Davis Instruments Vantage Pro2 manual Pro2 displays UV readings in two scales MEDs and UV Index

	from the sun and the reflected component from the rest of the sky. The
	solar radiation reading gives a measure of the amount of solar radiation hit-
	ting the solar radiation sensor at any given time, expressed in Watts/sq.
	meter (W/m2). Solar radiation requires the solar radiation sensor.
	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 evi-
	dence 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.

TABLE A-1: EPA SKIN PHOTOTYPES

Skin Phototype	Skin color	Tanning & Sunburn history
1 - Never tans,	Pale or milky white; ala-	Develops red sunburn; painful swelling, skin
always burns	baster	peels
2 - Sometimes tans,	Very light brown; some-	Usually burns, pinkish or red coloring appears;
usually burns	times freckles	can gradually develop light brown tan
3 - Usually tans,	Light tan; brown, or olive;	Rarely burns; shows moderately rapid tanning
sometimes burns	distinctly pigmented	response
4 - Always tans;	Brown, dark brown, or	Rarely burns; shows very rapid tanning re-
rarely burns	black	sponse

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