Aging of the skin produces changes in the glands that open through the pores onto the skin surface. Atrophy of these glands reduces the moisture that the skin retains in the dead and dying cells that form the outer layer of the skin. With a seasonal drop in humidity such as occurs in winter, dry skin worsens. The dry air of central heating systems adds to the problem of dry skin. Exposure outdoors to the wind and cold is an additional factor.
