JoAnn Vanaman, age 13, of Enid, Oklahoma, for her question:

Why does the skin peel after a sunburn?

The skin is a series of closely knit layers. There are living derma cells, with nerves and blood vessels, and a tissue thin surface layer of lifeless epidermis cells. These tissue thin surface cells are always flaking; away and being replaced by worn out cells from below. As a rule, we do not notice that the pale epidermis cells flake away. But the epidermis changes color after a mild suntan and the flaky cells become visible.

However, when the skin is exposed to the scorching summer sun for too long, the deeper derma layers are sunburned. These living cells strive to repair themselves, but the damage causes pain and perhaps blisters. The healing process takes time, and many of the cells are too damaged to repair. They become dry and lifeless and new cells are made to replace them. As the rebuilding goes on below, the top layers of destroyed and withered tissue peel away.