Ozone hole: what it is, causes and consequences

That of ozone hole it is a problem that we have been hearing about since the 1980s, an environmental issue that cyclically reminds us of the damage that man has caused to the environment. Although everyone has heard of this topic at least once in their existence, understanding why it is important to preserve the atmospheric ozone layer is not so immediate. What is ozone used for, how is the hole formed and what are the consequences it can have in terms of climate changes?

Before starting, it is good to underline a question that escapes most: the hole in the ozone layer is not eternal, nor immutable. It opens and closes cyclically, depending on the seasons and levels pollutionand its extension varies from year to year. Below is all the useful information.

What is the ozone hole

When we commonly talk about the ozone hole, we are more properly referring to two distinct phenomena that affect theozonosphere. This is located at a distance between 15 and 40 kilometers above the ground and is a layer of the atmosphere particularly rich in ozone, with a function that is anything but obvious. Simplifying, it is a real barrier, capable of bouncing in space ultraviolet rays of the sun, thus avoiding the spraying of radiation on the ground that is harmful to living beings.

Since the 1980s, due to pollution caused by man and the release into the atmosphere of substances that interfere with the natural ozone cycle, two worrying phenomena have been noticed:

• The ozone reduction in the stratospherewith a thinning of that natural barrier to ultraviolet rays;
• L’cyclical opening of a “hole”, i.e. such a high reduction in ozone levels as to make its protective function ineffective.

As a rule, the areas most affected by ozone loss on the globe are the Poles. This is because typically most stratospheric ozone is produced at tropical latitudes, then accumulates right above the Arctic and Antarctica.

The evolution since the 80s

The discovery of the existence of an ozone layer in the Earth’s atmosphere is relatively recent, in fact it dates back to the 1900s. However, it is in the 80s that international scientists discovered alterations to this natural barrier on Earth, most likely due to human action.

The term “ozone hole” was formalized in 1985, when it became evident that the ozone layer above the Poles was thinning year by year, so much so that it was losing its usefulness. At first it was thought that this reduction was due to some gassuch as CFCs (chlorofluorocarbons), normally contained in spray cans, refrigerators, household appliances and used in some industrial processes. So much so that, by 1990, more than 90 countries around the world banned their use and today they are banned almost everywhere.

Today, however, it is suspected that the causes are multiple since, although the elimination of CFCs has made it possible to reduce the average extent of the ozone hole by 20% compared to the peak reached in 2000, the problem seems to be far from an effective resolution . Between 2020 and 2021, a peak ozone hole extension of approximately 24.8 million square kilometers.

But hadn’t the ozone hole closed?

It must have happened to everyone, hearing about the ozone hole in the media, to ask themselves a more than legitimate question: “But hadn’t the hole in the ozone layer closed?“. Yes, since triumphal headlines have been launched several times in recent years about the closing of the hole in the ozone layer at the Poles, suggesting that the problem is definitively solved.

In reality, this is not the case. The formation and distribution of ozone in the stratosphere is cyclical, increasing in certain seasons and decreasing in others. So it happens practically every year that the ozone hole opens, particularly during the summer in the Northern Hemisphere, and then closes the following winter. So there are two questions:

• Extension: the ozone hole will open and close cyclically, it is therefore necessary to evaluate its extension, the greater the damage to the Earth;
• Resolution: the “definitive” closure of the ozone hole is not expected before 2050, provided that the objectives of containing climate change and reducing the release of pollutants into the atmosphere are managed.

What causes the ozone hole

But what are the causes of this alteration of the ozone layer? All researchers agree in identifying human origins of the hole in the ozone layer and, in particular, in the use of certain pollutants for decades.

CFCs (chlorofluorocarbons)

As already mentioned, i CFC – o chlorofluorocarbons – are considered the main causes of alterations in the ozone layer. These are gases that have long been used for the production of spray cansin the refrigeration circuits of refrigerators, freezers and air conditioners, as well as for the management of some industrial processes. They have the ability to increase the atomization of liquids, but also to ensure their rapid propagation.

However, once emitted into the atmosphere, these substances create destructive chemical reactions for ozone, reducing its quantity. As already mentioned, today CFCs are banned in many countries around the world, where they are no longer used for the production of sprays and household appliances. However, they can persist in some industrial processes or, again, in nations that have not yet adopted strict environmental limitations.

Other pollutants

For some time, researchers have also been studying other possible origins of the phenomenon of ozone reduction, although they consider CFCs to be the main cause. In particular, it emerged that some halogens, such as bromo and the chlorinecan activate destructive reactions for ozone.

Consequences of the hole in the ozone layer

But what are the consequences for the Planet and for man of the ozone hole and, above all, is this gas dangerous for man?

Is ozone dangerous?

When it comes to ozone, it is normal for some concerns to arise. In large concentrations, this gas is indeed harmful to humans. It is therefore legitimate to ask whether the quantities present in the atmosphere are not dangerous for human beings.

Ozone is used on Earth for the most varied purposes, such as the sterilization of environments, and its use requires adequate protection and correct ventilation to avoid serious effects. However, in nature it is found in very low concentrations, which do not represent a danger. An even truer fact when it comes to stratospherewhere the quantities are not only anything but dangerous – around 0.04 ppm – but also safe for human life, given the great distance from the ground.

Health consequences

The thinning of the ozone layer in the atmosphere can first of all have some consequences health consequences of man. Representing a barrier to solar ultraviolet rays, its reduction increases the risks linked to UV spraying. Among these:

• More frequent sunburns;
• Greater frequency of skin tumors;
• Damage to vision and eye function;
• Weakening of immune system.

Consequences on the environment

As is easy to imagine, the hole in the ozone layer also has consequences at an environmental level, not only on human and animal health. This is because:

• It favors the atmospheric overheating and, with it, climate change processes;
• It alters the survival of oceanic phytoplankton, with less oxygen production from the seas;
• Slow down agricultural productionsince crops are ruined by excessive exposure to ultraviolet rays;
• Blocking of chlorophyll photosynthesis by plants, with therefore a lower release of oxygen into the atmosphere and the inability of plants to absorb excess carbon dioxide.

As mentioned, a resolution of the ozone hole problem is not expected before 2050provided that all the environmental objectives set by the Montreal Protocol – specific to ozone – and the Paris and Glasgow agreements are respected.