2006-10-29 14:12:21 · 7 answers · asked by Anonymous in Health ➔ Other - Health
SPF stands for Sun Protection Factor. The number is determined experimentally indoors by exposing human subjects to a light spectrum meant to mimic noontime sun. Some subjects wear sunscreen and others do not. The amount of light that induces redness in sunscreen-protected skin, divided by the amount of light that induces redness in unprotected skin is the SPF. It is mainly a measure of UVB protection and ranges from 1 to 45 or above.
A sunscreen with an SPF of 15 filters 92% of the UVB. Put another way, a sunscreen with an SPF of 15 will delay the onset of a sunburn in a person who would otherwise burn in 10 minutes to burn in 150 minutes. The SPF 15 sunscreen allows a person to stay out in the sun 15 times longer.Sunscreens with an SPF of 15 or higher are generally thought to provide useful protection from the sun's harmful rays. SPF does not predict UVA protection.
The "protectiveness" of clothing can also be measured by SPF. The following are SPF's of various types of clothing:
>Nylon Stockings - SPF 2
>Hats - SPF 3-6
>Summer-weight clothing - SPF 6.5
>Sun-protective clothing - up to SPF 30♥
2006-10-30 15:41:38 · answer #1 · answered by ♥ lani s 7 · 1⤊ 1⤋
SPF, an abbreviation for sun-protection factor, is a number such as 15, 30 or 50 that indicates how long a topical sunscreen remains effective on the skin. A user can determine the duration of effectiveness simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen.
For example, Mary A. normally suffers a burn in 10 minutes without wearing a sunscreen. If she applies a sunscreen with an SPF of 15, she will be protected for 150 minutes (10 minutes multiplied by the SPF of 15). As another example, Jack B. normally burns in a half-hour without wearing a sunscreen. If he also applies a sunscreen with an SPF of 15, he will be protected for 450 minutes (30 minutes multiplied by the SPF of 15).
2006-10-29 22:23:53 · answer #2 · answered by absolutelyfab 1 · 4⤊ 0⤋
Sun Protection Factor
2006-10-29 22:16:51 · answer #3 · answered by gtarhal2@sbcglobal.net 1 · 0⤊ 1⤋
It is used in sunblock or sunscreen descriptions, and stands for "Sun Protection Factor." The higher the SPF factor, more protection it provides. If sun protection is a concern for you (it should be, for almost everyone), also look for sunscreens/blocks that provide ultraviolet ray protection, listed as UVA and/or UVB for the type of ultraviolet from which it protects.
2006-10-29 22:22:59 · answer #4 · answered by Sher 3 · 2⤊ 0⤋
Sun (or Solar) Protection Factor
2006-10-29 22:14:08 · answer #5 · answered by Anonymous · 0⤊ 1⤋
Sun protection factor
2006-10-29 22:14:44 · answer #6 · answered by RBRN 5 · 0⤊ 1⤋
Um, sun protection factor???
2006-10-29 22:14:29 · answer #7 · answered by Oghma Gem 6 · 0⤊ 1⤋