The optimal application frequency and SPF of Sunscreen is going to differ drastically from person to person, place to place, all within a given year. A fresh-f

The optimal application frequency and SPF of Sunscreen is going to differ drastically from person to person, place to place, all within a given year. A fresh-faced Irish tourist will be burnt to a crisp after a 20 min stroll on the beach in QLD, Australia in January. Yet slathering on SPF 50 in rainy Dublin upon their return would be all but detrimental.