Depletion of the Ozone Layer
Ozone (O₃) is a naturally occurring molecule that contains three atoms of oxygen. The ozone layer is the region in the stratosphere about 20 to 35 km above the Earth’s surface which contains relatively high concentration of ozone. This layer is important because it absorbs most of the harmful ultraviolet radiation from the Sun and prevents the radiation from reaching the surface of the Earth. Overexposure of ultraviolet radiation causes skin cancer and cataract, lowers the body’s immune system and damages leaf cells.
However, the ozone layer is thinning. This is mainly due to the increasing levels of chlorofluorocarbons (CFCs) in the atmosphere. CFCs are used as coolants in air-conditioners and refrigerators, propellants in aerosol cans and foaming agents in the making of Styrofoam packaging. Once in the atmosphere, CFCs are broken down by ultraviolet radiation and the highly active chloride radicals are released. There radicals break down the ozone molecules in a chain reaction, depleting the ozone layer