sunscreen protective factor index


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sunscreen protective factor index

In preparations for protecting the skin from the sun (using sunscreens), the ratio of the amount of exposure needed to produce a minimal erythematous response with the sunscreen in place divided by the amount of exposure required to produce the same reaction without the sunscreen. This index assesses the ability of sunscreens to block (short-wavelength) ultraviolet B rays but does not measure the protective effect of sunscreens against (long-wavelength) ultraviolet A radiation.
See: erythema dose
See also: index