In the 1980s, scientists began accu-mulating evidence that the ozone layer was being depleted. Depletion of the ozone layer results in increased UV radiation reaching the Earth's surface, which in turn can lead to a greater chance of overexposure to UV radiation and the related health effects of skin cancer, cataracts, and immune suppression.
Ozone is a naturally occurring gas that is found in two layers of the atmosphere.
In the layer surrounding the Earth's surface the troposphere ground-level or bad ozone is an air pollutant that is a key ingredient of urban smog. The tro-posphere extends up to the stratosphere, which is where good ozone protects life on Earth by absorbing some of the sun's UV rays. Stratospheric ozone is most concentrated between 6 to 30 miles above the Earth's surface. Strong winds carry CFCs into the stratosphere in a process that can take as long as 2 to 5 years. When CFCs break down in the stratosphere, they release chlorine, which attacks ozone.