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Facts
about ultraviolet radiation and precautions
The
sun gives out tremendous energy in the form of
radiation. This energy is related to the wavelength of
radiation which is measured in nanometers (nms).
X-rays, Gamma rays, microwaves, radio waves,
ultraviolet rays are the types of radiation.
Ultraviolet radiation is made up of UVA,UVB and UVC.
UVA has the longest rays and UVC has the shortest. The
deadliest UVC are either absorbed in space or in the
ozone layer. Some UVB and most UVA reaches the earth
surface. When people are exposed to UVB it causes
sunburn and produces melanin which gives them a tan.
It also damages DNA in the skin which causes skin
cancer. UVB damages the skin, causing wrinkling,
sagging and premature aging.
The Ultraviolet
Index :
UV
Index ranks the UV radiation levels and risks for
human health. The UV index is approved and recommended
by World Health Organization (WHO).The index predicts
UV intensity levels on the scale of 0 to 10+, where 0
indicates a minimal risk of overexposure and 10+ means
a very high risks of solar UV intensity variations :
|
UV I
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0~2
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3~4
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5~6
|
7~9
|
10+
|
|
DANGER
|
Minimal
|
Low
|
Moderate
|
High
|
Very High
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To
check daily UV level and prediction please check at
EPA web site http://www.epa.com
Ultraviolet
Protection Factor (UPF) :
This
is the way clothing is rated in the new
AS/NZS4399-1996 standard for the sun protection
clothing. The Australian Radiation Laboratory have
proposed the following UV protection rating scheme :
|
UPF
|
Mean effective
UVTransmission
|
Protection
Category
|
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UPF 10~19
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10%~5.1%
|
Moderate
Protection
|
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UPF 20~29
|
5%~3.4%
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High Protection
|
|
UPF 30~49
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3.3% ~2%
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Very High
Protection
|
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UPF50+
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Less than 2%
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Maximum
Protection
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The Skin Types :
The
natural protection of human skin (approximate safe
period in the sun) depends on skin type. Human skin
type is divided into 6 types, of which Type 1 has
shortest natural protection period and Type 6 the
longest.
|
TYPE
|
Features
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Reaction
of the skin**
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Natural
protection time of skin
|
|
I
|
Fair skin ,fair
hair ,blue eyes
|
Always sunburn
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5~10 minutes
|
|
II
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Light skin, fair
hair, green eyes
|
Always sunburn
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10~20 minutes
|
|
III
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Light skin,dark
hair,browneyes
|
Light sunburn
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20~30 minutes
|
|
IV
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Dark skin, brown
hair/eyes
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No sunburn
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Approx. 45
minutes
|
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V
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Dark skin, black
hair/eyes
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No sunburn
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Approx. 60
minutes
|
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VI
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Black skin, Black
hair/eyes
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No sunburn
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Approx. 90
minutes
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**
Reaction of unprotected skin to 30 minutes of sun
shine in midday sun of summer.
Precautions :
By
taking a few simple precautions, you can greatly
reduce your risk of sun related illnesses. To be sun
wise consider following steps :
#
Limit your time in the sun between 10 a.m. and 4 p.m.
# Whenever possible seek shade.
# Wear full length UV protection clothing with
certified UPF rating.
# Wear wide brimmed hat, sun screen and UV-protective
sun glasses.
# Avoid sun tanning.
# Watch for
UV index daily.
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