Sun Protection Factor (SPF) indicates how long it will take for ultraviolet B (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.

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 does physically block UV rays by acting like tiny mirrors on the skin reflecting and refracting the 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.)

In Sunscreens: Development: Evaluation, and Regulatory Aspects, Nicholas J Lowe (Editor), renowned dermatologist and Clinical Professor of Dermatology at UCLA School of Medicine, takes a closer look at mineral UVA blockers, stating that 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 ultraviolet radiation (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 photosensitivity. Not all mineral powders have an SPF rating. If they do, the SPF rating must be specified on the label.

According to the American Academy of Dermatology you should use enough sunscreen to generously coat all skin that will not be covered by clothing. One ounce, enough to fill a shot glass, is considered the amount needed to cover the exposed areas of the entire body. You should apply our sunscreen liberally and evenly over face and body 15 minutes before sun exposure and re-apply approximately every two hours or after swimming or sweating heavily according to packaging directions._ jane iredale_ sunscreen products are water-resistant up to 40 Minutes. This means that the sunscreen remains effective for 40 minutes while you are swimming or sweating.

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 penetrates 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 4 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”.

It’s not safe to rely on sunscreens alone to prevent melanoma, which is now the 10th most common type of cancer in the U.S. Most dermatologists feel that it takes over 20 years for melanoma to develop. Those with this cancer today had to have been exposed to the sun's damage two decades ago before effective sunscreens had been developed. Dr. Ceilley, former president of the American Academy of Dermatology, states, “Sun protection should begin in childhood and continue throughout life. Overwhelming evidence supports the beneficial effect of sunscreen usage, not only in preventing painful sunburn, but also in preventing photoaging and skin cancer, including melanoma.”

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! More than 90% of the visible signs of aging are due to sun exposure. And that means all sun exposure, because ultraviolet radiation damage 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.

Some damage can be reversed or minimized but only if the skin is always protected from the sun. There are many excellent skin care products and nutritional supplements on the market today that can substantially aid the skin in repairing sun damage. But they do little good if they aren't combined with sun protection – so remember to wear your sunscreen, and a hat!

Lines, wrinkles and sagging are the direct result of sun damage to the underlying collagen and elastin fibers. Hyperpigmentation can be caused or exacerbated by sun irritation to the melanocytes (the pigment producing cells), which in turn causes overproduction of melanin, which is in fact the body’s attempt to protect itself. Add in hypopigmented macules, telangiectasias and raised, rough precancerous actinic keratoses (the most common skin precancers) and the result of tanning is not pretty.