Frequently Asked Questions
What is an MED?
A MED is a minimal erythemal dose, i.e. the amount of erythemal UV that is needed to produce a just-perceptible reddening of the skin (very mild sunburn). The MED varies from person to person - some fair skinned people burn very easily (low MED) while someone with naturally pigmented skin would have a much higher MED.
Pigmented skin naturally contains melanin, which gives it its brown colour. Melanin absorbs UV radiation and therefore protects the skin underneath.
An individual MED is measured on unexposed skin because with exposure to UV the skin can adapt by thickening and also by tanning (developing additional melanin) to provide some protection. Frequently exposed skin may then burn less easily.
Typical MEDs are often associated with different skin types, but it should be noted that a wide range of MEDs can apply to one skin type, since skin types are broad classifications and human beings are infinitely variable individuals.