Ozone is a highly reactive allotrope of oxygen, meaning it's a form of oxygen with a different structure than the standard diatomic oxygen (O2) we breathe.

Here's why ozone has a pungent odor:

* Highly reactive: Ozone is a powerful oxidizer, meaning it readily reacts with other substances. This reactivity contributes to its distinctive smell.

* Unstable: Ozone is unstable and readily decomposes back to oxygen, which is why it's rarely found in high concentrations in the atmosphere.

* Smell: Ozone's pungent smell is often described as sharp, metallic, or even like chlorine bleach.

While ozone has some beneficial uses, like disinfecting water and air, it can be harmful to human health in high concentrations.