A WAG bag (Waste Alleviation and Gelling bag) is a portable human-waste disposal kit used to pack out solid waste from areas where burying it in a cathole is not allowed or practical — such as high-use zones, alpine terrain, rivers, and deserts. It contains gelling/deodorizing powder that solidifies waste and neutralizes odor, plus a sealable double-bag system for carrying it out to a trash receptacle.
Giardia (Giardia lamblia) is a microscopic parasite found in untreated backcountry water (and spread via fecal contamination) that causes giardiasis, a gastrointestinal infection. After an incubation period of one to a few weeks, it can cause diarrhea, gas, bloating, cramps, nausea, and fatigue that may last for weeks. A leading reason hikers treat their water, giardia is prevented by purifying all drinking water and practicing good hygiene, and treated with prescription medication.
Sun protection is the set of measures used to guard against the sun's ultraviolet (UV) radiation, which causes sunburn, eye damage (including snow blindness), premature skin aging, and skin cancer. It's especially important outdoors because UV intensifies with altitude and reflects off snow and water, and it's one of the Ten Essentials. Protection combines sun-protective clothing (UPF), sunscreen, lip balm with SPF, a brimmed hat, and UV-blocking sunglasses.
A blister is a fluid-filled pocket that forms between layers of skin in response to repeated friction, often worsened by heat and moisture. The most common hiking and running ailment, blisters typically form on the feet and can be trip-ending if neglected. They are largely preventable by addressing 'hot spots' early, and treatable in the field with proper cleaning, draining (if needed), and protective dressing.
Snow blindness (photokeratitis) is a painful, temporary condition caused by overexposure of the eyes to ultraviolet (UV) light — essentially a sunburn of the cornea — most often from intense UV reflected off snow, ice, or at high altitude. Symptoms (pain, gritty feeling, watering, redness, light sensitivity, and blurred or lost vision) typically appear hours after exposure and resolve over a day or two. Snow blindness is preventable with proper UV-protective eyewear, and is a real hazard in snowy, high, or bright environments.
Hyponatremia is a condition of abnormally low sodium concentration in the blood, which in endurance sports is most often caused by drinking excessive amounts of water (and other low-sodium fluids) without replacing the sodium lost in sweat, diluting the body's sodium. Symptoms range from nausea, headache, bloating, and confusion to, in severe cases, seizures and life-threatening brain swelling. Often confused with dehydration, hyponatremia is essentially the opposite problem, and is prevented by sensible, not excessive, drinking plus electrolyte replacement.
Dehydration is a condition in which the body loses more fluid than it takes in, leaving it without enough water to function properly — common in the outdoors through sweating, exertion, heat, altitude, and inadequate drinking. Symptoms range from thirst, dark urine, dry mouth, headache, and fatigue to dizziness and worse as it progresses. Dehydration impairs physical and mental performance, increases the risk of heat illness, and in severe cases becomes dangerous, making consistent hydration a basic safety practice.
Heat stroke is the most severe, life-threatening heat illness, in which the body's temperature rises dangerously high (often around 40°C/104°F or above) and its cooling mechanisms fail, leading to altered mental status — confusion, agitation, slurred speech, or loss of consciousness. A medical emergency that can rapidly cause organ damage and death, heat stroke requires immediate aggressive cooling and emergency medical evacuation. The hallmark warning sign is a change in mental state in someone who is overheating.
Heat exhaustion is a heat-related illness caused by the body overheating, typically with significant loss of water and salt through heavy sweating, and is marked by symptoms such as heavy sweating, weakness, dizziness, nausea, headache, and cool, clammy, pale skin. A serious warning sign that the body is struggling to cope with heat, heat exhaustion requires prompt cooling, rest, and rehydration — and if untreated, it can progress to life-threatening heat stroke.
Hyperthermia is an abnormally high body temperature caused when the body absorbs or generates more heat than it can shed — the opposite of hypothermia. It describes a spectrum of heat illness from heat cramps and heat exhaustion up to life-threatening heat stroke. On the trail it results from heat, humidity, exertion, dehydration, and inadequate cooling.
