Sunlight has long been thought to be the cause of premature skin aging, and skin cancer. UV radiation is the actual in culprit. There are 3 types of UV radiations; UVC 160-290nm, UVB 290-320nm, and UNA 320-400nm. UV rays cause free radicals. Free radicals are unstable O2 molecules that have one electron instead of 2. They are negatively changed. Electrons are found in pairs so a free radical is always trying to steal an electron from another molecule. This causes a domino effect. This process damages cellular function and alters genetic material. Free radicals cause wrinkles by activating metalloproteinase which breaks down collagen. They cause cancer by charging genetic material such as RNA and DNA.
We have developed sunblock and sunscreens to protect our skin. Although we often use the two terms interchangeably, they work by entirely different mechanisms. Sunscreens interact with ultraviolet light on your skins surface and inactivate it in a chemical reaction. Sunblock prevents the damaging rays from ever reaching the skin.
UVB is the culprit behind sunburns, while UVA, which penetrates more deeply, is associated with wrinkles and other damages of photo aging. UVC is a more recent designation of Ultaviolet rays that are becoming more of a consideration. The ozone layer stops UVC rays from getting thru, as the ozone layer becomes thinner UVC rays become more of a consideration. Exposure to UVB rays is all that is being considered when products are labeled with a certain SPF. Here is how it works. If it takes 20 minutes for unprotected skin to turn red, a product labeled with an SPF of say, 15 would theoretically prevent reddening 15x longer or it would take about 5 hours in the sun to have the same effect as twenty minutes in the case of unprotected skin. Another way of looking at it is in terms of percentage. SPF 15 blocks rays 93 percent all incoming UVB rays, SPF 30-97%, and SPF 5-98% of UVB rays.
Now that we know all this info how do we use it to choose the best sunblocks and sunscreens? Ideally you want a total block, one that blocks UVAB&C. I like blocks rather than screens because with sunscreens, the UV light is getting to the skin and then being inactivated. I think it is best not to ever let damaging rays to ever reach the skin. This is what sunblocks do. They act as a physical barrier. The new sunblock’s are micronized so they can effectively work as a block without making you look “white”.
All sunblocks or sunscreens must be applied every two hours to be considered effective. The correct amount must be used. A full teaspoon is the amount that is suggested on the face if one is to achieve the results of the SPF on the label.
In our office we like Tizo which is made by a company called Total Block. Not only does TIZo block UVA, B&C rays, it also contains multiple antioxidants such as vitamin C. These antioxidants counteract free radical damage that is caused by the few rays that do get through.
There has been suggestions that the entire SPF is antiquated and a new labeling be instituted that address the level of protection from UVA, UVB, and UVC, as well have a star system to reflect the concentration of antioxidants. Until these changes however it is best that the consumer be knowledgeable not only on what they are purchasing but also how to use it correctly.