Question

There is a hole in the ozone layer. What do you understand by this?

Answer 1

Hint: The region of the stratosphere (part of the atmosphere) where high concentrations of ozone are found is called the ozone layer. It prevents harmful ultraviolet rays (UV rays) from passing through the atmosphere and damaging life on earth.

Complete answer: The thinning of the ozone layer is known as ozone depletion. There are certain substances called ozone-depleting substances (ODS), such as halocarbon refrigerants, propellants, solvents and foam blowing agents like chlorofluorocarbons (CFCs), which are responsible for ozone depletion. For instance, if the CFCs reach the stratosphere, where the ozone layer is present, the CFCs break down into chlorine (with other substances) due to the ultraviolet rays. The chlorine atom then breaks the ozone molecule into an oxygen molecule. One atom of chlorine can destroy more than thousands of ozone molecules. It happens so quickly that ozone molecules can not be replaced. By this, the ozone layer gets thinner. Thus, the ozone hole is a region of the stratosphere where there are extremely low concentrations of ozone. This hole can be seen around the southern hemisphere (over Antarctica). The ozone layer has the potential to absorb about 99 % of harmful ultraviolet rays coming from the sun, which could damage life on earth. If the harmful ultraviolet rays fall directly on humans then, they would develop skin diseases.

Note: After the adoption of the Montreal Protocol (1987), which bans the production of ozone-depleting chemicals, ozone levels have been stabilized and it is expected to reach pre-1980 levels by around 2075.