An Invisible Shield: The Ozone Layer

By: Edson Marín Jara and Jhoselin Alejandra Ticona Choqueña

In 1839 the German chemist Christian Friedrich Schonbein discovered a gas that he called ozone and it wasn’t until 1929 that the First International Ozone Conference was held (Martín Arribas, 1994).

In 1913, the French physicists Charles Fabry and Henri Buisson discovered the ozone layer located in the stratosphere between 20Km and 50Km altitudes, this layer contains 90% of the total ozone present in the atmosphere and is responsible for the absorption of 97 - 99% of ultraviolet radiation from the sun (Universidad da Coruña, 2017) protecting us from skin cancer and cataracts as well as affecting our immune system (National Geographic, 2018).

The ozone layer is a fragile band of gas that protects the Earth from the harmful effects of the sun's rays, thus helping to preserve life on the planet; however, the use of certain chemical products damaged it, endangering our existence and that of the rest of the living beings on the planet. A joint international effort has made it possible to eliminate and reduce the use of substances that deplete the ozone layer, contributing not only to protecting it for current and future generations but also to improving the results of initiatives aimed at dealing with climate change ( United Nations, 2021).

In 1947, scientists Mario Molina and Sherry Rowland made their successful discoveries known, pointing out that some chlorofluorocarbons (CFCs), being insoluble in water, remain in the stratosphere, decomposing by solar ultraviolet radiation, releasing chlorine atoms that short time they destroy billions. of ozone molecules (Martín Arribas, 1994). Scientists have also discovered other substances that deplete the ozone layer, such as halocarbons, methyl bromide, methyl chloroform, carbon tetrachloride, dichloromethane, hydrofluorocarbons (HCFCs), and halons (United Nations, 2021).

In 1985, a hole in the ozone layer was discovered in Antarctica (Farman et al., 1985), which is currently the largest, caused mainly by chlorofluorocarbons whose lifespan is between 50 and 100 years (National Geographic, 2018). Over time, the ozone layer has been recovering thanks to the ban on chlorofluorocarbons (CFCs) present in many household cleaning products. These chemical substances were abandoned after the introduction of the Montreal Protocol in 1987 (BBC News Mundo, 2017)

However, dichloromethane, also known as methylene chloride, was not included in the protocol because it is short-lived (that is to say, it breaks down after about five months). However, it releases chlorine that can destroy ozone if it reaches the ozone layer in the stratosphere (BBC News Mundo, 2017).

According to Ryan Hossaini et al., (2017), the levels of dichloromethane in the atmosphere increased by 8% per year between 2004 and 2014. If this trend continues, computer models show that the recovery of the ozone layer, originally projected for 2065 ( without taking into account the emissions of this substance) could take another 30 years, that is, the recovery would not be complete until 2095 (BBC News Mundo, 2017).

Some recent scientific findings point out that the ozone depletion in the Arctic polar vortex could intensify by the end of the century unless global greenhouse gases are rapidly and systematically reduced. In the future, this could also mean more UV radiation exposure in Europe, North America, and Asia when parts of the polar vortex drift south (World Meteorological Organization, 2021).

Numerous investigations have been carried out over the years to find new ways to assess the impact of substances that damage the ozone layer to develop more effective methods for its protection.

Recently, a new method for assessing the impact of substances that damage the ozone layer has been developed by University of Cambridge researchers and colleagues, known as the Integrated Ozone Depletion (IOD) metric, which provides a tool for policymakers and scientists to measure the effects of unregulated emissions of substances that deplete the ozone layer, and evaluate the effectiveness of protection measures (Cambridge Independent, 2022).

The government, the private sector, and civil society play an important role in the protection and restoration of the ozone layer. Governments around the world signed the Montreal Protocol in 1987, imposing global restrictions on the production and consumption of nearly 100 artificial chemicals that can cause ozone depletion, thanks to this measure up to the present day, the total amount of ozone in Antarctica has no longer continued to decline and has begun to slowly recover, and climate change caused by long-term ozone depletion has also shown a significant “stagnation” in recent years (Wenshou Tian, 2022).

However, even with the most sophisticated technology and the most precise measures to prevent the deterioration of the ozone layer, this won’t do much if we continue polluting as we have done for generations. Currently, most of society only cares about their comfort and well-being but they don't bother to find out if they pollute too much or overuse pollutants.