Question

What emissions from human activities lead to ozone depletion? And what are the principle steps in stratospheric ozone depletion caused by human activities?

Answer 1

Ozone depletion is caused due to the CFCs and other such depleters.
$O_3+\stackrel{\bullet }{Cl}⟶Cl\stackrel{\bullet }{O}+O_2$
CFCs convert ozone to oxygen molecules. Principal steps in ozone depletion are emission of CFCs, then reaching the stratosphere and then depletion of layer.