The Sun's Dark Side

For all its beneficence, the sun is not too kind to those who, intentionally or not, overexpose themselves to its warming rays. While most of the harmful solar radiation is absorbed by the ozone layer, enough ultraviolet light gets through the atmosphere to endanger the unwary.

In addition to the occasional painful sunburn, long-term exposure to the sun, especially between 10 a.m. and 3 p.m., weakens the skin's elasticity and brings on premature wrinkling and sagging. Of greater concern, it causes as many as half a million new cases of skin cancer every year. Most of these are basal or squamous cell carcinomas, which have high cure rates. But solar radiation may be a cause of melanoma, which can be fatal. Ultraviolet light apparently weakens the immune system; after a severe sunburn, some people suffer outbreaks of oral herpes or other disorders. Excessive exposure aggravates cases of chicken pox and can be especially dangerous, even fatal, to victims of lupus.

Sunscreens with a skin protection factor SPF of 15 or higher can minimize the risks to skin and the immune system. People who have allergic reactions to ) the sun, in the form of hives, blisters, red blotchy areas or bumps, may be using some drug, cosmetic or perfume that makes them more sensitive to sunlight. Avoiding such products will generally help solve the problem.

Ultraviolet rays have been implicated in the development of cataracts, a clouding of the eye lens. The rays chemically alter the lens' proteins, making them stick together and turning a clear lens murky. For protection during long exposure to the sun, doctors recommend wearing sunglasses, especially those that completely block ultraviolet, and wide-brimmed hats.