Scientists were concerned about the loss of a minor constituent
from so high in the atmosphere because even in tiny
amounts, ozone filters out harmful solar UV radiation, preventing
it from reaching Earth’s surface. They predicted that
the continuing removal of ozone from the high atmosphere
could cause trouble for terrestrial life as more and more UV
radiation reaches the ground. Measured increases in the levels
of UV radiation appear to be related to increases in skin
cancer in humans, and the mutating effects it may have on
other life-forms are not yet understood. By the late 1980s,
international agreements on phasing out the production of
CFCs and other ozone-depleting chemicals were signed, and
world consumption has steadily declined. The largest Southern
Hemisphere ozone hole occurred over Antarctica in 2006;
the largest Arctic hole so far happened in 2011. Full recovery
is not expected until the late 21st century at the earliest.