Ozone layer depletion

Ozone (O3) is a molecule made up of three atoms of oxygen (O), and is mostly found in the strato- sphere, where it protects us from the Sun’s harmful ultraviolet (UV) radiation. Although it represents only a tiny fraction of the atmosphere, ozone is crucial for life on Earth.

The stratospheric ozone layer forms a thin shield in the upper atmosphere, protecting life on Earth from the sun’s ultraviolet (UV) rays.  It has been called the Earth’s sunscreen.  In the 1980s, scientists found  evidence that the ozone layer was being depleted.  Depletion of the ozone layer results in increased UV radiation reaching the Earth’s surface, which in turn leads to a greater chance of overexposure to UV radiation and the related health effects of skin cancer, cataracts, and immune suppression.

Ozone depletion refers to the thinning of the ozone layer, which allows more UV radiation to reach the Earth’s surface Thinning ozone layer discovered in the 1980s .Ozone holes are observed at the south and north poles

There are natural processes that create and destroy ozone in the stratosphere. These processes regulate a balance of ozone and form the ozone layer. Ozone is created primarily by sunlight. When high-energy ultraviolet rays (UV-C) strike an oxygen molecule (02), they split the molecule into two single oxygen atoms, known as atomic oxygen. A freed oxygen atom then combines with an- other oxygen molecule to form a molecule of ozone (03).

Accelerated anthropogenic Depletion is mainly caused by chlorofluorocarbons (CFCs), halons, methyl chloroform and carbon tetrachlorides. These chemical substances are mainly eitherchlorine or bromine which can reach the stratosphere and catalytically break down ozone into oxygen. CFCs are odourless, non-flamable, non-corosive and nontoxic.   For this reason, scientist originally believed CFCs could not possibly have any effect on the environment. That is why it is widely used in refrigeration and air conditioning, in foam and plastic manufacturing and in aerosol sprays.

The Montreal Protocol on Substances that Deplete the Ozone Layer (a protocol to the Vienna Convention for the Protection of the Ozone Layer) is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. Montreal Protocol  of 1987  it was decided that the developed countries would totally ban CFC production by 2000 and the developing countries by 2010AD.

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