I’m really not trying to be a smartass.
Chlorofluorocarbons are made of chlorine, fluorine and carbon. All of which are many time more heavy than either oxygen or nitrogen, but I’m supposed to believe it floats to the stratosphere. This does not make sense (Johnnie Cochran voice)!
Fine DUST will remain in the stratisphere for years, if it gets there.
Have you heard of Brownian Motion?
Besides, the problem is that Freon (with help from the sun) reacts with ozone (O3), destroying it.