Why is the ozone layer getting thinner?

In the outer regions of the atmosphere(stratosphere), the layer of oxygen molecule O3 , called  ozone , protects the earth by absorbing the harmful rays belonging to the ultra violet spectra. The ultrra violet rays are harmful for the living beings - plants , animals or hamans. Ozone , after absorbing the ultra violet rays, splits into O2 and O and once again regenerates O3, the ozone. However ,trom  the man made chemicals , the free radicals of hyrooxyl and nitric oxide and atomic halogines that escape to the atmosphere react with the atomic oxygen. This cause the regenarion of O3 The Among these , the chloroflourocarbon(CFCl3) , is the major cause, to block the regeneration of the ozone.After use of the chemical, chloroflourocarbon, in refrigerators and air condtioners ,medicine,it escapes to atmosphere . The free chlorine atom has a higher reativity to with free oxygen atom to combine with to form chlorine monoxide:

O3 ---(after absorbing ultra violet rays)-----> O2   +   O

CFCl3 ---(ultraviolet ray)---> CFClO2  +  Cl

Cl +O3---ClO+O2

ClO+O3------------> Cl+2O2

From the above reaction we can see how the atomic halogines(Chlorine, Bromine ) have multi-cycles to prevent regeneration of  O3  from O2 ang O atoms .

Presently the thinning of ozone layers and the hole formations observed in the arctic regions. It is a dangerous trend  to the health of living beings that the thinning has been  gradually increasing over the years since 1970.