What is the ozone layer?
A short, plain-language explanation of the ozone layer, why it matters, and the natural cycle that humanity has disturbed.
What is the ozone layer?#
The ozone layer is a thin shield in the stratosphere — roughly 15 to 35 km above Earth's surface — made of a natural gas called ozone (O₃). It absorbs most of the sun's harmful UV-B radiation before it reaches us. Without it, life on the surface as we know it would not be possible.
Source: UNEP "Ozone and You".
Why a "layer"?#
Ozone is rare even in the stratosphere — at most a few molecules per million. But spread across the upper atmosphere, those molecules are enough to filter the radiation that would otherwise damage skin, eyes, crops, and marine life.
A natural cycle, disturbed#
Ozone is constantly being created and destroyed in the stratosphere by sunlight. For most of human history this cycle stayed in balance. Starting in the mid-20th century, gases produced for refrigeration, foam-blowing, fire suppression, and aerosols began breaking that balance. Once these gases reach the stratosphere they release chlorine and bromine atoms that destroy ozone faster than nature can replace it.
What you'll find on this site#
- The Problem — how the gases we use damage ozone.
- Today and Tomorrow — the global recovery and the Kigali Amendment.
- Refrigerant register — what is permitted, what needs a permit, what is banned in Seychelles.
- Downloads — the Environment Protection Act 2001 and the Environment Protection (Ozone) Regulations 2000.