The ozone layer is an essential part of the earth's upper atmosphere, between about 10 to 30 miles above Earth in the stratosphere. While it is also present at ground level, for purposes of this discussion, the focus will be on the upper atmosphere.
The ozone layer is vital to life on the Earth, as it blocks a certain percentage of the ultraviolent rays emitted by the Sun. During the 1970s, scientists began to discover that man-made chemicals used in many household cleaning and personal hygeine products that were released into the air were gradually depleting the ozone layers. More specifically, manufacturers of products like hair spray and furniture polish had switched from pump bottles to aerosal spray cans. This manufacturing process involved the use of chloroflurocarbon (CHC), a compound that contains a number of substances including carbon, hydrogen, and chlorine. Particularly damaging to the atmosphere was the use of CHC in the manufacture of refrigerants like Freon, the substance used for decades in automobile air conditioning systems. The continued mass use of CHCs was determined to be the leading cause of ozone depletion.
Ozone depletion was determined to be occuring primarily over the Antarctic region, the South Pole. It's effect, however, has been global, and is considered one of the leading causes of climate change, evident by the shrinkage of the polar ice caps. Because of the depletion of the ozone layer, far more of the Sun's ultraviolent rays penetrate the remaining atmosphere. In addition to, or by extension of, the warming of regions of the earth, scientists have concluded that severe weather patterns are becoming more intense, causing greater levels of destruction from hurricanes and tornadoes. Finally, the increase in ultraviolent rays -- or, to be more precise, ultraviolent radiation -- has been found to be a possible determining factor in increased incidences of skin cancer among humans.
In an effort at bringing the issue of ozone depletion under control, the United States Government began to strictly regulate its use. The international community addressed the problem with the 1987 signing of the Montreal Protocol, which mandated reductions in the use of CHCs by signatory governments. Similarly, in 1989, the European Union committed to eliminating the use of CHCs by the 21st Century.