Dr Bollmann, Skin Care Specialist, Anti-Aging Expert\nAll sunblocks are not created equal. A survey done several years ago reviewed hundreds of sun blocks, and found only eight (8) of them actually contained the ingredients they specified.\nThe climate where you live can affect the sunblock you use. For instance, I found that in Arizona, where I live, an SPF of 30 is not strong enough to prevent a burn. I use DNA Control Sun Block, available on our Bare Skin Care web site, which has an SPF of 40. If you have darker skin and live where the sun is less intense, you can get by with a 30 SPF, but why take the chance.\nAnd remember, sun blocks do not last more than two hours, when they must be reapplied. Also, things like sweating and water sports can decrease the effectiveness of sun blocks.\nSunburn most commonly happens between 10 am and 3 pm, when ultraviolet (UV) rays are at their strongest. Wear sunscreen with a sun protection factor (SPF) of 40 or greater, when you expect to be out in the sun for more than 15 minutes (a little sun is good for you). Ladies will also benefit by wearing facial makeup containing SPF. Sunlight can damage the sensitive cells of the macula (the central part of the eye that is responsible for most of our vision), so, be sure to wear sunglasses (pick shades that block 99% of UV-A and UV-B rays), and wear a wide-brim hat. Physical sun blocks like hats and clothing work, too.