Ozone depletion is a term used to describe two related phenomena concerning the earth's ozone layer. The first is the slow and constant deterioration of the amount of ozone in the earth's upper atmosphere at a rate of about 3 percent per decade. The second is the larger but seasonal decrease in the level of ozone in the atmosphere especially in the earth's Polar Regions, commonly called an ozone hole.

As we all know, the layer of ozone gas present in our atmosphere plays a very critical role in all chemical and biological process in our planet. Ozone filters out most of the very harmful ultraviolet rays from the sun and prevents radiation from reaching the earth's surface. Although, the levels of ozone in the atmosphere naturally rise and fall depending on factors such as altitude, temperature, and weather, the large amount of ozone lost in recent years cannot be attributed to natural factors alone.

Human-made chemicals and gases have a significant role in the phenomena of ozone depletion. Aerosols and Chlorofluorocarbons or CFCs, which are primarily used as propellant and as refrigerant, were found to be responsible for the depletion of the ozone layer. The depletion of the ozone layer poses a huge risk to all chemical and biological process on the earth's surface. Exposure to radiation, which would otherwise have been blocked by a "healthier" ozone layer, have various damaging effects on all living organisms on earth.

Because of this, there has been a continuing worldwide concern regarding the preservation of the ozone layer and the phasing out of ozone depleting substances (ODS). Countries and international communities have initiated actions towards the reduction of ODS and finding ways to curb the further depletion of the earth's vital ozone layer. A significant milestone in this effort was the Montreal Protocol on Substances That Deplete the Ozone Layer held in 1987 which encouraged the phase-out and reduction of ozone depleting substances over a time frame of several years.