Hazards of outdoor activities

Any outdoor activity entails many risks, even if participants do not recklessly place themselves in harm's way. Even a simple accident may create a dangerous situation that requires survival skills. However, with the correct precautions, outdoor recreation can be enjoyable and safe.

General safety measures
Every hazard has its own safety measure, and every ailment a particular remedy. A standard precaution for all backcountry activities is carrying the "ten essentials", a collection of tools chosen for their utility in preventing or reacting to various emergencies.

The common practice of traveling in a group improves safety in all regards. If one person is injured, group members can administer first aid or seek help. A group can avoid poor decisions that a lone traveler might make. If an emergency occurs, a group can pool its muscle power, brain power, and body heat.

Another precaution is informing people outside of the hiking group of the itinerary and expected return time. (Expected hiking time can be estimated using Naismith's Rule.) A communication device, such as a cell phone or a satellite phone, may help in the case of an emergency. However cell phone coverage in wilderness areas is often quite poor.

Dangerous circumstances
Adventurers rarely get themselves hurt if they manage to avoid particularly dangerous situations.

Losing the way
Travelers may become lost either if a party cannot find its way, or if a traveler becomes separated from the party and cannot find it again. Lost hikers who cannot find their way to their destination on time may run out of food and water, or experience a change in weather, exacerbating the risk of hiking hazards. It's even easier to lose the way if trails do not exist.

If a group splits up into several subgroups moving at different speeds, one of the subgroups may take a wrong turn at a trail junction. A common custom to avoid this is for the leaders to stop at junctions and wait for the others. Keeping the group together is important in the wilderness, especially when visibility is blocked due to weather, rocks, or trees.

Carrying a map and compass and knowing how to use them will decrease the risk of getting lost. Likewise, a Global Positioning System may prove invaluable, as it can pinpoint a traveler's location, revealing his exact position on the globe and the direction to roads, services and cities. Most GPS devices can also be designed to mark their path on a map, making it easy to backtrack. Family Radio Service, General Mobile Radio Service, and amateur radios operating on the "2 meters" band may help maintain communication. Whistles, signal mirrors, and flashing lights are low-tech emergency signals.

Inclement weather
Blizzards, flash floods, fog, sandstorms, tornados, and other meteorological events may or may not be predictable, and may require immediate response for survival. Some may restrict visibility, as does nightfall, which may prevent further travel. Gusts of wind may physically knock a hiker or climber off a ledge or narrow trail. Lightning is a regular and serious threat in many regions.

Hazardous terrain
Backcountry avalanches are generally triggered by the immediate action of the party. Precautions include training, monitoring weather conditions to learn the history of the snow pack, digging hasty pits, modifying the route, passing one-by-one through dangerous areas, wearing avalanche beacons, and carrying avalanche probes and snow shovels. Other non-avalanche snow immersions can be similarly dangerous including tree wells and care should be taken in wooded backcountry areas following heavy snowfalls.

Other mass movements include icefalls, landslides, and rockfall. When choosing a campsite care must be taken to avoid those along with snags, dead trees called "widowmakers".


 * Slips may occur on:
 * Wet rocks or logs. Walking in streams, rivers, lakes, and other water is dangerous due to poor visibility, uneven surfaces, smooth and algae or moss-covered rocks, and the current of the stream. Rubber soles grip poorly on slime, compared to felt soles, crampons, or hob-nailed boots. Precautions include awareness of the danger, using hiking sticks, loosening packs straps to lower gravity and in case of being submerged, and crossing with other people linked arm to arm.
 * Loose material. Loose gravel or scree on top of smooth rock acts like ball bearings. Precautions include spotting the situation ahead, keeping knees bent and weight forward, using hiking sticks, and brushing aside the gravel where possible.
 * Ice


 * Drownings are especially likely when accompanied by head injuries, in very cold water, or in white water. Head injuries may render people unconscious. Cold water can sap energy quickly. White water may be so frothy that it is impossible to float, or even swim, to the surface.

Pre-existing medical conditions
Some medical conditions may be triggered or worsened by outdoor activity, particularly when it is sudden or strenuous. Examples include heart disease, asthma, diabetes, anemia, and allergies. Vertigo and neurological illnesses may have serious consequences on dangerous terrain.

Metabolic imbalances
Metabolic imbalances can affect general functioning and lead to other injuries.
 * Dehydration can rapidly incapacitate an adventurer, especially in warm weather. In conditions of low humidity, sweat evaporates so quickly that a person may not notice the water loss. Carrying and drinking an adequate amount of water helps avoid dehydration. Depending on conditions, two liters of water may be enough for a day hike, but under hot conditions (such as hiking the Grand Canyon in summer), one liter per hour may be required. Naturally occurring water is often unfit to drink (see Potability of backcountry water).
 * Sweating removes not only water, but also salt. This may result in a deficiency of sodium (hyponatremia).  Eating salty snacks together with drinking water helps to avoid this problem.
 * If deprived of food for several days, travelers may become malnourished. Malnutrition takes several weeks to kill a person, but because it impairs judgment, it can cause problems much sooner.  Low blood sugar may have a similar effect, especially for those with diabetes.  Carrying extra food will minimize risk to the hiker.
 * Hypothermia is a potentially fatal drop in core body temperature. It occurs most easily in cold weather and when wet. Wet or damp clothing (due to rain, sweat, stream crossings, etc.) can bring it on even in relatively warm air, particularly at high elevation, windy conditions, or at low humidity.  Even if hypothermia does not kill the victim directly it causes confusion, irrationality and impaired judgment, increasing the risk of other injuries. Sufficient clothing helps prevent hypothermia, but some materials (especially cotton) are discouraged for their ability to absorb and hold water.
 * Heat exhaustion, possibly developing into heatstroke, can occur in hot weather, particularly if one is dehydrated or dressed too warmly. The risk of heatstroke can be minimized by avoiding direct sun if the temperature is too high, and staying wet when possible.  This is a life-threatening condition: a victim must be cooled off and transported to a hospital immediately.
 * Altitude sickness results from climbing rapidly to elevations beyond 2,500 metres (approximately 8,000 feet). The process of acclimatization generally takes several days, but may be helped by drugs, such as Diamox. Acute mountain sickness or AMS may develop into high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), both of which are life threatening and require immediate transportation to a lower altitude.
 * Carbon monoxide poisoning may occur in tents, igloos, cabins, or trailers due to faulty or misused equipment. It may also occur near the exhausts of motorboats, where the CO concentrations can be high enough to be quickly fatal.

Topical injuries

 * Frostbite can occur when bare skin is exposed to very low temperatures. For very cold weather, clothing can be arranged to minimize the amount of exposed skin. Maintaining good circulation is very important. Frostbitten tissue should not be re-warmed in the field.
 * Sunburn, which may occur in hot or cold conditions, can be debilitating. In snowy conditions special care must be taken to protect areas affected by reflected sunlight. In hot conditions, all skin should be covered from direct sunlight. Some areas, like the back of the knees, back of the neck, back of the ears, and bottom of the nose, are often neglected when sunscreen is applied.
 * Snow blindness, a burning of the cornea, is caused by the intense ultraviolet solar radiation multiplied by sunlit snow.
 * Burns occur when dealing with camp stoves. Boiling pots are overturned, clogged fuel lines explode, hot metal is touched with bare skin. Burns are also caused by campfires, cookfires and bonfires.
 * Lacerations may be caused by careless use of knives, axes, or contact with sharp rocks or barbed wire. Tetanus and other infections can result.
 * Poisonous plants, such as poison ivy or stinging nettle (see list), cause rashes.
 * Plant thorns and animal quills can cause deep puncture wounds, and can be difficult to remove, often requiring pliers.

Animals
In many areas, adventurers may encounter large predatory animals such as bears, or cougars. These animals rarely seek out humans as food, but they will attack under some conditions. Some hazardous encounters occur when animals raid human property for food. Additionally, if travelers come upon an unsuspecting animal and surprise it, it may attack. Regularly making loud noise, such as by clapping or yelling, reduces the risk of surprising an animal. Some people use bear bells as noisemakers, but these are usually too quiet to be heard from far away. Any mammal infected with rabies may inflict fatal bites.

Venomous animals, including snakes, scorpions, spiders and bees, may cause harm either directly or through anaphylactic shock. Overall, the greatest danger is from insects, such as mosquitoes, ticks and fleas, which carry communicable diseases.

Internal injuries
Cumbersome backpacks increase the risk of missteps and falls, particularly on difficult terrain. Poor judgement on steep or slippery slopes can lead to injury. Carrying a backpack may make a traveler more cumbersome.
 * Ankle sprain is a common and debilitating injury. Proper hiking boots can help prevent it.
 * Foot blisters are caused by friction and irritation of the skin. Wet socks and poorly-fitting shoes precipitate the occurrence of blisters.  Two layers of socks (using liner socks) help prevent blisters, and moleskin can be applied to blister-prone areas as a treatment or preventive measure.
 * Back injury may result from packing too much or not having a proper backpack. A pack for backpacking should be bought from a recreational store, and as a rule of thumb, a person should carry no more than one third of their body weight.  Hiking poles may also reduce the likelihood of back injuries by spreading the load across multiple points. Care should be taken to lift and put on the pack with the least strain.

Digestive infections
Dysentery may be caused by poor hygiene in camp, and is also associated with travel.