Two Consecutive Sunscreen Applications Optimize Sun Protection

The investigators aim to investigate how much two consecutive applications of sunscreen before sun exposure can increase the quantities of sunscreen applied and decrease the skin area left without sunscreen compared to a single application. Volunteers wearing swimwear applied sunscreen in a laboratory environment twice and had pictures taken in black light before and after. As sunscreens absorb black light the darkness of the skin increased with increasing amounts of sunscreen applied. The investigators conducted a standard curve establishing a link between picture darkness and applied sunscreen quantity. Participants were asked to apply sunscreen the way they would normally do but two consecutive times. No other advice was given. The level of protection was determined by picture analysis as measurements of darkness of selected skin sites as well as the percentages of skin area left without sunscreen in different body regions and in total.