Dermatology Library

U

Ultraviolet Index:

The Ultraviolet (UV) Index provides important information to help you plan your outdoor activities and avoid over-exposure to the damaging rays of the sun. Developed by the National Weather Service (NWS) and the Environmental Protection Agency (EPA), the UV Index is issued daily as a national service. The UV Index is a forecast, of the amount of ultraviolet expected to reach the Earth's surface when the sun is highest in the sky. The higher the index, the faster UV radiation causes damage to the skin and eyes. The index depends on the elevation of the sun in the sky, the cloud cover, and amount of ozone. The Index predicts UV levels on a 0-10+ scale and is usually published in daily newspapers with the weather, or is a part of television weather reports. Always take precautions against over-exposure, and take special care when the UV Index predicts exposure levels of moderate to above (5-10+).

Ultraviolet radiation:

The "sunburn" and "suntan" wavelengths of solar radiation. Ultraviolet radiation is the skin-damaging spectrum of sunlight.

Unidentified Skin Parasite Infection (USPI):

Unidentified Skin Parasitic Infection (USPI) is a serious skin condition that affects millions of men, women and children worldwide. It occurs when an unnamed organism or life form lives, feeds and breeds, under the skin of a human host. This infection was first recorded in medical books, in the early part of this century. However, because the parasite appears to have so many different metamorphic features, many of which may resemble human hair, fabric or lint (for example) turn of the century physicians wrongly assumed their patients must have been suffering from a psychosomatic illness rather than a disease. Even today, almost 100 years later, many in the medical community fail to recognize Unidentified Skin Parasitic Infection as a serious disease.

Urticaria (hives):

Hives, or "wheals", are pale red swellings of skin that occur in groups on any part of the skin. Urticaria is the medical word for hives. Each hive lasts a few hours before fading without a trace. New areas may develop as old areas fade. They can vary in size from as small as a pencil eraser to as large as a dinner plate and may join together to form larger swellings. Hives usually are itchy, but may also burn or sting. Hives are formed by blood plasma leaking out of small blood vessels in the skin. This is caused by the release of a chemical called histamine. Histamine is released from cells called "mast cells" that lie along the blood vessels in the skin. Allergic reactions, chemicals in foods, or medications can cause histamine release. Sometimes it's impossible to find out why hives are forming. Hives are very common - 10-20 percent of the population will have at least one episode in their lifetime. Most episodes of hives disappear quickly in a few days to a few weeks. Occasionally, a person will continue to have hives for many years.