We explain what the ozone layer is and its characteristics. Also, how to protect it, what the ozone hole is, its consequences and more.
What is the ozone layer?
The ozone layer is a layer of the atmosphere of the Land which stands out for its high concentration of ozone. It extends between 15 and 45 kilometers from the Earth’s ground. It is also called ozonosphere.
By being capable of filtering most of the ultraviolet radiation that comes from the SunThe ozone layer works as a protective shield for the Earth. Some of this radiation is necessary for the development of life, but in high quantities it can be harmful to living beings.
The ozone layer was discovered by French physicists Charles Fabry and Henri Buisson in 1913.. The British physicist Gordon MB Dobson created, in 1924, a measurement system to calculate the thickness of the ozone layer, called the Dobson Unit (DU).
Characteristics of the ozone layer
Among the main characteristics of the ozone layer, the following stand out:
- It has a gaseous composition and is located in the stratosphere, which is the second layer closest to the Earth’s surface.
- It extends from 15 kilometers from the earth’s surface to 45 kilometers in altitude.
- The ozone molecules that make it up are made up of three oxygen atoms (instead of two, as in the oxygen molecule).
- It is essential for life, since it filters most of the ultraviolet rays that come from sunlight and that can be harmful to living beings.
- Its thickness is measured using the Dobson unit of measurement (DU), equivalent to 0.01 millimeters of thickness under normal pressure and temperature conditions.
- The main chemicals that affect it are chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC).
- Starting with the Montreal Protocol, signed in 1987, all countries in the world committed to reducing emissions of gases that damage the ozone layer.
Substances harmful to the ozone layer
Among the main substances harmful to the ozone layer are:
- Chlorofluorocarbon (CFC). It is a chemical compound containing chlorine, fluorine and carbon derived from saturated hydrocarbons or petroleum. It is one of the main causes of the disintegration of the ozone layer, because it can completely dissolve ozone molecules. It used to be used in all types of aerosols, solvents and air conditioners, but it is rarely used anymore.
- Hydrochlorofluorocarbon (HCFC). It is a compound similar to CFC, but, in addition to chlorine, fluorine and carbon, it contains hydrogen, which makes chlorine molecules more unstable when they come into contact with ozone in the stratosphere. Currently, it is practically out of use.
- methyl bromide. It is an organic compound that is used in the agricultural industry for fumigation. It was found to damage the ozone layer, although to a lesser extent than CFCs and HCFCs.
- Methylchloroform or trichloroethane. It is a substance that is currently prohibited for causing poisoning in living beings that have inhaled it and for damaging the ozone layer. It is an organic compound based on a complex mixture of hydrocarbons, with a liquid structure and an intense odor, which was used as a solvent in some industries.
- Carbon chloride or tetrachloride. It is a gaseous chemical compound that is currently banned due to its high level of toxicity to water, air and soil. It was often used as a fire extinguisher and in the production of refrigerants.
What is the ozone hole?
The ozone hole is a damaged area of the layer, which has a lower density or depletion of ozone molecules. This allows a greater passage of ultraviolet rays to the Earth’s surface, which is harmful to living beings.
The causes of ozone holes are of two types:
- Natural causes. They correspond to natural phenomena that can alter the concentration of ozone molecules. For example: volcanic eruptions, air currents in the stratosphere, solar activity or low temperatures that increase the levels of chlorine and bromine in the air, and which are capable of disintegrating ozone.
- Human causes. They correspond to activities and actions carried out by human beings that are harmful to the ozone layer. For example: the use of CFCs in air conditioning and refrigeration, or the manufacture of plastic foams and aerosols.
Starting in the 1970s, scientists detected that the concentration of ozone molecules was decreasing in various areas of the ozonosphere, especially in the polar regions. They called this considerable decrease in the width of the ozone layer the “ozone hole.”
So, In order to protect the ozone layer, the Montreal Protocol was signed in Canada in 1987., an environmental agreement signed before the United Nations (UN) by representatives of various countries. There, a commitment was established to reduce the global production and consumption of various substances harmful to the ozone layer, including CFCs and HCFCs. In 1994, the UN also proclaimed September 16 as the International Day for the Preservation of the Ozone Layer.
Currently, the ozone layer is gradually recovering due to the regulations implemented at the international level that regulate the marketing activities and use of harmful substances. Thanks to this, It is expected to be fully recovered by 2050.
Consequences of the depletion of the ozone layer
The reduction of the ozone layer has important consequences for life on the planet:
- Impact on human health. Chronic and excessive exposure to ultraviolet (UV) radiation can have negative effects on people’s health, such as skin cancer, premature skin aging, DNA damage, and a weakened immune system.
- Damage to marine life. Marine organisms, such as phytoplankton, zooplankton, corals and fish larvae, are particularly vulnerable to UV radiation, and excess exposure can affect their health and survival.
- Impact on terrestrial vegetation. Terrestrial plants can also be affected by excessive UV radiation, since it can cause alterations in photosynthesis and damage to their DNA.
- Effects on terrestrial fauna. Terrestrial fauna, such as insects, amphibians and reptiles, can suffer damage, mainly to the skin and eyes.
References
- Casatti, P. (2017). How UV rays affect plants. CONICET. https://www.conicet.gov.ar/
- Milo, A. (2023). Earth’s atmosphere: this is how the vital mantle works that allows life on Earth as we know it. National Geographic in Spanish. https://www.ngenespanol.com/
- Nuñez, C. (2020). What is the ozone layer and why is it important? National Geographic. https://www.nationalgeographic.es/
- Tarbuck, E. and Lutgens, F. (2005). Earth Sciences. An introduction to physical geology. Pearson Education.
