Everything you need to know about the ozone layer
08 December 2020 | Aimee Tweedale
Cast your mind back to the 1980s, and you might remember the powerful smell of hairspray. Chemicals in that hairspray were responsible for not only some of the decade’s boldest hairstyles, but also perhaps its most significant environmental discovery: the hole in the ozone layer.
The story of what happened next, and how countries around the world came together to close the ozone layer hole, is one that gives hope in the fight against global warming.
But what is the ozone layer? How far is it above the earth? And is it true that it’s now healing?
Read on to find out everything you need to know.
What is the ozone layer?
The atmosphere surrounding Earth is made up of several layers, each of them serving a different purpose. The ozone layer is – of course – the layer with the highest concentration of ozone. This helps it to protect the Earth from harmful ultraviolet (or U-V) rays from the sun.
The lowest part of the Earth’s atmosphere is the troposphere. This is what we can see and feel all around us, and it’s where all our rain, snow, and other weather happens. The ozone sits just above this, in the stratosphere, which is part of the upper atmosphere. That’s about 9 to 18 miles above the Earth’s surface1.
What is ozone, anyway?
Ozone is a chemical compound made up of three oxygen atoms (otherwise known as O3).
Down here on Earth, ozone can be really dangerous, as it’s toxic to plants and animals. If you inhaled ozone, it would poison you. But up in the stratosphere, it’s vital: it protects us from the sun.
What does the ozone layer actually do?
The main role of the ozone layer is to absorb UV rays from the sun. Think of it like a giant layer of sunscreen.
Why’s it so important? Without it, we literally wouldn’t be able to live on Earth. UV rays cause sunburn, eye damage, and skin cancer – so the ozone layer offers us protection. If we had no ozone layer, the sun’s rays would be so powerful that they would sterilise the Earth’s surface.
What is ozone layer depletion?
When people talk about ‘ozone layer depletion’, it’s another way of talking about the hole in the life-saving layer.
The ‘hole’ is where the ozone has been depleted – meaning there’s less of it than there should be.
In 1974, two chemists named Mario Molina and Sherwood Rowland were the first to warn the world that certain chemicals, such as chlorine, could damage the ozone layer. By 1985, a group of English scientists confirmed that there was a hole in the layer above Antarctica2.
Ozone depletion is mostly caused by human activity. Read on to find out more about how we created the hole in the ozone layer, and how it began to heal.
Where is the hole in the ozone layer?
The hole is above the South Pole. The layer changes over time, so the hole doesn’t appear all year round – but it can usually be seen above Antarctica during Spring.
What caused the ozone hole?
The hole is thought to have been caused by ozone-depleting substances that were released into the atmosphere. These are chemicals, usually containing chlorine or bromine, that cause a reaction which breaks down ozone molecules. This leads to ozone loss.
Ozone depleting chemicals include:
- Chlorofluorocarbons (or CFCs)
- Halons (similar to CFCs, but these contain bromine)
- Any other gases containing chlorine or bromine, e.g. methyl bromide
CFCs are particularly bad news. Chlorine is great for keeping swimming pools clean, but when it travels to the ozone layer in the form of a gas, it’s deadly. Just one chlorine molecule can wipe out 100,000 ozone molecules3 – so it takes a long time to undo the damage these chemicals cause.
But back in 1985, CFCs were everywhere. They were used in aerosol sprays, like deodorant and hairspray, air-conditioning units, fridges, freezers, and Styrofoam packaging4.
Once it was discovered that these substances had created a hole in the ozone layer, scientists and world leaders acted quickly. The Montreal Protocol on Substances that Deplete the Ozone Layer was signed by all 197 countries in the United Nations in 1987.
The Montreal Protocol set out new rules about how ozone-depleting substances can be used. It also started to phase out some of these chemicals, like CFCs, completely.
Is the ozone layer healing?
Recently, you might have heard that the Earth’s ozone layer is healing. The rumours are true: a scientific paper published in 2020 confirmed that the hole is shrinking, and the ozone layer is repairing itself.
The turnaround in the ozone layer is an example of the real impact people can have on the environment when many countries work together quickly. Since 2000, thanks to the Montreal Protocol, CFCs have been on the way out, and the ozone hole has shrunk as a result.
Still, we need to stay aware of how our actions are impacting Earth. Some scientists are now worried about chemicals used to replace CFCs – and we’re not sure yet what the long-term impact of those will be5.
As greenhouse gases heat up the Earth, the fight against climate change is just beginning. Find out more about what the climate crisis is, and what changes you can make at home to reduce your carbon footprint.
What can damage the ozone layer?
Many of the culprits causing the original hole in the ozone layer – such as CFCs – have now been banned. But there are still some harmful ozone-depleting chemicals out there – for example, in old cars and appliances.
Watch out for these 5 everyday things that could be damaging the Earth’s ozone layer.
5 surprising things that can harm the ozone layer
- Farming animals: it’s no secret that the meat and dairy industry has a huge impact on the planet, but it’s also hurting the ozone layer. Nitrous oxide, the gas given off by animal manure and artificial fertilisers, is now the leading cause of ozone-depletion6.
- Air conditioning in old cars: if you drive a car built in the 1980s or 1990s, before the CFCs ban came in, then you should be careful about using the air con. You might also need to follow special rules to get rid of it safely. Find out more here.
- Old refrigerators: likewise, if you’ve got a fridge or freezer from before 1994, it might be time to think about replacing it.
- Cheap wood: into DIY? When you’re stocking up on wood, make sure it hasn’t been treated with methyl bromide – it should be marked with ‘MB’ if it has.
- Outdated fire extinguishers: if you’ve got an old fire extinguisher, it might contain halons – which are bad news for the ozone layer. Make sure you dispose of it safely, and replace it with a halon-free alternative.
The ozone layer may be healing now, but some chemicals used to replace CFCs are contributing to climate change. The next battle our generation faces is reducing greenhouse gases and carbon emissions, in the face of the climate crisis.
Here at OVO, we’re working hard at our mission to become a net zero carbon business by 2030. Read about how we’re working to reduce our carbon footprint here.
Interested in powering your home with 100% renewable electricity7 and 100% carbon-neutral gas, and planting 5 trees every year? Make the switch to OVO Beyond, and join us in our journey to zero carbon.
Sources and references
7 The renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on REGO certificates and how these work.