[UV index and its implications].

The published UV index refers to the expected UV intensity at mid day, when the solar elevation is at its maximum. In Scandinavia, the maximum UV index is seven around midsummer. When the UV index is three, the erythema-weighted dose will be three Standard Erythema Dose (SED) in the hour with maximum intensity and nine SED in the three hours around solar noon, corresponding to 50% of the daily dose of 18 SED. A sun-sensitive Dane can tolerate two SED and an average Dane 4-5 SED before having erythema of the skin the next day. If outdoor all day without protection, they may therefore receive a sunburn already when the UV index is higher than two.