Yes, they do. They have known it by experiments.
Ozone layer contains ozone in it. Therefore, it is named so.
ozone layer in Tagalog: ozone layer (no direct Tagalog translation)
It will have zero effect. The ozone layer is affected by water vapor, the amount of sunshine and (according to some) CFC's which are produced during the creation of your air conditioner or refrigerator. Recycling is a great idea, but will have zero effect on the ozone layer.
Ozone layer is formed of ozone. It is a gas.
Earth has a layer of ozone. It is present as the ozone layer.
damage to ozone layer is called ozone depletion. It is thinning of ozone layer.
Scientists notices the UV rays. It gave them the idea about the ozone hole.
Scientists collect the ozone concentration. This gives them an idea to check the thinning.
The layer of gases that surround the atmosphere is ozone. It is present as the ozone layer.
The ozone layer is in the stratosphere. It is a pool of ozone molecules.
Ozone layer is the layer of ozone. Humans are altering it by CFC's.
Earth and Venus have a protective ozone layer. These planets have ozone molecules in ozone layer.