Let's look at what we know about this subject and see what's being done to improve things. It has only been about 50 years since people started looking for chemicals that could he used to keep things cold. Just after World War II, scientists discovered a group of chemicals which seemed to be just what they were looking for. This group of chemicals has a long, technical name known as chlorofluorocarbons which we have shortened to CFCs. So next time you see or hear the letters CFCs, you'll know what they stand for.
Halons are another group of chemicals which are just as important.
They are used mainly for fire protection. Everything seemed fine for many years. Factories around the world produced refrigerators, air conditioning units and all types of insulation. Before we talk about what that has to do with CFCs and Halons, let's have a quick look at what the ozone layer is. The ozone layer is a layer of ozone gas which surrounds the Earth some 15 to 35 km above its surface.