Jennifer Wirth, age 70, of Wilton, Conn., for her question:

WHAT CAUSES PEOPLE TO PERSPIRE?

Sweat glands cover the entire surface of the body with larger glands concentrated in such areas as the armpits, on the palms of the hands and on the soles of the feet. The main job of the sweat glands is not to rid the body of waste materials, but rather to help the body lose heat. Sweating doesn't actually reduce body heat, but when the perspiration evaporates it has a cooling effect.

People perspire in both hot and cool weather. When it's cool, the small amount of sweat produced evaporates almost as soon as it is formed. This is called insensible perspiration. During hot weather or when a person is exercising, sweat glands increase their production and drops of water often form on the skin. This is called sensible perspiration.