Atmospheric Structure and Ozone

Ozone hole refers to the depletion of the ozone layer present in the stratosphere of the atmosphere. The chlorofluorocarbons are the paraffinated halogens that enter the stratosphere with winds and split up when exposed to the UV rays. They release reactive chlorine which further reacts with the ozone to release diatomic oxygen. The ozone hole shows a low concentration of ozone which is less than 220 DU. It is more prominent over Antarctica due to polar vortex and formation of the polar stratospheric clouds.

Among the five layers of the earth's atmosphere, ozone is present in the stratosphere which absorbs UV radiation before it reaches the ground. The main cause of ozone depletion is manufactured chemicals especially CFCs, these compounds reach the stratosphere by winds, where they release halogen atoms through photodissociation and cause the breakdown of ozone into oxygen. The ozone hole formed due to this increase the exposure of direct UV rays on earth carrying the potential risk of skin cancer and other negative effects

CFCs (Chlorofluorocarbons) are the primary chemical compounds identified as the main cause of ozone layer depletion.

High-flying aircraft, particularly supersonic jets, release nitrogen oxides and other pollutants directly into the stratosphere. These substances catalyze the breakdown of ozone molecules, leading to the depletion of the ozone layer.

Chlorine free radicals act as catalysts in the stratosphere, where they react with ozone (O3) to form oxygen (O2) and chlorine monoxide. This process destroys ozone molecules, which is the primary cause of ozone layer depletion.

Scientific evidence regarding the depletion of the ozone layer, particularly the role of CFCs, gained significant attention and was widely published in the 1980s following the discovery of the Antarctic ozone hole in 1985.

Chlorofluorocarbons (CFCs) and carbon tetrachloride (CCl4) are both significant ozone-depleting substances. Carbon tetrafluoride (CF4) is also recognized as a greenhouse gas with potential atmospheric impacts, making all listed options contributors to the broader issue.

Ozone depletion in the stratosphere has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole. UV radiation of wavelengths shorter than UV-B, are almost completely absorbed by Earth's atmosphere, given that the ozone layer is intact. But, UV-B damages DNA and mutation may occur. It causes aging of skin, damage to skin cells and various types of skin cancers. In human eye, cornea absorbs UV-B radiation, and a high dose of UV-B causes inflammation of cornea, called as snow-blindness, cataract, etc. Such exposure may permanently damage the cornea. Thus, the correct answer is option D.

Ozone layer is a region of concentration of ozone molecule. $O _3 (O _2+ O)$ in the earth's atmosphere. The layer lies in the stratosphere at an altitude of 18-50 kms. The ozone layer naturally Shields earth's life from the harmful effect of the Sun's ultraviolet radiations.

The UV-C radiations breakdown the bonds in the chlorofluorocarbons (CFCs) to release the chlorine monoxide and the nascent chlorine. These further react with the ozone to split it into ordinary oxygen molecules. The oxygen molecules are further broken down into nascent oxygen, which acts as the radicle. 

Polar spring, also known as the Antarctic Spring is the period from late August to early October and the strong westerlies circulate around the Antarctic continent creating a polar vortex. The polar vortex results in the formation of the polar stratospheric clouds which trap most of the gases including the ozone-depleting factors like CFCs, methyl bromide etc.