Ozone Layer Depletion: Meaning, Causes, Effects

What is ozone layer depletion?

The ozone is a layer of gases in the stratosphere, which is a thick (20 km thick, to be precise) layer of gas that rests about 30-50 km above the surface of the earth. It is mainly made up of ozone gases, and the key gas is O3 which is made of molecules consisting of three oxygen atoms all bonded together.

Ozone depletion refers to the decline in, and thinning of, the ozone layer – something which has been going on since the 1970s. This decline is seen right throughout the ozone layer, but it is particularly noticeable above the polar regions in the springtime.

In fact, in the 1980s, the phenomenon of ozone depletion was discovered when it was found that there was actually a hole in the ozone layer above Antarctica.

Causes of ozone layer depletion.

The causes of ozone layer depletion are almost all man made. Here we look at the key causes of the thinning of the ozone above our planet:

The main causes of ozone depletion are the various uses of CFCs: CFCs are chlorine based substances which used to be widely used in aerosols, refrigerants, and in several manufacturing plants. These substances, released into the air, had a very damaging effect on the ozone because chlorine is deadly to ozone molecules. Just one atom of chlorine is enough to destroy around 100, 000 molecules of O3. CFCs were banned in the 1980s as soon as it was discovered that they were substantially destroying the ozone layer. Many common substances contained CFCs before they were banned, including the styrofoam which was widely used in cups and in packaging.

CFCs get into the ozone layer by the action of the winds, which blows them up into the stratosphere. O3 molecules are already more unstable that the O2 molecules which consist of the oxygen in the lower parts of the atmosphere, including the air that we breathe. So, all that it takes is for the chlorine in the CFCs to start mixing with the O3 molecules and these O3 molecules will break down into an O2 molecule and a single free floating oxygen atom, catalysed by chlorine. One small piece of good news is that not all chlorine has this direct negative effect on the ozone layer. For example, it is fine to use chlorine in your swimming pool as far as the ozone is considered because this type of chlorine does not pose any danger of being swept up into the stratosphere where it can interfere with our ozone.

The sun’s rays also act to both break up and put back together O2 and O3 molecules. However, this is more of a natural process: the sun is not vastly and potentially irrevocably destroying our precious ozone in the way that human use of CFCs was.

Thankfully, now that CFCs have been banned, the ozone layer has begun to heal itself and the worrying hole in the ozone is starting to get smaller and smaller. However, it is important that we are aware of the negative effects of ozone depletion, so that we never release harmful chlorine based substances up towards the stratosphere again.

The effects of ozone depletion.

The effects of ozone depletion are all negative ones, and they potentially affect every person on this planet. Here are five of the main results of a depleted ozone layer:

1. More skin cancer: the ozone works to absorb harmful UV rays from the sun before they can reach earth. A depleted ozone layer means that more UV rays hit our skin and this is a major cause of a variety of skin cancers.

2. More people suffering from cataracts: you may have heard that staring at the sun is bad for your eyes – and this is taking into account the fact that the ozone has already filtered a lot of the UV rays out of the atmosphere before they can reach our eyes. High intensity UV rays can rapidly cause cataracts to develop in the human eye, and a depleted ozone layer will thus result in many, many more people suffering from these kinds of eye problems.

3. A warmer earth: scorching temperatures are a result of more sunlight being able to penetrate through the stratosphere thanks to a less thick ozone. This leads to all kinds of negative effects, from melting ice caps to rising sea levels and severe droughts.

4. An unstable climate: climate change and overall global warming can result in very unstable weather patterns which include unseasonal snow storms, larger than usual hurricanes, and other freak weather patterns. This can be very dangerous for human life, as well as disrupting agriculture and displacing millions of people all of a sudden.

5. People get sunburned more readily: sunburn is a sign that your skin is being damaged by the sun. The fact that more sunburn, more quickly is one of the milder effects of a depleted ozone layer just goes to show just how severe all of the other effects are.


It’s time to take care of our whole planet. The story of ozone layer depletion shows us two key things.

  • First of all, it shows that human beings can cause substantial harm to the environment in just a short period of time (CFCs had only been used for about a decade before the hole in the ozone layer was discovered).
  • Secondly, though, it shows that when humans take concrete action, we can start to heal and to reverse the damage that we have done to our planet.