The sun protection factor (SPF) of sunscreens is determined after application of a standard amount. The European Cosmetic Toiletry and Perfumery Association (COLIPA) standard amount is 2 mg/cm(2). Real-life application of sunscreen is probably less than this.
Centre for Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charité University Hospital, Berlin, Germany. juergen.lademann@charite.de
