# 17-26-074

sun protection factor

SPF

FSP

factor describing the protective quality of a sunscreen against solar ultraviolet radiation, normally determined by in vivo testing

Note 1 to entry: The sun protection factor is usually determined by comparing the dose of ultraviolet radiation from a solar simulator (often a xenon lamp) required to produce just-perceptible actinic erythema approximately 24 h after exposure in ultraviolet-irradiated human volunteers, with and without a standard amount of the sunscreen being present (FMED,f and FMED,i, respectively) and is calculated as follows:
FSP = FMED,f / FMED,i.

Note 2 to entry: The sun protection factor can also be determined by equivalent in vitro methods.

Note 3 to entry: The sun protection factor has unit one.

Note 4 to entry: This entry was numbered 17-1278 and 17-1243 in CIE S 017:2011.

Publication date: 2020-12