Sun protection factor

The sun protection factor ( SPF ; English sun protection factor , SPF ) is used for evaluation of sunscreens ( sunscreens ) in humans ( in vivo ). It indicates how much longer you can expose yourself to the sun with a sunscreen product without getting sunburn than is possible with the individual self-protection time. The SPF is determined according to the COLIPA International Sun Protection Factor Test Method , whereby the increase in the skin reddening threshold ( minimum erythema dose , MED) is determined after standardized application of sun protection preparations .

properties

According to the definition, the sun protection factor only indicates the protective effect of a product against erythema-causing radiation. This is mainly the UV-B part of the sunlight. To protect against other light-induced skin damage, sunscreens must also protect against UV-A radiation. Therefore, criteria for the minimum effectiveness against UV-B and UV-A radiation have been applied to sunscreen products in Europe since 2006:

• Sun protection factor (SPF): The sun protection factor of a sunscreen should be at least 6
• UV-A protection factor (UV-A-PF): The UV-A protection factor must be at least one third of the sun protection factor

A sunscreen with an SPF of 30 should therefore have a UV-A protection factor (UV-A-PF) of at least 10. To test the UV-A protection factor, COLIPA issued a recommendation for in vitro testing. Compliance with the required UVA protection is indicated on the packaging by a symbol. It consists of a circle containing the letter combination "UVA".

According to the definition that is valid today, the sun protection products with protection factor 2 or 4, which used to be very popular, are no longer sun protection products because they do not fulfill the main purpose (= sun protection). For a better understanding, one of the four assigned protection classes is indicated on the packaging in addition to the sun protection factor (low, medium, high, very high).

The sun protection factor is calculated on the basis of measured values ​​for UV radiation between 290 and 400 nm :

${\displaystyle \mathrm {LSF} ={\frac {\int A(\lambda )E(\lambda )d\lambda }{\int A(\lambda )E(\lambda )T(\lambda )d\lambda }},}$

with the solar spectrum , the erythema effect spectrum and the transmission in percent, all of which are dependent on the wavelength . ${\displaystyle E(\lambda )}$ ${\displaystyle A(\lambda )}$ ${\displaystyle T(\lambda )}$ ${\displaystyle \lambda }$

Product category / protection class → sun protection factor / permitted information

• low → 6, 10
• medium → 15, 20, 25
• high → 30, 50
• very high → 50+

The information on the sun protection factors on the packaging is limited to the specified values.

UV protection factor for textiles

Based on the SPF, the UV protection factor (USF) or ultraviolet protection factor (UPF) is specified for textiles, which is calculated according to the Australian / New Zealand Standard 4399: 1996 for sun protecting clothing evaluation and classification (AS / NZS4399: 1996) becomes. A white cotton T-shirt has a UPF of around ten, which means it lets through a tenth of the UV radiation. This protection is reduced even more when the clothes are wet or stretched or when the clothes are tight-fitting. Clothing with a UPF> 15 meets the Australian / New Zealand standard for sun protection , while the European standard (EN 13758-1999) is only met 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 ( porphyrias , chronic actinic dermatitis , solar urticaria ) and skin cancer patients treated with photodynamic therapy react to the various visible wavelengths in sunlight. The protective effect of a substance against visible light cannot be inferred from the UV protection factor.

history

In 1956 Rudolf Schulze introduced the term protection factor for sun protection agents , the sun protection factor for sun protection agents . The Austrian chemist Franz Greiter defined the sun protection factor from this in 1962 .

Web links

Wiktionary: Sun protection factor  - explanations of meanings, word origins, synonyms, translations

Individual evidence

1. ↑ COLIPA: International Sun Protection Factor (SPF) Test Method, 2006. ( PDF, 1.3 MB  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and remove it then this note. )  
2. ↑ U. Osterwalder, B. Herzog: Sun protection factors: world wide confusion . In: British Journal of Dermatology . 161 vol., Special edition no. S3, November 2009, doi: 10.1111 / j.1365-2133.2009.09506.x , pp. 13-24.
3. ↑ AS / NZS 4399: 1996 Sun protective clothing evaluation and classification. (PDF; 120 kB) July 5, 1996, accessed September 25, 2010 .  
4. ↑ FLUGS: UV protection through textiles. ( Memento of the original from June 26, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. PDF, 267 kB 
5. ↑ C. Van den Keybus, J. Laperre, R. Roelandts: Protection from visible light by commonly used textiles is not predicted by ultraviolet protection. In: Journal of the American Academy of Dermatology Volume 54, Number 1, January 2006, pp. 86-93, ISSN  1097-6787 . doi: 10.1016 / j.jaad.2005.08.059 . PMID 16384761 .
6. ^ Urbach F. (1991): Franz Greiter - The Man and His Work. In: Riklis E. (eds) Photobiology. Springer, Boston, MA. doi : 10.1007 / 978-1-4615-3732-8_82

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !