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Exposure
Category |
UV Index
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Sun Protection Recommendations
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LOW
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<2
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Wear sunglasses on bright days. In winter, reflection off snow can nearly double UV strength. If you burn easily, cover up and use sunscreen. |
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MODERATE
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3-5
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Take precautions, such as covering up and using sunscreen, if you will be outside. Stay in shade near midday when the sun is strongest. |
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HIGH
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6-7
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Protection against sunburn is needed. Reduce time in the sun between 11 a.m. and 4 p.m. Cover up, wear a hat and sunglasses, and use sunscreen. |
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VERY
HIGH
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8-10
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Take extra precautions. Unprotected skin will be damaged and can burn quickly. Try to avoid the sun between 11 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and sunglasses, and use sunscreen. |
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EXTREME
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11+
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Take all precautions. Unprotected skin can burn in minutes. Beachgoers should know that white sand and other bright surfaces reflect UV and will increase UV exposure. Avoid the sun between 11 a.m. and 4 p.m. Seek shade, cover up, wear a hat and sunglasses, and use sunscreen. |
The presence of an upper layer of atmospheric ozone shields the earth's surface from incoming solar ultraviolet radiation and protects us from its effects. Many epidemiological studies have recognized that UV radiation is harmful to animals and plants. The UV rays have been linked to skin cancer, cataracts, and probably macular degeneration an important cause of blindness in America. There are 2 types of UV radiation: A and B, both are dangerous. UV-A is in the 320 - 400 nanometers band, and UV-B is in the 290-320 nanometers band action spectra. UV-B in sunlight is the most biologically significant wavelength. The measure of outdoor UV exposure is difficult. The fraction of UV-A and UV-B is constantly changing due to solar elevation, angle, varying hourly and seasonally and also varies with the ozone level. Sunburn is the result of overexposure to the sun's ultraviolet radiation. Long-term cumulative sun exposure increases the risk of melanoma and non-melanoma skin cancer. Melanoma is a kind of skin cancer, sometimes called malignant melanoma. It arises from the melanocytes, the cells where pigment is synthesized. This is a very serious kind of skin cancer that can cause death. If melanoma is caught early, when still very small, it can be cured. Melanoma can have many different shapes and appearances and can occur any place on the body.
Non-melanoma skin cancers are: Basal cell cancers and squamous cell cancers. Basal cells are usually seen in exposed areas of the body, they are slow growing and rarely spread internally. Squamous cells also appear in sun exposed areas, but is more aggressive than Basal cell. About 3% of them spread to distant parts of the body. Both cancers are more prevalent in men due to greater sun exposure.
Prevention:
Sun Sensitivity
Some people experience a skin reaction to the sun rays after even a brief sun exposure. The skin will be red, itchy, or swollen or will blister. These individuals are called photosensitive or "sun sensitive". The skin reaction will last longer than sunburn and be more painful. It is important to check with your physician about medications that can make your skin more sensitive to sun exposure.
The best known products to cause increased sensitivity are:
Beneficial Effects of UV Radiation
UV Radiation is beneficial in vitamin D formation. Vitamin D deficiency can be corrected by sunlight exposure. Also, sunlight is beneficial in Seasonal Affective Disorder.
