Friday, June 26, 2015

Lightning Strike - A Life-Changing Experience

Being struck by lightning is a life-changing experience for most people, and not in a good way. If you are fortunate to not be killed (only about 10 percent of people struck by lightning are killed), the injuries you suffer with may be with you the rest of your life.

There are five ways you can be struck by lightning.

A direct strike occurs when the person, usually in an open area, becomes part of the main lightning discharge channel. A portion of the current moves along and over the skin, and a portion moves through the body.

A side flash occurs when the lightning strikes a taller object near the person (like a tree) and part of the current jumps from that object to the person.

A person may also be affected by a ground current. When lightning strikes a tall tree, for example, the charge travels down the object to the ground and then along the ground surface. Ground current can cover a large area and is the cause of most lightning casualties. The current enters the body at the point closest to the lightning strike (for example, your foot) and exits the body at a point farthest away from the strike (your other foot). The greater the distance between these two points the greater voltage difference. The voltage difference is what drives the electrical current through your body and causes injury or death. Ground current is often fatal to livestock because of their large size, i.e. there is a large voltage difference between their front legs and rear legs and current travels trough the entire body.

Turf damage caused by ground current from a lightning strike.
Photo credit:  AlGamaty on Reddit

Conduction of lightning through wires or other metal surfaces allows lightning to travel long distances. Fences, electrical lines, pipes, or other metal surfaces can provide a pathway for lightning. Most indoor lightning casualties are related to conduction. That is why it is important to stay off of a corded phone, and stay away from anything plugged into an electrical outlet, water faucets and showers, or windows and doors.

Streamers develop as the downward-moving leader approaches the ground. These are upward streamers, and usually only one of the upward streamers makes contact with the leader to provide the main channel for the return stroke. However, when the main channel discharges, so do all the other streamers in the area. If a person is part of one of these streamers, they could be killed or injured during the streamer discharge even though they are not part of the main discharge.

A more detailed description can be found on the NWS Lightning Safety web page.

While some lightning strikes result in death, the majority do not. However, disabilities from a lightning strike can be severe and long-term.

Most people can survive a lightning strike because much of the current dissipates over the skin (what is known as flashover)instead of entering the body. The electrical current is taking the path of least resistance, and can travel easier along the skin than it can within the body. When you hear about people who have had their shoes or clothes blown off it is because the flashover causes rapid heating of any moisture in the shoes or under the clothes (e.g. from sweat). The water vapor (steam) rapidly expands producing enough force to tear shoes or clothing from a person's body. This tends to occur with side flashes.

When lightning strikes your home it may damage your computer, television, and other electronics. When lightning strikes a person the primary injuries are to the body’s “electronics” – the nervous system and the brain. The most readily apparent effect may be cardiac arrest. Serious burns seldom occur. Most burns are caused by other objects (rainwater, sweat, metal coins and necklaces, etc.) being heated by the current passing through them and causing the burn rather than being caused by the lightning itself. The  90 percent of victims who are not killed by lightning exhibit various degrees of short and long-term disability.

Damage to the nervous system and the brain may not be readily apparent. Symptoms may include fatigue, intense headaches, inability to concentrate, inability to process information, personality changes, and others. Some symptoms may not manifest themselves until sometime after the incident.  Often conventional medical testing (imaging, lab tests, etc.) will not show any physical changes that can be attributed to the lightning strike. Neurocognitive or neuropsychological testing may be used to identify functional and cognitive deficiencies.

There is research being done on the injuries resulting from lightning. Dr. Mary Ann Cooper, M.D. at the University of Illinois at Chicago heads the Lightning Injury Research Program. Her article “Disability, not Death, is the Main Problem with Lightning Injury” contains more information on the effects of lightning injuries.

The behavioral and personality changes that may be experienced by lightning-strike survivors are often hard for family and friends to understand.  Lightning Strike & Electrical Shock Survivors International, Inc. is a non-profit support group formed by a lightning strike survivor in 1989. Its mission is to provide support for survivors, spouses, and other interested parties as well as to provide education on the prevention of lightning and electrical injuries.

"The Body Electric"  is an excellent article on the experiences of and injuries suffered by lightning strike survivors.

For more information on the medical aspects of lightning injuries, see Lightning Injuries.
John Jensenius, Jr., a Lightning Safety Specialist for the National Weather Service performed an analysis of 261 fatalities from lightning in the U.S. from 2006 through 2013. While many of us associate golfing with most lightning fatalities, that is in fact not the case. He found that fishermen account for the majority of deaths (30, vs. 8 for golf). Men accounted for 81 percent of all fatalities. Jensensius broke down the data into a number of categories, including age, sex, general type of activity (work, leisure), and specific activities within those categories. He found the two-thirds of those killed were involved in leisure activities.

From "A Detailed Analysis of Lightning Deaths in the United States from 2006 through 2013" by John Jensenius, Jr.

You can read the entire report (12 pages) here.

Next: Lightning Safety

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