ozone layer

Definition

Belt of ozone gas 15 to 50 kilometers above the earth's surface where ozone is present in concentrations of a few parts per million. This layer blocks (absorbs) ultraviolet part of the solar radiation (which causes skin cancer) from reaching the earth's surface. Ozone depleting substances thin this layer resulting in large areas (called ozone Holes) having half or less ozone than normal to appear. In 1985, the UK researchers in Antarctica discovered thinning of ozone layer has been occurring since 1979. By 1988 it was established that the layer was thinning fast over the entire globe. Also called ozone shield.