Exposure to ultraviolet (UV) radiation is a major risk factor for most skin cancers. Sunlight is the main source of UV rays. Tanning lamps and beds are also sources of UV rays. People who get a lot of UV exposure from these sources are at greater risk for skin cancer.V rays damage the DNA of skin cells. Skin cancers start when this damage affects the DNA of genes that control skin cell growth. There are 3 main types of UV rays: 1  UVA rays age skin cells and can damage their DNA.
Northern Africa. The Sahara is the largest desert in the world and occupies approximately 10 percent of the African Continent. The ecoregion includes the hyper-arid central portion of the Sahara where rainfall is minimal and sporadic. Although species richness and endemism are low, some highly adapted species do survive with notable adaptations.
The terrain of Southern Africa is varied, ranging from forest and grasslands to deserts. The region has Kek low-lying coastal areas, and mountains. In terms of natural resources, the region has the world's largest resources of platinum and the platinum group elements, chromium, vanadium, and cobalt, as well as uranium, gold, titanium, iron and diamonds.