Determination of solar ultraviolet dose in the Dead Sea treatment of psoriasis.

Background: An increased risk of developing cancer of the skin is the only potentially serious (albeit unproven) long-term side effect of heliotherapy and it is therefore prudent to avoid unnecessary exposure to solar ultraviolet radiation. Traditional heliotherapy for psoriasis at the Dead Sea calls for a sun exposure of 5-6 hours daily for 28 days. Studies have determined that mid-summer exposure for 3 hours is equally effective.