Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

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Environmental Impact
RADIATION FROM THE SUN
UV-B
Figure 1.2. Radiation from the sun
DONE
UV-A
OZONE LAYER
EARTH
UV rays are dangerous to human beings,
animals and plants because they burn. They
can penetrate our skin and eyes and weaken
our bodies’ immune system. That is why we
should avoid long periods in the sun. To get
the minimum daily dose of vitamin D only 15
minutes in the sun per day is enough. If we
stay more than that, we might get sunburnt if
no protection is used. Repeated sunburns and
frequent tanning can cause premature ageing
of the skin and, at worst, skin cancer such as
melanoma (because of UV-A and UV-B). For
the eyes the UV-B rays can cause a cataract
(clouding of the eye lens). Most of the serious
health problems appear only many years later.
CATEGORY WAVELENGTHS
(nanometres)
REACTIONS IN &
WITH
STRATOSPHERE
UV-A: 315/320 - 400 nm Not significantly
absorbed by the
stratospheric ozone
layer.
UV-B: 280 – 315/320 nm Absorbed by ozone
in the stratosphere.
Ozone absorbs UV
radiation without
being reduced; the
overall result being
to convert UV
radiation to heat.
UV-C: 200 - 280 nm Highly absorbed by
oxygen molecules:
involved with
formation of ozone.
EFFECT UPON
HUMANS, PLANTS ETC.
10-15% of ‘burning’:
possible connection with
the formation of skin
cancers. Responsible for
'tanning' & skin ageing.
85 – 90 % ‘burning’;
involved with both
malignant & benign
cancerous growths. Also
linked to eye cataracts.
Effects on growth of plants
and marine life. Strong
radiation kills also plankton
in the water which is the
main food supply for
fishes.
Not thought to be
significant, mainly because
of its efficient absorption
at high-altitudes.
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