No matter how hard some of us try to be vigilant with sunscreen, it’s still easy to end up burned, red or more exposed than we intended on long vacation days spent under the sun.
Researchers at the Department of Dermatology at Denmark’s Bispebjerg Hospital in Copenhagen applied SPF 30 sunscreen to subjects three times a day for five consecutive days. Those who used chemical sunscreen (like avobenzone and oxybenzone, that are, in chemistry-speak, confusingly known as organic sunscreens) were found to have an extra SPF 1.56 more than normal. Those who used physical-blocking mineral sunscreen (like titanium and zinc oxide, known as particle sunscreens) experienced an SPF 2.45 increase.
READ MORE: Non-Sunscreen Ways to Protect Your Skin From the Sun
What does that mean? If, for example, you’re usually able to stay in the sun an hour before burning, then the chemcial sunscreen regimen would protect you for an hour and a half before burning, while the mineral sunscreen method would protect you for two and a half hours before burning.
Sorry short-cutters: Applying either sunscreen only once daily over five days did not result in an accumulation.
“This is an exciting study—it’s not a substitute for wearing sunscreen, but it acts like an insurance policy, so if your sunscreen rubs off or if you miss a spot on the beach, you have more time to catch it before getting a burn,” says Maryland dermatologist Noelle S. Sherber, M.D., who now recommends pre-vacation SPF application to her patients.
Sherber suggests applying sunscreen in the morning, reapplying once on exposed areas during the day (a brush-on mineral sunscreen powder may be easiest if you’re wearing makeup), and then applying at bedtime. “I don’t usually advocate people wearing SPF-containing products overnight, but I do recommend it for five days before a sunny vacation because it’s a great way to get additional protection in,” she says.
READ MORE: Our Top Sunscreen Picks