Review highlights reduced effectiveness of SPF 50 sunscreen at typical application levels, suggesting improved application methods for better protection.
Sunscreen is the most common way of protecting the skin against ultraviolet radiation damage from the sun. The Danish Health Authorities recommends using at least sun protection factor (SPF) 30 in Denmark. The SPF indicates how much the UV dose is reduced when 2 mg/cm2 sunscreen is applied to the skin. The average Dane uses only a fourth of the recommended amount, resulting in a SPF 50 providing a real SPF of only 2.6 (Fourth root of 50). To obtain optimal sun protection, increased layer thickness is of crucial importance, which is why this review recommends applying sunscreen twice in the morning before sun exposure.
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Hans Christian Wulf (2025) studied this question.
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