SUNSCREEN IS SUPPOSED TO prevent sunburns—but research shows it might also cover them up. It all started with a scorched guinea pig. Eugene Pittz, a chemist in New Jersey was formulating sunscreens for the cosmetics company Warner-Lambert (now a part of Pfizer) in the early '80s when he accidentally gave one of his laboratory animals too much ultraviolet radiation. He applied sunscreen to the burn, and to his surprise, the rodent's redness faded. He ran a few more experiments (including one on himself) and confirmed that the now ubiquitous UVA blocker oxybenzone had anti-inflammatory properties. Pittz patented his findings, but sunscreen makers haven't been in a rush to publicize them. Understandably so: If your sunscreen makes your sunburn look less severe, you're likely to spend more time in the sun without realizing you're slowly roasting.