Question: why do we have an o zone layer

Joanne Duffy answered on 7 Nov 2017:

So, you know that oxygen exists in the form O2. That just means that two oxygen atoms are bonded together, and that’s the way oxygen is chemically happy. Well, if you hit a molecule of O2 with UV light, it splits into two individual atoms of oxygen (Just O). One of those free oxygens can then bind to another molecule of O2, and you get, you guessed it, O3. O3 is ozone. Lots of this hangs around in a special later of the stratosphere, and it prevents damaging radiation from sun getting down to earth. That’s why it’s a big worry when we do damage to the ozone layer. There was a massive “hole” in it, but we’ve done very well at repairing this damage, by being more environmentally conscious.