What Is Damaging the Ozone Layer

How ozone depletion was discovered

During the 1970s, scientists identified that certain man-made chemicals were breaking down ozone in the upper atmosphere. British scientist James Lovelock first detected CFCs in the atmosphere, and subsequent research by American scientists established that these chlorofluorocarbons were destroying the ozone layer.

CFCs were first developed in the 1930s by American chemist Thomas Midgley. At the time, they seemed like a breakthrough. They were cheap to produce, did not catch fire, and appeared completely safe to handle. Midgley was celebrated for his work, though his inventions ultimately caused severe environmental harm. He also invented leaded petrol, which we now know caused widespread environmental and health damage.

Why CFCs were so widely used

For decades, CFCs were highly regarded across industry. Their properties made them ideal for a wide range of uses in industry and everyday products.

Refrigeration was one of the first applications. Over time, CFCs became standard in air conditioning systems, aerosol cans, and various industrial processes. They provided the propellant in products ranging from hairspray and air fresheners to paint and cleaning solvents. Before alternatives were developed, they were also used as propellants in metered dose inhalers for asthma treatment.

Because they seemed non-toxic and stable, few people questioned whether they might cause harm elsewhere. It took several decades before researchers understood what was happening high above the Earth's surface.

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What makes a substance ozone depleting

CFCs contain carbon, chlorine and fluorine. When released into the atmosphere, they eventually drift up to the stratosphere. There, ultraviolet light breaks them apart, releasing chlorine atoms that react with ozone molecules and destroy them.

A single chlorine atom can break down thousands of ozone molecules before it becomes inactive. This is why even relatively small quantities of CFCs can cause significant damage over time.

CFCs are the best known ozone depleting substances, but they are not the only ones. Other chemicals that harm the ozone layer include:

• Halons, once widely used in fire extinguishers
• Carbon tetrachloride, used as a solvent and in some manufacturing processes
• Hydrochlorofluorocarbons, or HCFCs, which were developed as partial replacements for CFCs but still cause some ozone damage
• Methyl bromide, used in agriculture as a fumigant

These substances vary in how much damage they cause and how long they remain in the atmosphere. Certain CFCs and halons can persist for over a century.

Where things stand now

The Montreal Protocol, signed in 1987, committed countries around the world to phasing out ozone depleting substances. The UK has been part of this international effort from the start, and domestic regulations now ban or restrict the production and use of most harmful chemicals.

The Environment Agency and the Department for Environment, Food and Rural Affairs handle enforcement in the UK. Businesses that work with refrigerants or other controlled substances must follow strict rules on handling, recovery and disposal.

Progress has been significant. Atmospheric concentrations of many ozone depleting substances have fallen. According to projections from the World Meteorological Organization and the United Nations Environment Programme, the ozone layer over mid-latitudes is expected to recover by around 2050, with polar regions following by about 2060.

Pre-1990s equipment, such as older fridges or air conditioning units, may still contain CFCs or HCFCs. If you need to dispose of such items, contact your local council about proper procedures. Correct disposal prevents these substances from escaping into the atmosphere and causing further damage. For current regulations and guidance on controlled substances, see the ozone depleting substances section on GOV.UK.