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Compared To Outdoor Tanning...
INDOOR TANNING OFFERS CONTROL & COMFORT
Indoor tanners are at a great advantage by having access to the control and comfort that is part of the indoor tanning experience. In addition to various state and local regulations in place, national guidelines set by the Federal government enhance the controllable factors involved in indoor tanning. Since 1986, Federal Performance Standards for tanning devices have been in place to cover and control many of the following aspects of indoor tanning:
-Timer control
-Protective eyewear
-Temperature control
-Electrical safety
-Protection from lamps
-Equipment access and support, and more
VARIABLES INVOLVED IN OUTDOOR TANNING
Outdoor tanners are at the mercy of many uncontrolled elements. Here is an example of a few things to consider if tanning outdoors:
1. Solar elevation (height of the sun in the sky)
The intensity of outdoor ultraviolet light (the sun), and especially UVB, depends on the height of the sun in the sky. This will vary depending on the season of the year, time of day and latitude in which you live. UV intensities are highest during the summer months in the 4-hour period around noon (or 13:00 if daylight saving is in effect).
UVB intensity varies more with the time of the day than does UVA. As a rule of thumb "when your shadow is shorter than your own height" you may receive half or more of UVB during the 4 hours around solar noon on a clear summer day. In summer at noontime, UVB is two to three times more intense in equatorial areas than in northern Europe. At about 600 latitude the total UVB exposure during the months of January and February can be less than one clear day's exposure around midsummer.
2. Latitude and Altitude
The UV intensity at the earth's surface is related to the angle at which the UV rays pass through the atmosphere. In the tropics (close to 00 latitude, or near the equator) solar UV is more intense because it has less distance to travel through the atmosphere to the earth's surface.
UV intensities increase with altitude. This is because the amount of atmosphere available to absorb UV is reduced, and so more and shorter wavelength UV is able to reach higher altitude areas. In high altitudes, skiers can be exposed to higher intensities of UV, especially as snow is an excellent reflector.
3. Atmospheric Scattering
Solar UV is composed of direct and scattered radiation. The sky looks blue because the blue rays from sunlight are highly scattered by the atmosphere. UV is scattered even more than blue light, and this can lead to an increase in a person's exposure.
4. Clouds and Haze
UV intensities are highest under cloudless skies. Clouds generally reduce UV intensity, but light or thin clouds have little effect and under certain conditions may even enhance the UV intensity. Hazy days generally have higher amounts of water vapor; UV scatter in the atmosphere increases and can result in a higher personal UV exposure. Thus, even though haze or cloud cover can cause one to feel cooler, the UV exposure can still be high.
5. Ground reflection
The reflective properties of the ground have an influence on UV exposure. Most natural surfaces such as grass, soil and water reflect less than 10% of incident UV. However, fresh snow strongly reflects (80%) UV. During spring in higher altitudes, under clear skies, reflection from snow could increase UV exposure levels to those encountered during summer. Sand also reflects (10-25%) and can significantly increase UV exposure at the beach.
Reflected UV is a key source of exposure to the eye. Acute effects, such as snow-blindness while skiing or photokeratitis at the beach, can result from UV reflected from snow or sand respectively.
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