Quantity of ultraviolet radiation required to produce erythema: normal ranges in phototesting

This study evaluates whether expressing minimal erythema dose (MED) reference ranges in standard erythema dose (SED) units reduces variability caused by differing ultraviolet wavelengths in phototesting. Analysis of two nonphotosensitive population datasets demonstrated that converting MED from mJ cm−2 to SED substantially compresses interwaveband variation, producing reference ranges closely aligned with the original SED-defining study. These findings support the use of SED-based reference ranges to improve consistency across photodiagnostic services, while emphasizing the continued value of establishing local ranges tailored to specific equipment and populations.