Editor's note: This article is especially relevant for the Humid Subtropical, Savanna, Steppe, Monsoon, and Karst skin types.
Similar results were found in another study involving beachgoers. There was an increase in the amount of sunscreen used after double application except for the upper back, which is usually a spot that it hard to reach. After a single application, around 20% of the skin was missed, but this percentage was halved after another layer of sunscreen was applied.