Sun protection factor
Sun Protection Factor (often abbreviated as SPF) is a measure of how well a sunscreen protects the skin from UVB rays, the kind of radiation that causes sunburn, damages skin, and can contribute to skin cancer.
Overview[edit | edit source]
The SPF rating is a measure of the time it would take for a person to sunburn if they were not wearing sunscreen, as opposed to the time it would take with sunscreen on. For example, "SPF 15" means that it would take 15 times longer for the skin to begin to burn with the sunscreen on than without it. However, this is a rough estimate that depends on skin type, intensity of sunlight, and amount of sunscreen used. SPF is actually a measure of protection from amount of UVB exposure and it is not meant to help you determine duration of exposure.
Calculation[edit | edit source]
The SPF is the ratio of the amount of light that induces redness in sunscreen-protected skin, following a sunburn, to the amount of light that induces redness in unprotected skin. As the SPF value increases, sunburn protection increases.
Limitations[edit | edit source]
While the SPF rating is a measure of UVB protection, it does not measure how well a sunscreen will protect from UVA rays. UVA rays are slightly less intense than UVB rays but they are 30 to 50 times more prevalent, and they penetrate the skin more deeply than UVB.
See also[edit | edit source]
| Sun protection factor Resources | |
|---|---|
|
 |
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
|
WikiMD's Wellness Encyclopedia |
| Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD
