What emissions from human activities lead to ozone depletion? And what are the principal steps in stratospheric ozone depletion caused by human activities? (AS1)

The emissions of chlorofluorocarbons (CFCs) from some industries and from household consumer products such as refrigerators and air conditioning systems. These gases bring chlorine and bromine to the stratosphere, which cause depletion of the ozone layer.

Principal steps in ozone depletion:

Step 1. CFCs released from human activities.

Step 2. CFCs rise into the ozone layer in the stratosphere.

Step 3. In the stratosphere, high-energy UV radiations from the Sun breaks CFC molecules, releases free chlorine (Cl).

Step 4. The free chlorine atoms react with ozone, to convert it to plain molecular oxygen. One chlorine atom can destroy up to 15,000 ozone molecules. In this manner even, minute quantities of CFCs reaching the stratosphere can be disaster for the ozone layer.

Step 5. A depleted ozone layer means that more UV radiations can get through it.

Step 6. More UV radiations coming to the earth has harmful effects on humans, animals and plants.