Explain the causes in the variations in the amount of ozone; natural and human caused.?

This question is really an earth science question, but I have some general information to get you going. Ozone is a thin protective layer of molecules made of three oxygens bonded together (O3). Aerosol sprays destroy this molecule, so in when humans use this spray, the ozone will become thinner. Humans control this by banning certain sprays from being sold and used.