Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.See all posts »
Lightning Safety Awareness
This post relates information learned in a recent issue (Volume 22, Number 3, 2011) of the journal Wilderness & Environmental Medicine, published by the Wilderness Medical Society.
In an article entitled “Lightning Safety Awareness of Visitors in Three California National Parks” by Lori Weichenthal et al, the authors set out to assess the level of lightning safety awareness among visitors at three national parks in the Sierra Nevada Mountains of California.
Having recently enjoyed a wonderful trip to Yosemite National Park (one of the study sites) and gotten caught in a powerful thunderstorm replete with multiple lightning strikes and wind-driven sheets of rain and icy hail, this is timely for me and very important for anyone who spends time outdoors.
There were no surprises in the conclusions derived from this study, but the investigation reinforces the notion that we don’t recall all that we need to know, or may have never fully understood lightning safety in the first place.
For instance, while participants in the national parks knew that lightning is more likely to strike in the afternoon, they were not aware of the dangers of seeking shelter in a small cave or group huddling. Few people understood proper body position, and other than avoiding metal objects or isolated tall trees, the respondents had too many errors (in my opinion) with respect to advice such as avoiding water or thick groves of trees. The authors appropriately concluded that there exist many educational opportunities, which can take many forms, including trailhead awareness placards, park visitor pamphlets, public service announcements, and national park web site education portals.
Here is some information on lightning avoidance from the 5th edition of the book Medicine for the Outdoors:
1. Know the weather patterns for your area. Don’t travel in times of high thunderstorm risk. Avoid being outdoors during a thunderstorm. Carry a radio to monitor weather reports. Lightning can lash out from many miles in front of a storm cloud, in seemingly clear weather. If you calculate (see above) that a nearby lightning strike is within 3 miles (5 km) of your location, anticipate that the next strike will be in your immediate area. The “30-30 rule” specifies that if you see lightning and count less than 30 seconds before hearing thunder, seek shelter immediately. Since thunder is rarely heard from more than 10 miles away, if you hear thunder, it is best to curtail activities and seek shelter from lightning. Do not resume activities outdoors for at least 30 minutes after the lightning is seen and the last thunder heard.
2. If a storm enters your area, immediately seek shelter. Enter a hard-roofed auto or large building, if possible. Tents and convertible autos offer essentially no protection from lightning. Tent poles are lightning rods. Metal sheds are dangerous because of the risk of side splashes. Indoors, stay away from windows, open doors, fireplaces, and large metal fixtures. Inside a building, avoid plumbing fixtures, telephones, and other appliances attached by metal to the outside of the building.
3. Do not carry a lightning rod, such as a fishing pole or golf club. Avoid tall objects, such as ski lifts and power lines. Avoid being near boat masts or flagpoles. Do not seek refuge near power lines or tall metal structures. If you are in a boat, try to get out of the water. If you are swimming in the water, get out. Do not stand near a metal boat. Insulate yourself from ground current by crouching on a sleeping pad, backpack, or coiled rope.
4. Move off ridges and summits. Thunderstorms tend to occur in the afternoon, so attempt to summit early and be heading back down by noon. In the woods, avoid the tallest trees (stay at a distance from the tree that’s at least equal to the tree’s height) or hilltops. Shelter yourself in a stand of smaller trees. Avoid clearings—you become the tallest tree. Don’t stay at or near the top of a peak or ridge. Avoid cave entrances. In the open, crouch down or roll into a ball.
5. Stay in your car. If it is a convertible, huddle on the ground at least 50 yards (46 m) from the vehicle.
6. If you are part of a group of people, spread the group out so that everyone isn’t struck by a single discharge.
7. If your hair stands on end, you hear high-pitched or crackling noises, or see a blue halo (St. Elmo’s fire) around objects, there is electrical activity near you that precedes a lightning strike. If you can’t get away from the area immediately, crouch down on the balls of your feet and keep your head down. Don’t touch the ground with your hands.
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