Sun Protection Factor (SPF) indicates how long it will take for UVB rays to redden your skin when you use a sun protection product, compared to how long the skin would take to redden without the product. So, the SPF number gives you some idea of how long you can stay in the sun without burning. For example, if you normally burn in 10 minutes without sunscreen and you've applied a liberal dose of a sunscreen with an SPF number of 15, you should be protected from sunburn for 150 minutes. This does not mean that you are protected from other radiation damage. A broad spectrum sunscreen is required to give protection in the UVA range as well. An SPF rating does not measure Ultraviolet A (UVA) protection.
Yes, all jane iredale sunscreen products are water resistant to 40 Minutes. The new FDA final rule on the labeling and testing of sunscreen products, does not permit the labeling of sunscreen as “waterproof" or "sweatproof," and only allows “Water Resistance” claims if the sunscreen remains effective for 40 or 80 minutes while swimming or sweating. The new testing techniques have resulted in a 40-minute designation for all of our sunscreen products.
Under the new FDA final rule on the labeling and testing of sunscreen products the word "Sunblock" is no longer allowed. The FDA is trying to eliminate any confusion the public may have or sense of false security. However, the titanium dioxide and zinc oxide in our bases literally block UV rays by acting like tiny mirrors on the skin reflecting, refracting and absorbing rays. Most chemical sunscreens have highly efficient absorption capabilities through the UVB, partly the UVA, and in some instances infrared wavelengths. Once the chemicals have absorbed their limit, the sunscreen ceases to be effective. (Absorption is the process in which light is "lost" when it falls on a material. The light is not actually lost, but is converted into some other energy, such as heat.)
Dr. Nicholas J. Lowe and Dr. Josia Friedlander, both from the Skin Research Foundation of California, said in their recent book Sunscreens: Development, Evaluation, and Regulatory Aspects: A new subclass of physical blockers, micronized reflecting powders, have more recently been made available from a variety of manufacturers. Unlike traditional physical blockers, micronized reflecting powders are less visible, yet provide broad-spectrum protection against UVR. These should prove useful in UVR-sensitive patients resistant to older physical blockers for cosmetic reasons. An additional benefit is that they do not cause photosensitization. Not all mineral powders have an SPF rating. If they do, the SPF rating must be specified on the label.
Much more than you think! At a recent conference of dermatologists, we learned that if you imagine your cupped hand mounded with shaving cream, that's the amount you must apply to achieve the SPF rating that the product claims. The FDA suggests: to get the maximum protection from your sunscreen, apply at least one large handful about 30 minutes before you go outside, and reapply after swimming, toweling dry, or participating in any vigorous activity that causes heavy perspiration.
UVB rays were once thought to be the culprits because they penetrate and affect the epidermis, but UVA rays are now known to be equally if not more damaging. According to Dr. Madhu A. Pathak at the Harvard Medical School; 'Many lines of evidence indicate that the primary biological actions of UVA radiation involve DNA damage'. UVB emissions from the sun undergo significant seasonal variations; the UVA emissions, however, do not appreciably change over the course of the year. The amount of solar UVA reaching the earth's surface is much greater than that of UVB. Also, UVA is transmitted by most window glass and many plastics that do not transmit UVB. Always check to make sure your sunscreen protects from UVB and UVA, but be aware that regardless of the advertising no sunscreen product screens out all UV rays. The best defense is to try to minimize your exposure between the hours of 10 a.m. and 3 p.m. The effects of infrared rays (felt by the body as heat) are not fully known, but according to Drs. Lorraine and Albert Kligman from the University of Pennsylvania; 'They cannot be ignored in connection with photoaging'.
No! A tan is a sign of injury. It is the body's attempt to increase sun protection after the skin is already permanently damaged by an overdose of ultraviolet radiation! 80% of the visible signs of aging are due to sun exposure. And that means all sun exposure, because radiation is cumulative. Walking to the mailbox, getting in your car, and sitting by the window all count! Unprotected exposure to the sun is like sitting in a time machine on fast-forward.