ultraviolet light

People who exercise out of doors may be exposed to ultraviolet (UV) light for long periods and are at particular risk from its damaging effects. UV light can penetrate the skin and burn underlying tissues. Certain wavelengths disrupt normal cell activity and are linked with the development of skin cancers (e.g. melanoma). There are a number of sensible precautions that participants in outdoor activities should take:

• wear a hat or cap to shade the head and back of the neck, particularly for long-duration activities such as 18 holes of golf or a marathon
• keep your arms, torso, and, if possible, legs covered with pale-coloured clothing to reflect the light
• apply a suitable barrier on exposed parts of the body (see sun-protection factor)
• wear sunglasses which protect the eyes from damaging UV rays; this is especially important at high altitudes where UV light is especially intense
• exercise outdoors when the UV light is less intense, before 10 a.m. and after 4 p.m.
• seek medical advice if any persistent sores develop or if moles change appearance.

Light beyond the range of human vision, at the short end of the spectrum. It occurs naturally in sunlight; it burns and tans the skin and converts precursors in the skin to vitamin D. It is used in the treatment of psoriasis and other skin conditions. Prolonged or excessive exposure to ultraviolet light can damage the skin and increase the susceptibility of the skin to cancer.

Electromagnetic radiation with short wave-lengths and lying outside the visible spectrum of light. Sunlight contains ultraviolet light which causes sunburn.