A recent study found that sun protection is cumulative (to a degree). Participants applied SPF 30 sunscreen three times a day for five days. Those who used chemical (aka organic) sunscreens, like avobenzone and oxybenzone, were able to stay in the sun 50 percent longer than normal before they burned. The participants who used physical (aka mineral) sunscreens, like titanium and zinc oxide, were able to spend two-and-a-half times longer in the sun. Do take note, if you try the method: The effect only worked following five days of thrice-daily application, and this should boost your routine sunscreen coverage—not replace it.