How is Ozone formed in the stratosphere?

In the stratosphere, Ozone is formed by the dissociation of Oxygen molecules into Nascent oxygen followed by association of an Oxygen molecule and a Nascent Oxygen.

The chemical reaction involved is as follows:

O₂ + UV ----> [O] + [O]

[O] + O₂ ----> O₃

One use of Ozone is that it is used to treat infections, wounds and multiple diseases.

CFC ( chloro fluro carbon ) when mixed in atmosphere travels to upper atmosphere and gets disassociated generating highly reactive chlorine atoms which alter the bidirectional reaction of ozone formation. 

Natural step: 

O₃       <---------->  O₂ + O 

release of CFC: 

 CCl₂F₂ -----------------> CClF₂   + Cl^-

depleting reaction: 

O3 + Cl^-         ----------->         ClO^- +...

This way, the nascent chlorine disrupts the dynamic equilibrium of the ozone layer formation and depletion process. 

One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere by combining with some other compound. 

Harmful effect of ozone are primarily due to entering of ultraviolet rays in lower atmosphere. this includes: 

a. entering of UV rays,

b. causes no-melanoma skin cancer

c. damages vision of eyes and skin, 

d. Damages terrestrial and marine ecosystem. 

e. Raised temperature which can result in species being endangered and ultimately extinct which leads to ecosystem imbalance. 

The major cause of ozone layer depletion is the release of excess Green House Gases like Chlorofluorocarbons in the atmosphere.

Thus, following things can be done to control ozone layer depletion:

• Reduce dependency upon technologies that emit GHGs.
• Make use of alternative sources of energy that are environment-friendly.
• Reduce the industrial wastes that can potentially cause harm to the ozonosphere.
• Generate mass awareness programmes regarding this problem.