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Lightning Strikes: How to Lower Your Risk

Michael Cherington, MD; Philip R. Yarnell, MD with James R. Wappes


Lightning strikes claim the lives of about 100 people each year, and even more people are injured. You can take several steps to lower your risks. Whether you're at home, on the golf course or ball field, or hiking in the mountains, prevention is a matter of lightning smarts.

Staying Alert

No matter what your activity, you need to keep an eye and an ear to the sky when outside. Be alert for darkening skies, flashes of light, or thunder. A sudden drop in temperature and increase in wind often signal an impending lightning storm.

Know the flash-to-bang system of measuring lightning distance. Because light travels much faster than sound, the time between a lightning bolt and thunderclap will tell you how far away the lightning is. Each 5-second count equals 1 mile. Before the count reaches 15 seconds or less (3 miles or closer), head inside or take other precautions (table 1).

Table 1. Steps to Take to Avoid a Lightning Strike

Step Reason
  • Know the flash-to-bang system to gauge how far away storm is
Every 5 seconds between the flash of lightning and the sound of thunder equals 1 mile
  • Remain in safe shelter or closed automobile
Current travels over the outside of cars
  • Get off mountain peak by 11:00 am
  • Plan outdoor activities when storms are infrequent
Most lightning strikes happen between 11:00 am and 9:00 pm
  • Avoid standing under an isolated tree
  • Avoid high terrain and open fields
  • Descend below timberline
  • If caught in an open field, seek a low spot and crouch in a curled position with feet together
Lightning targets are usually the tallest objects in the area
  • Get out of lakes, rivers, and swimming pools
Water is an excellent conductor of electricity
  • Stay away from metal objects like golf clubs, fences, and bicycles
Metal objects are preferred conductors of electricity
  • Beware of danger at onset and end of storm; don't resume outdoor activity prematurely
Many lightning strikes occur before and after peak flash activity

If you feel an electric charge, the hair on your head or body standing on end, or your skin tingling, a lightning strike may be imminent. If a safe haven is not available and you are caught in an open field, immediately squat like a baseball catcher. Crouch down on the balls of your feet and bend forward so that your head is low but no other part of your body touches the ground. Keep your feet together to minimize body contact with the ground, which minimizes the risk of being hit.

Outside Chances

Lightning typically strikes the tallest object in the area. That's why mountaintops, open fields, and lakes—sites where you are likely to be the tallest object—are the most dangerous places in a storm.

One of the safer havens is the inside of an automobile (not a convertible) with its doors and windows closed. One of the most dangerous places is just outside a car, van, or truck, because electric current travels around the outside of vehicles.

Modern buildings with steel girders or houses provide good protection, too. Such structures are usually grounded, meaning that the electricity from a lightning bolt will tend to bypass the inside of the building without harming the occupants. Beware that some structures, including tents and sheds (with or without metal roofs) may not be grounded.

In the mountains. Climbers and hikers should be below timberline by 11:00 am. Otherwise, they may face exposure during a storm when they have fewer options (see "Rocky Mountain Skies," below).

Rocky Mountain Skies

The Rocky Mountains attract millions of visitors each year, and, unfortunately, some of these visitors are hit by lightning. The Lightning Data Center in Denver has accumulated data from lightning strikes in the region that give insights about those who are struck.

Lightning-related injuries in the Rockies usually affect healthy people who are engaged in recreation or sports. More than half of those who died of lightning strikes in the Rockies were visitors. Being hit above timberline is often fatal.

Male victims outnumber female victims four to one. The typical casualty is a healthy man in his mid-30s. Most injuries occur in the summer months between 11:00 am and 9:00 pm. High on the list of activities are mountain hiking, climbing, camping, fishing, boating, and golfing.

Some of these injuries and deaths are preventable. Many vacationers are unaware of the measures they can take to lower their risk of being struck. They should educate themselves about lightning strikes. They should be near safe shelter and try to avoid high terrain, golf courses, and bodies of water during high lightning activity (late morning to evening).

If you are caught above the tree line when a storm approaches, descend quickly. Avoid isolated trees. It is better to run into a forest.

Electric storms can also develop in the middle of the night. To lower your odds, don't pitch your tent near the tallest trees in the vicinity.

In open areas. Hikers, golfers, and others should run into a forest if a shelter or car is not nearby. Drop metal objects like golf clubs, tennis rackets, umbrellas, and packs with internal or external metal frames.

Get off golf carts, tractors (including lawn tractors), motorcycles, bicycles, and horses. Metal bleachers at sports events, metal fences, and utility poles are also to be avoided.

If you are caught in an open field, seek a low spot. Crouch with your feet together and head low.

If Someone Is Struck

People who have been hit by lightning carry no electric charge and can be safely tended to. Also, victims who appear dead can often be revived. If it's an option, call 911 for help. If the person is not breathing, begin mouth-to-mouth resuscitation. But if a pulse is absent as well and you know cardiopulmonary resuscitation (CPR), begin CPR. Stay with the victim until help arrives.

Don't sit or lie down, because these positions provide much more contact with the ground, providing a wider path for lightning to follow. If you are with a group and the threat of lightning is high, spread out at least 15 feet apart to minimize the chance of everybody getting hit (see "If Someone Is Struck").

Don't return to an open area too soon. People have been struck by lightning near the end of a storm, which is still a dangerous time.

On the water. Swimmers, anglers, and boaters should get off lakes or rivers and seek shelter when storms approach. Drop any fishing rods. Boaters who cannot get off the water before the storm hits should crouch low. Once on land, get at least 100 yards away from shore.

For further information or medical references on lightning safety, write the Lightning Data Center, St Anthony Hospital, 4231 W 16th Ave, Denver, CO 80204.

Remember: This information is not intended as a substitute for medical treatment. If you have a health-related concern, consult a physician. Also, the tips discussed here may lower injury risk, but the unpredictability of lightning affords no guarantees.

Dr Cherington is a clinical professor of neurology at the University of Colorado School of Medicine in Denver and is founder and chairman of the Lightning Data Center at St Anthony Hospital in Denver. Dr Yarnell also is a clinical professor of neurology at the University of Colorado School of Medicine and a member of the Lightning Data Center. James R. Wappes is a senior editor of The Physician and Sportsmedicine.




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