Ozone layer is a region of Earth’s stratosphere that absorbs most of the Sun’s ultra violet radiation. The ozone layer is also called as the ozone shield and it acts as a protective shield, cutting the ultra-violet radiation emitted by the sun. The ozone shield is being damaged by chemicals released on the Earth’s surface notably the chlorofluorocarbons widely used in refrigeration, aerosols, chemicals used as cleaners in many industries. The decline in the thickness of the ozone layer over restricted area is called Ozone hole.

CSS stands for Carbon capture and storage. It is a technology of capturing carbon dioxide and injects it deep into the underground rocks into a depth of 1 km or more and it is an approach to mitigate global warming by capturing CO 2 from large point sources such as industries and power plants and subsequently storing it instead of releasing it into the atmosphere. It is also known as Geological sequestration which involves injecting CO 2 directly into the underground geological formations.