Shopping for skin products that offer protection from the sun can be confusing. And labels that feature superlatives — such as total sunblock, waterproof, all-day protection and deep-tanning — provide little solid information for those seeking the best protection for their skin type.
Sun protection factor (SPF) ratings refer only to UVB protection. It’s important to check sunscreen labels to ensure that the product is a broad-spectrum sunscreen. Products containing zinc oxide or titanium dioxide are among those that provide protection against both UVA and UVB.
SPF ratings are based on how much longer someone may be protected from sunburn than he or she is if no sunscreen were applied. For instance, if you normally burn in 20 minutes, a product with SPF 15 will allow you to stay out in the sun 15 times longer. You’ll be able to stay out in the sun without burning for five hours, assuming you applied the sunscreen properly. The SPF number doesn’t refer to a sunscreen’s strength. For example, an SPF 30 is no stronger than an SPF 8 — it doesn’t filter out more harmful rays than an SPF 8 does — but it does protect you longer.
(Source: Mayo Clinic, online at www.mayoclinic.com.)>