CFCs. What's the real truth?

[pethier@isd.net]

It is my understanding that CFCs have been banned as propellants and
refrigerants because they are supposed to harm the ozone layer.

I friend of mine insists that CFCs are heavier than air, and thus cannot
rise to the ozone layer.  His contention is that the whole thing was
dreamed up for political purposes.

So what is the truth here?  Are CFCs really heavier than air?

Phil Ethier