What is ozone hole and how does it formed?

Answer 1

In the upper atmosphere or stratosphere, there is a thin layer of ozone, which is O3, a form of oxygen, which protects against the more dangerous form of ultraviolet radiation that is part of sunlight. This used to cover the entire planet Earth, but in recent decades, the ozone has disappeared over the polar regions, creating holes in the ozone layer. We have been manufacturing chemicals called chlorofluorocarbons, which includes a popular refrigerating agent called freon, which when they escape into the atmosphere, eventually reach the stratosphere, and destroy ozone by catalyzing the transformation of ozone into the more usual form of oxygen, O2. This happens faster at lower temperatures because ice crystals also assist in the process (the chlorofluorocarbons become attached to the ice crystals and this makes them more effective catalysts). The manufacture of chlorofluorocarbons has been restricted by new regulations since this effect was noticed, and the holes in the ozone layer are shrinking.