Lightning Safety in the Outdoors
by John Shannon
There are few weather events in the outdoors that startle a person more than a close-striking bolt of lightning along with the sound of thunder. In the United States, lightning is the second most common cause of weather-related deaths (flood-related deaths are number one) with an average of 62 deaths per year. It can strike up to ten miles away from a thunderstorm, roughly the distance you can hear thunder. More than one half of deaths occur after a thunderstorm has passed.
In the simplest terms, lightning is the result of the buildup and discharge of electrical energy during a thunderstorm. Because the air in a lightning strike is heated to 50,000 degrees Fahrenheit, a shock wave is produced resulting in thunder. The distance from a strike can be calculated by counting the seconds between seeing the flash and hearing the thunder. For every five seconds counted, the lightning is one mile away.
Lightning injuries affect 800 to 1000 persons per year. In lightning injury, cardiac arrest is the main cause of death, burns tend to be superficial, and injuries often are what one would expect of short-circuiting or overloading the body's electrical systems (ringing ears, blindness, confusion, memory loss, abnormal heartbeat, and abnormal blood pressure). Because victims in cardiopulmonary arrest might gain the greatest benefit from resuscitation efforts, they should receive immediate first aid (reverse triage). The good news is most victims survive a lightning strike with proper treatment, including CPR if necessary; however, long-lasting neurological effects are common. All victims of lightning strike should seek immediate medical care.
The principle safety guideline during lightning activity is the 30-30 rule. The first "30" represents 30 seconds. If the time between when you see the flash and hear the thunder is 30 seconds or less, the lightning is close enough to hit you. If you haven't already, seek shelter or safer terrain immediately. The second "30" stands for 30 minutes. After the last flash of lightning, wait 30 minutes before leaving your safe area or entering unsafe terrain. The time constraints of reaching a certain campsite may pose a challenge during outdoor activities. Be prepared and have alternate plans.
The safest location during lightning activity is inside a large enclosed building, and the second safest location is an enclosed, metal, hard-topped vehicle. If a safe location is not nearby, look for safer terrain so that you are not the tallest object. Safer terrain is below tree line and away from open areas such as peaks, ridges, and open spaces of land or water. Do not stand under a small group of tall trees, but get at least 200 feet below the tree line. If the tree line is too far away, look for a depression, ravine or valley. Cave entrances are not a safe location. Get away from metallic objects including trekking poles, backpacks, boats, and bikes. Take proper clothing to remain warm and dry, and take something insulated to put under your feet. After reaching safer terrain or at any time there is evidence of imminent lightning strike (sensation of hair "standing on end", crackling noises or a visible glow), assume the lightning safety position. To get into the lightning safety position, squat down (on a sleeping pad or life jacket if possible), put your feet together, position your head downward, and place your hands over your ears. If hiking in a group, spread out at least 15 feet apart so the lightning won't travel between you if someone is hit.
Additional measures should be taken for specific outdoor recreational activities during lightning activity. While hiking, plan to be off peaks by early afternoon, when thunderstorms are most likely to occur in mountainous regions. While paddling, get to the shoreline as soon as possible, take your rain gear and life jacket, and get 200 feet within the trees or away from the shoreline. If paddling in deep canyons, seek safe moorage and get away from your boat. Bottoms of canyons are rarely struck. While cycling, seek appropriate shelter or safer terrain and get away from your bike. More information can be found at www.lightningsafety.noaa.gov.