In the space of a few weeks the world has changed at a rapid rate as a result of the Covid-19 pandemic. Wherever you are reading this post from it is highly likely that people in your country will be suffering. During these times I think we all need to try to be positive, and as such I thought we could have a look at an international environmental success story. A chink of light in an otherwise gloomy world.
Ozone, made up of three oxygen atoms, it is present in the stratosphere (part of the atmosphere around 10km to 50km from the earth’s surface) and protects life from harmful ultraviolet radiation (UV) from the sun, this is sometimes known simply as good ozone. It acts like a screen in the atmosphere. Ozone released at low levels is a pollutant, for example, it can be formed from the breakdown of vehicle emissions or chlorinated solvents, this is often called bad ozone.
The Bad News First
Being exposed to significant quantities of UV can have a significant effect on health, causing increased risk of skin cancer, crop damage and cataracts. Ozone can be relatively easily destroyed by combining with molecules that contain elements such as chlorine, bromine and fluorine (all halogens). Substances containing these molecules are often known as ozone depleting substance (ODSs).
The release from human activities of ODSs has led to damage to the ozone layer that includes a gradually lowering of the total quantity of atmospheric ozone in addition to a rapid drop of ozone in the polar regions of the planet. This depletion is particularly pronounced over the south pole. In this area, ODSs freeze on to ice crystals in the polar winter; allowing ozone levels to increase, when the polar spring arrives the ODSs are released in one big hit causing an ozone hole to form. NASA’s Ozone Watch has been tracking ozone levels since 1979 to the present day for both the northern and southern hemispheres, take a look at the movies on the ozone watch website to see how ozone has been depleted over that time period.
The problem with a lot of ODS is that they have a very long time in which they are active in destroying ozone in the atmosphere. A molecule of chlorofluorocarbons, (formerly used in refrigeration, propellants and in cleaning) can last for around a century during which it will destroy around a hundred thousand ozone molecules.
Now for The Good News
Obviously if this situation was left unchecked then it would have severe consequences. After piecemeal attempts to deal with the problems nationally, the international community decided to get together and develop framework international legislation, signing the Vienna Convention for the Protection of the Ozone Layer in 1985. In 1987 secondary legislation was made from the Vienna Convention which is known as the Montreal Protocol on Substances that Deplete the Ozone Layer. The protocol aims to phase out the production of key man-made ODSs, with differing dates based on whether the country is classed as ‘developed’ or ‘developing’ as shown in the table below:
The Protocol has led to the phase out of 99% of ODSs from, refrigerators, air conditioners and other products. This is a good piece of legislation structurally, as it aims for the complete phase out of the manufacture of ODS across the planet. In terms of risk control hierarchy, it aims to eventually eliminate ODSs.
There is evidence to show that the ozone layer is now in a period of recovery. For example the work done by Antara Banerjee and her team in recently published article in Nature provides evidence of changes in wind patterns as a result of the recovering ozone layer. The United Nations/World Metrological Association assessment studies are showing that parts of the ozone layer are recovering at a rate of 1-3% every ten years.
As ODSs have such a long residency time in the atmosphere it will be many years before their impact is eliminated. In a recent New Scientist article it is postulated that full recovery of the ozone layer could take up till at least 2060. We have a long time to wait but at least progress is being made.
Hope for The Future
I think this case study should give humanity hope in that international treaties do actually work and that the damage that has been caused to the planet can be ameliorated. We face many challenges both environmentally and socially within society at the moment, such as climate change the Covid-19 pandemic and many more. However, if there is cooperation these trans-boundary problems that have the potential to cause significant hardship around the world can be halted.
John Binns BSc (Hons), MSc, MSc, MIEMA
With over 19 years’ experience working in environment management, John Binns BSc (Hons) MSc MIEMA is an experienced environmental tutor and consultant with knowledge of health and safety management.