," Cooper said. "It's the same with hard-wired phones. Cellphones are OK."

But if you find yourself outside when that storm hits, there are precautions you can take. Your car is a safe place — not because it has rubber tires but because the metal body of the car conducts the electricity around the outside of the car. Yes, you can touch the steering wheel and still be safe. But hands off any metal that might be inside the car.

The average flash of lightning could provide enough power to light a 100-watt light bulb for more than three months. ((Dave Chidley/Canadian Press))
Other good places for shelter include substantial structures (keep away from windows). Never get closer than 30 metres to metal fences and take off shoes that have metal cleats.

Don't feel safe if you're standing outside wearing a pair of rubber boots, either.

"If lightning burns its way a mile through the air, do you think a little quarter-inch of rubber in your boots or tires will protect you? No, that's a myth," Cooper said.

Cooper also warns that you could be at risk well after the storm has passed. Lightning can strike up to 16 kilometres ahead or — or behind — a storm.

There is no way to predict where lightning will strike. You could be in a field surrounded by tall trees and you're the object that's struck. No single object attracts lightning. Lightning occurs on too large a scale to be influenced by small objects on the ground, including metal objects. The location of the thunderstorm overhead alone determines where lightning will hit the ground.

Some experts suggest following the 30/30 rule will help keep you safe when storms are in the area: seek shelter if the time between the flash of lightning and the clap of thunder is 30 seconds or less, and stay indoors for 30 minutes after the storm has passed.

Cooper says she doesn't advocate that rule anymore.

"The 30 seconds you spend counting is 30 seconds you could have been using to get to a safe place."