¥1989 Confirmation of ozone declines in
mid-latitudes of Northern Hemisphere
and in the Arctic
¥1990 Montreal Protocol
amended to require a complete phase out of all ozone depleting chemicals by 2000
¥1990 U.S.
requirement for recycling of CFCÕs
¥1992 Discovery of high levels of ClO
over middle and high latitudes of Northern
Hemisphere
¥1992 Further amendment of Montreal Protocol calling for an accelerated phase out by ozone depleting
chemicals
¥2100 Time
needed for ozone layer to heal completely?