![]() SPF 15 will prevent about 94% of the sun's harmful rays from hitting your skin, and will only do so for about 2 hours. It's easy to think that SPF 30 provides twice as much coverage for twice as long or that SPF 100 will wrap you in a cloak of invincibility and perpetual youth. You've probably seen SPF, 15, 30, 50, 100, and so on. Note here there is nothing mentioned about UVA protection. Also, “because SPF values are determined from a test that measures protection against sunburn caused by UVB radiation, SPF values only indicate a sunscreen's UVB protection.” In short, SPF tells you how long you could potentially stay in the sun without getting a sunburn. According to the FDA, SPF measures how much UV radiation it takes to burn protected skin, relative to the amount of UV radiation required to burn on unprotected skin. Regardless of the sunscreen formulation, each sunscreen has a Sun Protection Factor, SPF. The instability and degradation rate of the UV filter is why it’s necessary to reapply sunscreens as directed.ĪBOUT SUN PROTECTION FACTOR (SPF) RATINGS They are often combined with ingredients to help stabilize them as well as Avobenzone in order to provide broad-spectrum UV protection. Homosalate, Octisalate, Octinoxate, all filter UVB rays and are also unstable. Research shows that when stabilized and paired with Zinc Oxide it provides better protection than when it’s paired with Titanium Dioxide. It is the most used UVA filter in the world. Avobenzone filters UVA rays but is highly unstable and breaks down easily when exposed to light. Zinc Oxide and Titanium Dioxide are stable (don’t break down in UV light) and provide broad-spectrum protection on their own, though both may be too white/chalky for use on dark skin. While not yet mandatory, many brands market their products as being broad spectrum. The FDA is still working on a proposal to make it mandatory for approved sunscreens with SPF 15 or greater to be broad-spectrum. Sunscreens that provide protection from both UVA and UVB rays, (all wavelengths) are referred to as broad-spectrum. UV Rays are present rain or shine, snow or sleet. Approximately 95% of the UV rays that reach the earth’s surface are UVA rays, with the other 5% being UVB Rays. To help us remember which is which, we often refer to UVA as the aging rays, and UVB as the burning rays. They are also thought to cause most skin cancers. They can damage the DNA in skin cells directly, and are the main rays that cause sunburns. UVB rays have slightly more energy than UVA rays. UVA rays are mainly linked to long-term skin damage such as wrinkles, but they are also thought to play a role in some skin cancers. These rays can cause skin cells to age and can cause some indirect damage to cells’ DNA. UVA rays have the least energy among UV rays. Not all sunscreen ingredients protect from both UVA and UVB rays. You might be wondering, why do sunscreens use a combination of sunscreen ingredients? Well, that's a good question. That combination of micronized particles from physical sunscreens and chemical sunscreen ingredients can be the basis for a sunscreen product for dark, sensitive skin. The smaller the particles of the Titanium Dioxide and Zinc Oxide, the more sheer the formula. There are also hybrid sunscreen formulas that contain micronized physical blockers, along with some chemical ingredients. The FDA has a proposal out for more research on these ingredients. There is evidence that UV filters are absorbed in the body though it is not yet clear how these ingredients affect us. Ingredients include ensulizole, octisalate, homosalate, octocrylene, octinoxate, oxybenzone, Avobenzone, Cinoxate, dioxybenzone, meradimate, padimate O, sulisobenzone. It also includes the percentage of each ingredient that can make up the final product. The FDA has a list of chemical ingredients that are approved for use in sunscreen products. These sunscreens need to be applied 15-30 minutes before sun exposure to "activate." They are also generally reapplied every two hours while exposed to the sun. While physical blockers create a shield on the skin to block and absorb the sun's UVA and UVB rays, chemical sunscreens absorb the sun's rays and dissipate them. Instead, those formulations contain a mix of chemical ingredients or UV Filters. Today, several sunscreen formulas don't contain either Titanium Dioxide and Zinc Oxide. For those with deeper skin tones, even a micronized zinc oxide and titanium dioxide formula may not be enough to render the sunscreen transparent upon application. This dramatically reduces the grey or white cast left behind by these types of sunscreens. Many brands now use micronized Titanium Dioxide and Zinc Oxide in their formulas. Over the years, formulas containing physical blockers have gotten more elegant.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |