The ozone layer is located in the stratosphere several miles above the Earth's surface. Ozone is a very important atmospheric gas. As electromagnetic energy travels from the sun through space, it enters the Earth's atmosphere. One of those electromagnetic waves is called ultraviolet light. Ultraviolet light energy gets absorbed by the ozone layer keeping much of those harmful rays away from the organisms on Earth. However, due to the use of chemicals such as chloroflurocarbons or c.f.c.'s in aerosol spray cans and as refrigerants, a hole in the ozone layer formed and was seen back in the 1970's. This is because these chemicals reacted with the ozone and caused a hole to form in the ozone layer. Many countries have stopped using c.f.c.'s and it is estimated that the hole in the ozone layer should eventually close. However, higher levels of ultraviolet light have been linked to skin cancer and the number of cases of skin cancer have been steadily increasing.