Sunscreen protects the skin from UV radiation from the sun. There are many sunscreen products available. The SPF number 15, 30, 45 tells how long the sunscreen is effective upon application. It is very important to apply sunscreen liberally and to reapply every two hours or sooner if exercising or swimming. Sunscreen should also be applied 30 minutes before going outside. To protect your skin from sun damage, it is important to apply a sunscreen with an SPF of 30 or greater, one that protects against both UVA and UVB radiation, and contains at least 5% zinc oxide in the ingredients. Blue Lizard sunscreen is ranked the #1 sun protection product. Blue Lizard promotes healthy skin and reduces skin cancers.