What is ozone (O3)?

Ozone (O₃) is a pale blue gas constituted of three oxygen atoms that is present in different layers of our atmosphere.

Usually, O₃ is not emitted into the air directly but is developed at ground level through a chemical reaction. Ozone layer depletion does not cause global warming, but it can be damaging to human health. It is one of the planetary boundaries defined by the Stockholm Resilience Center.

According to NASA, negative shifts in the ozone layer are offset by positive changes in human behaviour, which allows the ozone layer to reform.