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UV (Ultra Violet) Radiation
Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV)
rays. Exposure to UV rays can cause numerous health problems, such as sunburn,
skin cancer, skin aging, cataracts, and can suppress the immune system. The
Vantage Pro2 helps analyze the changing levels of UV radiation and can advise of
situations where exposure is particularly unacceptable. UV radiation requires the
UV radiation sensor. The Vantage Pro2 displays UV readings in two scales: MEDs
and UV Index.
Note: Your station’s UV readings do not take into account UV reflected off snow, sand, or
water, which can significantly increase your exposure. Nor do your UV readings take
into account the dangers of prolonged UV exposure. The readings do not suggest
that any amount of exposure is safe or healthful. Do not use the Vantage Pro2 to
determine the amount of UV radiation to which you expose yourself. Scientific
evidence suggests that UV exposure should be avoided and that even low UV doses
can be harmful.
UV MEDs
MED (Minimum Erythemal Dose) is defined as the amount of sunlight exposure
necessary to induce a barely perceptible redness of the skin within 24 hours after
sun exposure. In other words, exposure to 1 MED will result in a reddening of the
skin. Because different skin types burn at different rates, 1 MED for persons with
very dark skin is different from 1 MED for persons with very light skin.
Both the U.S. Environmental Protection Agency (EPA) and Environment Canada
have developed skin type categories correlating characteristics of skin with rates of
sunburn.
T
ABLE
A-1: EPA S
KIN
P
HOTOTYPES
Skin Phototype Skin Color Tanning & Sunburn history
1 - Never tans,
always burns
Pale or milky white;
alabaster
Develops red sunburn; painful swelling,
skin peels
2 - Sometimes tans,
usually burns
Very light brown;
sometimes freckles
Usually burns, pinkish or red coloring
appears; can gradually develop light
brown tan
3 - Usually tans,
sometimes burns
Light tan; brown, or
olive; distinctly
pigmented
Rarely burns; shows moderately rapid
tanning response
4 - Always tans;
rarely burns
Brown, dark brown, or
black
Rarely burns; shows very rapid tanning
response