All of them.
Be really good to know what you intended to ask. Are you wanting to know "what ppm is in the ozone layer", "what is ozone used for", or something different. See the related questions section below.
The ozone issue has changed with time. The use of CFC first depleted the ozone but now it is stable.
No humans don't cause the ozone layer, however some of the chemicals we use is causing parts of this layer to disappear.
There can be many solutions for ozone depletion. Some of it are afforestation, use of HCFC's etc.
We use many products that are harmful to ozone. Deodorants, Fridges, Sprays etc are all here.
Arosol hairspray can contribute to ozone layer depletion if it contains chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful chemicals known to break down ozone molecules. However, many hairsprays now use alternative propellants that are less harmful to the ozone layer. Check the ingredients list to ensure the product is ozone-friendly.
They use hydrocarbons now; they used to use chlorofluorocarbons (CFC's) which were damaging to the ozone layer.
It is because the extent of damage is very large. Moreover small use of ODS can also cause destruction.
Countries can help the ozone layer in many ways. they can set regulations on the use of CFC's.
The ozone problem start with the use of CFC's. They react with ozone.
To save ozone, curb the use of CFC's. they deplete ozone.
Chlorofluorocarbons have been banned from use as aerosols as well as many other ozone depleting chemicals.
There is many different types of Freon. If the freon that you are trying to use is R-22 then you have to have a EPA certification to handle that freon. This freon is considered ozone depleteing. Now there is freon out there that is not ozone depleting like the freon in cars made after 1993. That is called R-134a which is sold everywhere even in Wal-Mart.