The National Park Service expects 70 million visits to the country's 54 national parks this year, mostly in the summer months.
Whether people stay for a day hike or a week's worth of back-country exploring, the most common reason for cutting a visit short is an injury or other medical problem.
Being prepared for outdoor emergencies and knowing basic outdoor first aid can help reduce the chances of ruining a vacation. But it's also important to put the risks in perspective.
If you think of bears and snakes as the biggest risks to life and limb in a national park, you're not alone. But there are other potential dangers that warrant concern, wilderness experts say.
Bee stings, for instance.
Anaphylactic shock in the wake of a bee sting can kill quickly. Yet most people don't know they are allergic to bee venom until they are stung, says Dr. Eric Weiss, associate director of trauma and emergency medicine at Stanford University Medical Center and author of many outdoor medical guides, including "Wilderness 911," published this year by Mountaineers.
In any case, be prepared. Take along Benadryl (diphenhydramine), available over the counter, to lessen the effects of a mild allergic reaction. And get a prescription for epinephrine, sometimes sold in the form of a pen-like injector. If symptoms of anaphylactic shock--hives, wheezing, shortness of breath--appear, use the epinephrine followed by Benadryl and get the person to medical help immediately.
Honey bees leave behind the stinger and the venom sac. "The venom sac can continue to pump," Weiss says. "Grab it and yank it out." Then apply ice or cold water.
Or put on a paste of baking soda and water to neutralize the acidity of the bee venom. Apply vinegar or lemon juice to wasp venom, which is alkaline, Weiss advises.
To lessen the risk of being stung, avoid smelling like a flower, Weiss tells hikers and campers. That means using unscented deodorant, unscented (or no) hair spray and skin lotion; leave perfume and cologne at home.
Ticks are another danger because they can transmit Lyme disease and other infections. To discourage tick attacks, use insect repellent and wear long pants and long sleeves--but this advice is often ignored in the hot summer months, at least during the day. In that case, Weiss says, campers and hikers should check themselves and each other for ticks every four to six hours. He says ticks often stay on the skin for hours before feeding.
If a tick is found, flick it off or remove it gently with tweezers. Don't use a match or insect repellent to remove it.
Wear light-colored clothing in green, white, tan and khaki, colors that tend to be less attractive to insects than black and other dark colors, Weiss advises.
Poisonous plants such as poison oak, ivy and sumac can also inflict pain and suffering by causing an extremely itchy rash. Poison oak is most common west of the Rockies. Besides avoiding the plants, you can apply a barrier cream such as IvyBlock, available over the counter.
If you come into contact with poison oak, ivy or sumac, try to get the rash-causing oil off the skin as quickly as possible; within a half an hour is best, Weiss says. Use products such as Oak-N-Ivy Tecnu Skin Cleanser or take a cold, soapy shower.
Snakes are a big concern to some people, Weiss acknowledges, but the likelihood of dying from a snake bite in the wilderness is very remote. Still, it's a good idea to keep your distance from snakes, poisonous or not. How close is too close? "A snake can strike half its body distance," Weiss says. A 6-foot snake could lash out at least 3 feet.
To avoid snakes, walk on trails where you can see where you are going. At the campsite, look before digging into a woodpile, and collect wood before dark.
If you are bitten, getting medical care is the most important measure. Call the hospital to alert them to your arrival, Weiss says, because they probably will need to request the antivenin treatment. You don't have to kill the snake and take it along for identification, as many people think, Weiss says.
Do not suction out the poison with your mouth and do not make an incision, he adds. Use of a special venom extractor can help, but only within minutes after the bite. If possible, rinse the area with water to remove venom from the skin. Remove jewelry and rings so they won't get stuck when the bite area swells up.
To prevent bear attacks, keep food and trash tightly sealed so the bears can't pick up the smell and come foraging, says Tom Olliff, a ranger and biologist in Yellowstone National Park.
In Sequoia and Kings Canyon national parks, visitors are reminded not to leave food in the car because the black bears that populate those parks (and Yosemite) are adept at breaking in, says Ralph Moore, wilderness coordinator for Sequoia and Kings Canyon. Bear-resistant food storage boxes can be rented for $3 a day or purchased for $60.
Many women have heard that they should avoid bear habitats if they are menstruating. Weiss says there's no evidence to support that belief.
In a study reported in the Journal of Wildlife Management in 1991, black bears exposed to human menstrual odors were uninterested.
Healthy Traveler appears on the second and fourth Sundays of the month. Kathleen Doheny can be reached at email@example.com.