I’ve met a few people who have been struck by lightning and lived to tell about it, and I thought I’d pass along some information about lightning injuries and how to prevent them. Much of this information comes a recent class in Advanced Wilderness Life Support (AWLS)
Interesting facts about lighting:
• Lightning strikes are the second leading environmental cause of death (behind flash floods) in the United States, with an average of 50-300 deaths per year.
• There are 3-5x as many people who are struck by lightning and survive than die.
• Nationally, there are 20 million cloud-to-ground flashes detected annually. In some summer afternoons, more than 50,000 flashes per hour are detected.
• The most common months of injury are June, July and August, although lightning strikes may occur during any time of year (even in snowstorms).
• The most common time of day for deaths due to lightning strikes is in the afternoon between 3pm and 6pm local time and this is because of the sun heating the ground which causes vertical cumulus clouds to form that may be tall enough to produce lightning.
• Florida is the worst state for lightning deaths with nearly 2x as many deaths than the next state.
• The most dangerous times for a severe lightning strike are before the storm appears and after it has passed.
• Lightning may travel nearly horizontally as far as 10 miles in front of a thunderstorm and seem to occur out of a “clear blue sky,” or at least when it is sunny.
• Lightning does commonly strike twice in the same place.
• A lightning bolt is a unidirectional massive current impulse carrying up to 30 million volts.
• A lighting bolt is about 6-10cm in diameter, but the ionized sheath is much broader (up to 20cm). The temperature of the sheath is usually around 8,000 degrees centigrade.
• There is no need to be concerned about getting shocked or injured by rescuing a person who has been struck by lightning because lighting does not leave a residual charge on a victim.
• Contrary to popular myth and what is seen in cartoons, deep burns are unusual after lightning injury. At the most, some minor second-degree burns may occur from superheated metal objects.
Mechanisms of injury: People can be injured by lightning in several ways:
1) Direct strike: a person is hit directly by a bolt of lightning and this happens most commonly with people who are caught in the open and unable to find cover. This is the deadliest type of strike.
2) Side splash: lightning directly strikes another object such as a tree or building, but the current flow, which seeks the path of least resistance, jumps from its original pathway onto the victim. This is the most common cause of lighting injury. Side splashes may also splash indoors from metal objects such as plumbing or telephones and may even occur from person to person when several people are standing close together.
3) Contact exposure: occurs when a person is holding onto or touching an object that is either directly hit or splashed by lightning. The current passes through the object onto the victim.
4) Ground current or step voltage: lightning strikes the ground or a nearby object and the current spreads through the ground. If a person has one foot closer to the strike than the other foot, an electrical potential difference between the two feet may occur and the current may pass up one leg and down the other leg. This is a common mechanism for several people being injured at the same time.
5) Blunt trauma: injury due to the impact of the concussive force of the strike itself or from being thrown due to the extreme nature of the muscular contraction from the electrical charge.
How lightning affects the body: injuries occur from a “short circuiting” of several of the body’s electrical systems as well as the more direct trauma and indirect trauma due to the muscular contraction and being thrown. The most common cause of death in a lighting strike victim is cardiopulmonary arrest.
Treatment: I think it’s important for everyone to be trained in CPR. In lightning victims, we usually perform reverse triage and initiate CPR on those patients who are pulseless and apneic (not breathing) before caring for those who have spontaneous signs of life. This is because those with no spontaneous breathing or heartbeat may recover and will require assisted breathing until their respiratory drive returns. Assisted breathing for these patients may prevent a secondary cardiac arrest due to low oxygen intake. If a victim does not regain a pulse within 20-30 minutes we usually then discontinue the resuscitation. The patient will need evacuation to the nearest medical facility even if the individual does not have any overt evidence of damage. There is a high likelihood of some sort of injury that is not served best by staying in the outdoors. Splinting fracture and spinal precautions is necessary.
Avoiding lightning injuries:
1) 30-30 Rule: The first “30” is when the time between seeing the lightning and hearing the thunder is 30 seconds or less, then people are in danger and should be seeking appropriate cover. The second “30”: outdoor activities should not be resumed until 30 minutes after the last lightning is seen or last thunder is heard.
2) Seek shelter in a substantial building or in an all metal vehicle: small shelters such as golf, bus and rain shelters may increase a person’s risk of being struck due to side splash as the lightning flows over the building. All metal vehicles are safe because the metal will diffuse the current around the occupants to the ground. A convertible is not a safe alternative. It is a myth that rubber tires provide insulation.
3) If you are caught in a storm outside without a safe building or vehicle: Stay away from metal objects and those items that are taller than you.
4) Avoid areas near power lines, pipelines, ski lifts, and other large steel objects.
5) Do not stand near or under tall isolated trees, hilltops, or at a lookout or other exposed area.
6) In a forest, seek a low area under a growth of saplings or small trees. Seeking a clearing free of trees makes a person the tallest object in the clearing.
7) If you are completely in the open, stay far away from single trees to avoid lightning splashes and ground current.
8) If you are on the water, seek the shore and avoid being the tallest object near a large body of water.
9) If indoors, avoid open doors, windows, fireplaces and metal objects such as sinks and plugged in electrical appliances. Do not talk on the telephone, as the telephone lines are not usually grounded like electrical wires.
References: Advanced Wilderness Life Support Handbook
This document is for informational purposes only, and should not be considered medical advice for any individual patient. If you have questions please contact your medical provider.
I hope that you have found this information useful. Wishing you the best of health,
Scott Rennie, DO