Correct Answer - Option 1 : 3 mm
The correct answer is 3mm
The ozone layer over the earth's surface is approximately 3mm thick.
- The ozone layer is found in the upper part of the atmosphere called the stratosphere.
- It acts as a shield absorbing ultraviolet radiation from the Sun.
- UV rays are highly injurious to living organisms since the DNA and proteins of living organisms preferentially absorb UV rays, and it's high energy breaks the chemical bonds within these molecules.
- The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).
- Ozone gas is continuously formed by the action of UV rays on molecular oxygen and also degraded into molecular oxygen in the stratosphere.
The Montreal Protocol is an international treaty, was agreed on 16th September 1987, and entered into force on 1st January 1989, designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion.
International Day for the preservation of Ozone Layer is celebrated on 16th September every year.