Article from January, 2013

lighting_strikes

One of the most frightening circumstances in the field occurs when your expedition is confronted with a sudden or inescapable violent storm. Naturally we all attempt to avoid such situations but sometimes these arise without warning when we are expose

One of the most powerful and spectacular natural phenomena is lightning which occurs when the electrical potential in the atmosphere exceeds the natural resistance of air. Different theories suggest that lightning is generated by collision of raindrops and particles or by downward convection of negative charges. Lightning strikes the earth somewhere about 100 times per second or about 8 million times a day. In the continental US, data from the National Lightning Detection Network estimates an annual average of 20 million flashes with the highest concentration in central Florida. Most lightning accidents occur outdoors but approximately one third or more occur indoors and 10% occur during transport in motor vehicles. According to the Centers for Disease Control and Prevention, there were 374 deaths by lightning strike between 1995 and 2000 in the US with 75% occurring in the South and Midwest and 25% work-related. Worldwide, approximately 24,000 people die each year from lightning strikes and mortality from lightning is highest in Africa. However lightning injury data is unreliable in most countries and likely underreported.

If caught in the open, stay off ridges and away from single trees, remove and stow all metal objects (iPods, carabiners, crampons, ski poles, etc.), and move quickly away from iron ladders and wire ropes. Lightning current can follow wet ropes. Do not stand near a tall object, you are in danger from current jumping or passing through the ground. Assume the crouch position if you note a visible glow or you feel a sensation of your hair standing on end.

Surprisingly, 70% of lightning strikes are not fatal likely because they last milliseconds and have minimal energy transfer to internal organs (Zafren et al., Resuscitation, 2005). However, 75% of survivors have some permanent damage such as ringing in the ears, seizures, and blindness. Persons who are stunned or lose consciousness without cardiopulmonary arrest are unlikely to die. The very short exposure time to extremely high voltage may cause injuries due to high temperatures and blast waves in addition to electrical energy. Injuries from lightning occur in various ways: direct strikes, contact from touching an object while struck, current jumping from a nearby struck object, current passing through the ground, and blast injuries. Fortunately direct strikes (which are usually fatal) occur in only about 5% of cases.

The most common injuries occur to the nervous system (80%) with short episodes of paralysis and burning or numbness common. Short-term loss of consciousness, coma, seizures, headache, and intracranial hemorrhage may occur immediately while delayed effects include muscle weakness and subtle cognitive impairment. Cardiac problems occur in nearly half of the victims and cardiac arrest occurs without physical damage in about 10% due to disruption of automatic heartbeat rhythm. Deafness from tympanic membrane rupture by the blast is also common after lighting strike and ear injuries often occur with telephone use. Severe muscular pain and urinary protein excretion secondary to muscle injury sufficient to cause kidney failure if untreated are also often described. Superficial burns have a distinctive pattern and severe burns are rare but can be noted at entry and exit points of the current.

Rescue of lightning victims can be hazardous so wait until the danger of further strikes has passed. The patient is not electrified, so begin treatment immediately. Treatment of lightning victims is based on the ABCs of resuscitation – airway, breathing, circulation. Because the heart can frequently restart, begin CPR and continue as long as possible because prognosis is very good if oxygenation is maintained. It is important to support the cervical spine because the explosion of the strike may have caused fractures. Pain medication and first aid for burns are appropriate if immediate evacuation is unavailable.

In reality, no place outside is really safe when a thunderstorm hits. Distance and proper shelter are your best protection. Here are some common myths about lightning.

Common Lightning Myths

Lightning never strikes the same place twice. In fact, lightning often strikes repeatedly in places prone to lightning (tall isolated objects). If you want to watch something disturbing, watch the video of a man being struck twice and walking away (Lightning strikes).
Lightning cannot strike if it is not raining or if there are no clouds. False….lightning often strikes 3 miles or more and can strike 10-15 miles from the storm.
Lie flat on the ground if trapped outside and there is risk of lightning strikes. False. Lying flat decreases your height but increases the chance of being hit by ground current. Best to assume a crouch position if you cannot find shelter.
Inside a house is safe. Partially true. You must avoid any contact with a conduction path to the outside….phones, appliances, plumbing, TV cable wires, metal doors or frames.
A car provides safety from strikes. Partially true, but not because of the rubber tires. The metal roof and sides conduct the current away from you so convertibles and open topped vehicles do not provide protection.
No questions please about whether rubber-soled sneakers provide safety!

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This article was published in The Explorers Journal

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THE EXPLORERS JOURNAL.
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