The danger of lightning injuries
Lightning injuries were once the second most common cause of storm-related death in the United States.
They've been overtaken by flash floods and tornadoes in recent years; global warming has caused both to rise astronomically.
However lightning is still a threat. Related injuries kill more people each year than hurricanes, volcanoes, and earthquakes combined.
Far more injuries and deaths occur in tropical and subtropical countries. Behind the increased risk in these countries are higher lightning density (lightning strikes/km2/year), lightning-unsafe housing and local cultural beliefs that may prevent adequate prevention and mitigation.
As an example, in some Caribbean and African nations, it is believed that anyone injured by lightning has been cursed. They are shunned, along with their family.
One study estimated total annual fatalities to be about 24,000 and annual injuries about 250,000 for the tropical and subtropical areas of the world.
For most thunderstorms, 70-90 per cent of lightning strikes are intra-cloud (or from cloud to cloud); 10 to 30 per cent of lightning can be cloud to ground, depending on the storm.
Lightning strikes the earth more than 100 times each second and 8 million times per day. Worldwide, approximately 50,000 thunderstorms occur each day, potentially causing forest fires, injury to animals and people, and/or damage to electrical and communication lines and devices, leading to millions of dollars in economical loss.
Everyone is a potential victim. The danger of lightning may not be apparent to an individual because lightning can strike ten miles or more away from the rain of a thunderstorm.
Three factors predispose to a lightning hit: height of an object, isolation, and “pointiness”, which is not a factor with people.
Although most injuries occur outdoors, a few people are injured indoors every year from contact injuries with plumbing or landline telephone — mediated strikes (see below).
Types of injuries
The most important features of lightning harm are cardiac and neurologic injuries. Injuries range from tiny static electricity — like exposures to Keraunoparalysis (a temporary paralysis after lightning injury that may last minutes to hours); vascular spasm in the heart and brain leading to heart attack or stroke; direct neurologic damage; memory/sleep disturbances; heart arrhythmias; and all the way to cardiorespiratory arrest. Because persons struck by lightning have a better chance of survival than persons who experience cardiopulmonary arrest from other causes, resuscitation of such victims must be instituted immediately. Ear and eye injuries have also been noted as frequent consequences of these events.
Lightning causes death in about 10 per cent of its victims. Some reports suggest as many as 74 per cent of survivors of a lightning strike experience permanent injury; other studies suggest a lower percentage.
Lightning versus common electrical injuries
Although lightning injury can be classified as a special case of electrical injuries, its physics are far more distinct and complex than man-made electricity.
Less than 5 per cent of lightning deaths are caused by direct strike; the other 95 per cent are caused as lightning first hits another object (example: tree, tower, ground), then side flashes to a nearby person or passes through the roots, ground, pipes, or wires, on its pathway to that person. Fewer than half of all survivors have any signs of skin burns, probably because the lightning energy is mitigated by these primary targets, and because lightning has too brief of a contact time with the skin to cause a substantial burn. All these features are very different from a man-made electrical injury.
The primary risk factor for lightning injury is failure to acknowledge that lightning poses a threat. No place outside is safe when thunderstorms are in the area.
Many people wait until rain begins before seeking shelter; this is often late because lightning can travel as far as 10 miles in any direction from the thunderstorm clouds.
While lightning can be seen hundreds of miles away, thunder usually cannot be heard more than a few miles away.
By the time one hears thunder, one is already in danger and should be seeking a safer structure or fully enclosed metal vehicle. In fact, being inside a car or truck is a safe place because electricity will flow along the outside of any metal structure that it hits, not because of the minuscule effect of rubber composite tyres.
Hard-wired telephones become the conduit for the lightning charge to enter or to escape from a structure (and from a person). Although the telephone system may be grounded adequately for electrical surge protection, lightning energy surge is much too fast and strong for typical grounding to be protective. This type of injury has decreased substantially now that wireless systems are more in use and that no lightning danger is inherent to cellular phones. The US National Oceanic and Atmospheric Administration has advice for all of us: “When thunder roars, go indoors!”
•Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women's Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients' care recognition awards. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. You should never delay seeking medical advice, disregard medical advice or discontinue treatment because of any information in this article.
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