The<unk> , or UV<unk> , is an international standard measurement of the strength of the sunburn-producing<unk>  (UV) radiation at a particular place and time. It is primarily used in daily forecasts aimed at the general public, and is increasingly available as an hourly forecast as well. The UV<unk>  is designed as an open-ended linear scale, directly proportional to the intensity of UV radiation that causes sunburn on human skin. For example, if a light-skinned individual (without sunscreen) begins to sunburn in 30 minutes at UV<unk>  6, then that individual should expect to sunburn in about 15 minutes at UV<unk>  12 – twice the UV, twice as fast. The purpose of the UV<unk>  is to help people effectively protect themselves from UV radiation, which has health benefits in moderation but<unk> cess causes sunburn, skin aging, DNA damage, skin cancer, immunosuppression, and eye damage, such as cataracts (see the section Human health-related effects of<unk>  radiation). The scale was developed by Canadian scientists in 1992, and then adopted and standardized by the UN’s World Health Organization and World Meteorological Organization in 1994. Public health organizations recommend that people protect themselves (for example, by applying sunscreen to the skin and wearing a hat and sunglasses) if they spend substantial time outdoors when the UV<unk>  is 3 or higher; see the table below for more detailed recommendations. The recommendations given are for average adults with lightly tanned skin. Those with darker skin are more likely to withstand greater sun exposure, while extra precautions are needed for children, seniors, particularly fair-skinned adults, and those who have greater sun sensitivity for medical reasons or from UV exposure in previous days.
Ultraviolet index
Dermal equivalent
NC ratio
Color vision
Biochemistry
Titer
Eagle score
Killing Season