Ozone Depletion from atmosphere:

• The chlorine atoms are released by the dissociation of chlorofluorocarbons (CFC's) are responsible for the depletion of ozone layer.
• The release of CFC is confined to the following activities.

1. Refrigeration
2. Air conditioning
3. Extinguishing Fires
4. Cleaning Solvents in industries
5. Blowing agents in plastic industries
6. Solvents used in paint industry.

• One chlorine atom (CI) is estimated to destroy upto 1 lakhs ozone molecules. If it is continued for a longer period the natural filter of ozone layer will be totally lost and due to UV radiation.
• The total life will be in danger, Together with CI the other substances making the ozone depletion fast are, carbon tetra choloride, Halon and Methyl Bromide.

Chemical Reactions in Ozone Depletion in nature:

Ozone depletion by UV radiations

1] An oxygen molecules reacts in presence of a photon from solar radiations and forms two oxygen radicals:

$hv+O_2\to 2O$

2] These Oxygen radicals then react with molecular oxygen and produce ozone: 

                                                           $O_2+O\to O_3$

 Ozone then reacts with an additional oxygen radical to form molecular oxygen:

$O_3+O\to 2O_2\ \ \ \ \ \ \ OR\ \ \ \ \ \ \ O_3+hv\to O_2+O$

Ozone Depletion by CFC molecules (By Chlorine)

CFC molecules arc made up of chlorine, fluorine and carbon atoms [CCl3F(g)l which are extremely stable. This extreme stability allows CFC's to slowly make their way into the stratosphere

Chlorine is released by CFC in sunlight by following reaction:

$CCl_3\ F(g)\to CCl_2F+Cl(g)\ \ \ \ \ \ \ \ \ \ \ \ (Cl \ Released)$

Chlorine acts as a catalyst by following pathway / reactions ozone layer gets destroyed

$Cl(g)+O_3(g)\to ClO(g)+O_2(g)....................(Step \ I)\\ ClO(g)+O(g)\to O_2(g)+Cl(g)........................(Step \ II)\\ O_3(g)+O(g)\to 2O_2...................................(Overall\ reaction)$

Ozone depletion by Nitric oxide: (Created from nitrous oxide)