Environmental Engineering Reference
In-Depth Information
McKenzie 1992). Since the Antarctic ozone hole
extends over the southern continents at the end
of spring, the higher levels of ultraviolet radiation
are probably associated with the thinner ozone
at that time. However, that in itself is considered
insufficient to explain the high rates of skin
cancer. Epidemiologists continue to place most
of the blame on social factors which encourage
over-exposure to ultraviolet light, rather than on
ozone thinning. The consensus among
researchers is that the latter will only begin to
contribute to skin cancer statistics in the second
half of the 1990s (Concar 1992). To counter this,
both the Australian and New Zealand
governments have initiated campaigns to
discourage exposure to the sun, by advocating
the use of sunscreen lotions and wide-brimmed
hats and by promoting a variety of behavioural
changes that would keep people out of the sun
during the high risk period around solar noon
(Concar 1992; Seckmeyer and McKenzie 1992).
A similar approach is being developed in Canada,
but in the northern hemisphere concern over the
dangers of excess ultraviolet radiation generally
lags behind that in the south.
The attention paid to skin cancer has caused
other effects to be overshadowed. Radiation,
blindness and cataracts were early identified as
potential problems (Dotto and Schiff 1978).
More recently, damage to the human immune
system has been postulated, and there is some
evidence that ultraviolet light may be capable of
activating the AIDS virus (Valerie
et al.
1988).
Concentration on the direct effects of ozone
Figure 6.8
Schematic
representation of
the radiation and
temperature
changes
accompanying the
depletion of
stratosphere
ozone
