Search the Dictionary:

ozone layer
Courtesy Goddard Space Flight Center,

ozone layer:

The ozone layer, or ozonosphere, is a region of concentrated ozone in the outer stratosphere. It acts as the principal shield against dangerous ultraviolet radiation from the sun. The ozone layer was being damaged by the propellant gases in aerosol sprays and other chemicals released in certain kinds of manufacturing. Scientists said that the increase in ultraviolet rays reaching the earth would increase the occurrence of cancer and have other serious health consequences for people. An international treaty called the Montreal Protocol was passed in 1989 and was designed to protect the ozone layer by phasing out the substances that were harming the ozone layer. The ozone layer has improved since then but the problem will not be resolved totally for many years.