Sun protection factor
The sun protection factor (SPF; Sun Protection Factor, SPF) is used to assess of sunscreens ( sunscreens ) in humans ( in vivo). It indicates how many times longer you can expose yourself with a sunscreen of sun without getting a sunburn, than would be possible with each individual self-protection time. The SPF is determined by the Colipa International Sun Protection Factor Test Method, whereby after standardized application of sunscreens increase skin redness threshold ( minimal erythema dose, MED) is determined.
Properties
By definition, is the light protection factor only to the protective effect of a product to the erythemal radiation. This is mainly the UV-B component of sunlight. To protect against other light- related skin damage sunscreen should also protect against UV -A radiation. Therefore, criteria are applied to the minimum activity against UV - B and UV -A radiation in sunscreens and in Europe since 2006:
- Sun Protection Factor (SPF): The sun protection factor of a sunscreen composition should be at least 6
- UV-A protection factor ( PF UVA ) of the UV -A protection factor of at least 1 /3 of the sun protection factor be
A sunscreen with an SPF of 30 is therefore have a UV-A protection factor ( PF UVA ) of at least 10. To test the UV -A protection factor a recommendation for the in vitro test was published by Colipa. Compliance with the required UVA protection is displayed on the packaging through a symbol. It consists of a circle containing the letters "UVA ".
After the definition of force today which used to be very popular sunscreen products with SPF 2 or 4 are no more sunscreen because they do not meet the predominant purpose ( = sun protection). For a better understanding is given on the packaging next to the sun protection factor still one of the 4 associated with protection classes ( Low, Medium, High, Very High ).
The sun protection factor is calculated from the measured values :
With the solar spectrum, the erythema action spectrum, the monochromatic protection factor, which are all dependent on the wavelength.
Product category / class → SPF / allowed data
Low → 6, 10 → means 15, 20, 25 High → 30, 50 → 50 Very High
The indication of the protection factors of the packages is limited by the predetermined values .
UV protection factor for textiles
Following the LSF for textiles the UV protection factor (USF ) or Ultraviolet Protection Factor (UPF ) specified, in accordance with the "Australian / New Zealand Standard 4399:1996 for sun protecting clothing evaluation and classification " ( AS/NZS4399: 1996 ) is calculated. A white t - shirt cotton has a UPF of about ten, that is, it leaves only a tenth of the UV radiation through. In wet or stretched state, or tight-fitting clothing in reduced protection against UV radiation. Clothing with a UPF > 15 meets the Australian / New Zealand Standard for sun protection, while the European Standard ( EN 13758-1999 ) will be fulfilled only from UPF 40.
In addition, concepts are developed, with which the protective effect of substances for visible wavelengths can be specified. Certain forms of sun intolerance ( porphyria, chronic actinic dermatitis, urticaria solaris ) and skin cancer patients treated with photodynamic therapy respond to the different visible wavelengths in sunlight. The protective effect of a substance to visible light can not be inferred from the UV protection factor.
History
In 1956, Rudolf Schulze the term protection factor of the sunscreen sun protection factor sunscreen. The Swiss chemist Franz Greiter, it defined the 1962 SPF.