Sun protection factor (SPF)
A number on a scale for rating sunscreens. SPF stands for Sun Protection Factor. SPF numbers on a package can range from as low as 2 to as high as 60. These numbers refer to the product’s ability to screen or block out the sun’s burning rays. The SPF rating is calculated by comparing the amount of time needed to produce a sunburn on protected skin to the amount of time needed to cause a sunburn on unprotected skin. Let us take for instance a fair-skinned person who would normally turn red after 10 minutes in the sun. Ten minutes is their "initial burning time." If that person uses a sunscreen with SPF 2, it takes 20 minutes in the sun for that person's skin to turn red. Now, if that person uses a sunscreen with SPF 15, it multiplies the initial burning time by 15, so it takes 150 minutes, or 2 and half hours, for that person's skin to turn red. Sunscreens with an SPF of 15 or higher are generally thought to provide useful protection from the sun's harmful rays.

Medical dictionary. 2011.

Look at other dictionaries:

  • Sun Protection Factor — SPF (Sun Protection Factor солнцезащитный фактор) основная характеристика солнцезащитных косметических средств, обозначает коэффициент, показывающий во сколько раз большее время потребуется коже защищённой солнцезащитным средством для получения… …   Википедия

  • SPF (sun protection factor) — A number on a scale for rating sunscreens. SPF stands for Sun Protection Factor. SPF numbers on a package can range from as low as 2 to as high as 60. These numbers refer to the product’s ability to screen or block out the sun’s burning rays. The …   Medical dictionary

  • sun protection factor — n spf * * * (SPF), sun protective factor the ratio between the number of minimal erythema doses required to induce erythema through a film of sunscreen and that for unprotected skin …   Medical dictionary

  • sun protection factor — noun the degree to which a sunscreen protects the skin from the direct rays of the sun • Syn: ↑SPF • Hypernyms: ↑degree, ↑grade, ↑level * * * noun : SPF herein * …   Useful english dictionary

  • sun protection factor — SPF. A scale for rating the level of sunburn protection in sunscreen products. The higher the SPF, the more sunburn protection it gives. Sunscreens with an SPF value of 2 through 11 give minimal protection against sunburns. Sunscreens with an SPF …   English dictionary of cancer terms

  • sun protection factor — sun′ protec tion fac tor n. pha See SPF • Etymology: 1975–80 …   From formal English to slang

  • sun protection factor — noun Date: 1978 a number assigned to a sunscreen that is the factor by which the time required for unprotected skin to become sunburned is increased when the sunscreen is used abbreviation SPF …   New Collegiate Dictionary

  • sun protection factor — number for measuring the level of protection of the skin against the suns rays, SPF …   English contemporary dictionary

  • sun protection factor. — See SPF. [1975 80] * * * …   Universalium

  • sun protection factor — noun → SPF …   Australian English dictionary

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