¥CFCs stay in atmosphere for
~100 years
¥ One
freed chlorine atom destroys thousands of O3 molecules
before leaving stratosphere
¥Montreal Protocol mandated total
phase out of ozone depleting substances by 2000.
¥Even with a complete phase
out, O3 levels
¥ Would
not increase for another 10-20 years
¥ Would not
completely recover for ~100 years