Almost 60,000 people worldwide die from skin cancers each year caused by too much sun, estimates the World Health Organization, in its report on the global health consequences of overexposure to the sun's ultraviolet rays.

It is impossible -- and undesirable -- to avoid UV radiation altogether. The sun's ultraviolet rays enable the production of vitamin D in the human body and provide other health benefits.

But too much UV radiation can lead to skin cancer, sunburn, weathering of the skin, cold sores and cataracts. It directly contributes to the deaths of as many as 60,000 a year, according to the WHO report "Solar Ultraviolet Radiation."

Unseen and Unfelt

Malignant melanoma, a severe cancer with a low survival rate, causes approximately 48,000 of these deaths. The other 12,000 are caused by other forms of skin cancer, such as squamous cell carcinoma and basal cell carcinoma.

Squamous cell carcinoma usually progresses less rapidly than melanoma and is less likely to cause death or ongoing disability. Basal cell carcinoma occurs primarily in the elderly.

UV rays are invisible. They don't cause the warm sensation many associate with sunbathing, but they are present nonetheless. When the sun is high in the sky, typically between 10 a.m. and 2 p.m., UV radiation is most intense. People who live at high altitudes or near the equator -- where the sun's rays are more direct -- are subject to more UV radiation risk.

One's immediate surroundings also contribute to the level of radiation exposure. For example, fresh snow reflects as much as 80 percent of UV rays, while water and soil reflect less than 10 percent. Beach sand reflects about 15 percent of UV rays.

Don't Get Burned

WHO's report recommends using sunscreen with an SPF of 15 or higher, choosing shady spots over sunny locations outdoors, and never going to tanning salons.

"We all need some sun," says Dr. Marie Neira, WHO director for public health and the environment, "but too much sun can be dangerous -- and even deadly. Fortunately, diseases from UV. . .are almost entirely preventable through simple protective measures."

Common sense goes a long way toward achieving a healthy level of sun exposure. Sunshine spilling into the house through windows and doors -- along with plenty of fresh air -- is a good thing. Taking a walk on the beach -- with the use of sunscreen, sunglasses and a hat -- is healthy as well as enjoyable.

The point is to take sun in small, sensible doses, and to avoid getting burned.