Stratospheric ozone depletion cause – UGC NET Question

Stratospheric ozone is depleted when chlorine and bromine atoms, released from certain man-made chemicals, catalyse reactions that destroy ozone molecules. Chlorofluorocarbons (CFCs), halons and some related halogenated compounds are particularly important sources of these atoms. They are stable in the lower atmosphere but break down under strong UV radiation in the stratosphere, releasing ozone-destroying radicals. Consequently, these substances are recognised as the main cause of the ozone hole, making option C correct.

Option A:
Option A is incorrect because sulphur dioxide and nitrogen oxides are more closely associated with acid rain and tropospheric pollution. They do not play the dominant role in stratospheric ozone depletion.

Option B:
Option B is incorrect since carbon dioxide and methane are key greenhouse gases driving climate change, but they do not directly cause the ozone hole. Climate change and ozone depletion are related but distinct problems.

Option C:
Option C is correct as CFCs and similar compounds were widely used in refrigeration, aerosols and foam blowing. Their regulation under the Montreal Protocol has led to gradual recovery of the ozone layer.

Option D:
Option D is incorrect because oxygen and nitrogen are natural components of the atmosphere and are essential in forming and maintaining the ozone layer. They are not pollutants responsible for its depletion.