This article is from the Ozone Depletion: Stratospheric Chlorine and Bromine FAQ, by Robert Parson rparson@spot.colorado.edu with numerous contributions by others.
Vertical transport into and within the stratosphere is slow. It
takes more than 5 years for a CFC molecule released at sea level to
rise high enough in the stratosphere to be photolyzed. North-South
transport, in both troposphere and stratosphere, is faster - there is
a bottleneck in the tropics (it can take a year or two to get across
the equator) but there is still plenty of time. CFC's are distributed
almost uniformly as a function of latitude, with a gradient of ~10%
from Northern to Southern Hemispheres.
[Singh et al. 1979] [Elkins et al. 1993]
 
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