A blanket of ozone high above Earth's surface is critical for life, absorbing harmful ultraviolet radiation from the Sun that would otherwise damage cells of both plants and animals. This "stratospheric ozone layer," which resides between approximately 10 and 50 kilometers (6 and 30 miles) high, can be destroyed by some human-made gases – chlorofluorocarbons (CFCs), for example.
CSL scientists have led international efforts to understand the chemical and related processes that lead to ozone depletion and ozone recovery. Results from more than two decades of laboratory work, field research, and computer modeling help scientists clarify the effects of people's actions (the use of ozone-depleting chemicals in spray cans and air conditioners, for example) and policies (restrictions in the production of certain chemicals) on Earth's protective stratospheric ozone layer.
Today, the Montreal Protocol on Substances that Deplete the Ozone Layer (updated many times since its original passage in 1987) incorporates many of CSL's scientific findings. In support of the Montreal Protocol, CSL researchers work with international colleagues, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to periodically update governments on the latest scientific understanding of the ozone layer. The quadrennial report, Scientific Assessment of Ozone Depletion, compiled from the work of hundreds of researchers representing dozens of countries and subjected to a formal review process, is coordinated and prepared at CSL prior to publication under the auspices of the WMO and UNEP.