Now that longer days and warmer temperatures are coaxing people outdoors, it’s time to buy this season’s bottle of sunscreen. But a recent industry study suggests that people aren’t sure what to look for when choosing a sunscreen. Many don’t understand the difference between UVA and UVB (which are types of ultraviolet light) and are confused about what “sun protection factor,” or SPF, really means.
The American Medical Association and the American Academy of Dermatology recommend using a broad-spectrum sunscreen (which means it shields against both UVB and UVA rays). They also recommend an SPF of at least 15.
The sun emits both UVA and UVB radiation. UVA rays, the so-called “tanning rays,” are emitted by most sun lamps. Previously, only UVB radiation, which causes sunburn, was thought to be harmful. Some sunscreens protect only against UVB radiation. But recent research has linked UVA rays with malignant melanoma, the most deadly form of skin cancer.
As for SPF, a higher number doesn’t indicate a higher degree of UV protection, as some people believe. Higher numbers offer protection for a longer period of time. But the actual time you’re burn-free depends upon your skin type. If you sit outside at midday and your skin reddens in 20 minutes without sunscreen, putting on an SPF 15 sunscreen beforehand would make it possible to sit out 15 times longer (about five hours) before burning. If you have very fair skin, you might burn in less than 20 minutes and so the same sunscreen would protect you for less time; if your skin is dark, you’ll probably take longer to burn.
Apply sunscreen 15 to 30 minutes before going outdoors, and don’t skimp on the amount, experts advise. An average-size person should use about 2 tablespoons per application, which should be repeated according to the manufacturer’s directions.
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