Question

How is ozone formed in the uppermost atmosphere? Why is damage to the ozone layer a concern to us? What causes this damage?

Answer 1

Hint: Ozone is the layer which protects Earth from the harmful UV rays. Ozone is formed in higher atmosphere as well as near earth’s surface. The ozone formed in higher atmosphere due to natural changes is stratospheric ozone and the one forming near earth’s surface as a result of various natural and chemical changes in tropospheric ozone.

Complete answer: Ozone is formed in the stratosphere naturally by solar ultraviolet radiations (UV) and oxygen molecules. It makes up about 21% of our atmosphere.
Firstly, the solar radiation breaks up one oxygen molecule into two oxygen atoms-

 $${{O}_{2}}\xrightarrow{h\nu }O+O$$  

Then, these highly reactive oxygen atoms react with another oxygen molecule to give ozone-

 $${{O}_{2}}+O\to {{O}_{3}}$$  

These reactions take place continuously whenever solar radiation is falling on them due to which the largest amount of ozone is formed in this layer itself.
Now we will discuss why damage to ozone is a concern to us-
As we know, ozone is the layer which protects our planet from the harmful ultraviolet rays of the sun which causes skin cancer. Damage to the ozone layer will cause UV-rays to reach us effectively and cause skin related diseases.
Also, atmospheric ozone plays a huge role in maintaining the temperature of our planet. It absorbs the infrared radiations emitted by earth’s surface and it also absorbs the ultraviolet radiation which heats up the stratosphere.

Ozone layer is damaged by-
-CFC (chlorofluorocarbon) used in refrigerants as a cooling agent is the main cause of ozone depletion. CFC causes chemical reactions which break down the ozone molecule hence, decreasing its capability of absorbing UV rays.
-When chlorine or bromine radical come in contact with ozone, they destroy the ozone molecule and one chlorine radical can break over thousands of ozone molecules as it follows a chain reaction.

Note: It is important to know that greenhouse gases are not the cause of depletion of ozone. The root cause of ozone layer depletion is CFCs. Ozone depletion does not cause global warming. These two are different environmental concerns but have the common cause- pollutants released by humans into the atmosphere.