Exposure to UV-B results in reddening of skin and sunburn. The risk of skin cancer grows with every sunburn. Staying in the shade does not provide complete protection from UV radiation. A considerable amount of UV does not come directly from the sun, but is scattered by the atmosphere. UV is scattered by the atmosphere stronger than visible light.
Physicians associate eye cataracts with UV exposure.
Sunburn is not connected with the sensation of heat. In fact, one can get serious sunburn in winter despite the feeling of cold. Snow, water, and concrete act like mirrors and significantly increase sunburning. Snow skiing enthusiasts should be particularly careful to protect their eyes and exposed skin since skiing generally is done at higher elevations with a high degree of reflection off the snow. Research indicates ozone holes, ozone depletion and seasonal changes can significantly affect the amount of UV exposure.