OXYGEN VS OZONE
Molecular oxygen (O2) is the normal oxygen that we breathe, present throughout the atmosphere. It can be split apart by the Sun’s rays into two single oxygen atoms, and one of these can then recombine with an O2 molecule to form O3 – ozone.
The gas has a distinctive and sharp odour, reminiscent of chlorine, and can sometimes be smelled after a thunderstorm, when lightning zaps oxygen molecules apart. This property is what gives ozone its name, after the Greek word ozein, meaning ‘to smell’.
The vast majority of ozone sits in the stratosphere. Ozone makes up roughly 0.00006 per cent of the atmosphere, and peak concentrations of it are present around 20 miles above the surface in an area known as the ozone layer. At that height, ozone absorbs intense ultraviolet radiation streaming in from the Sun.