The sun emits 3 types of UV (ultraviolet) rays: A, B & C. Let's focus on the rays we can do something about so forget about UVC (for now). UVC (short wave) rays are fatal, and were the ozone layer not blocking those rays, you wouldn't be reading this article. While we know that the ozone layer is depleting, it's best left to scientific minds to worry about UVC radiation.
UVB (medium wave) rays from the sun are also mostly filtered out by the ozone layer. We know about these rays because we literally feel them, as they cause the skin to burn. The bad news is that UVB rays not only cause sunburn, according to the EPA, UVB is particularly effective at damaging DNA. It causes skin melanoma and other types of skin cancer. Furthermore, exposure to UVB rays can compromise the immune system as demonstrated in a US study on how UVB rays can trigger herpes cold sores. Moreover, UVB rays cause the dreaded "sunspots" or freckles that often show up on our skin later in life. All those hours of fun in the sun often result in thousands of hard earned dollars spent during many painful minutes under an IPL laser with the hopes of erasing those unsightly spots.
Nevertheless, UVB is a source for Vitamin D, which our bodies need but does not produce. Vitamin D can be obtained from certain foods (the preferred source) or exposure to UVB light. However, according to the World Health Organization(WHO), 5 to 15 minutes of casual sun exposure two to three times a week is sufficient to keep your vitamin D levels high. If you're closer to the equator, even shorter periods of exposure suffice.
UVA (long wave) rays from the sun are not absorbed by the ozone layer and make up 98.7% of UV radiation that reaches the Earth's surface. The long UVA rays penetrate the skin at a deeper level than UVB and damage collagen & elastin, compromising the skins' structural support which results in droopy, crepey skin. UVA rays are the major cause of photoaging or premature aging -the operative word here being "premature." Per the EPA, up to 90 percent of visible skin changes commonly attributed to aging are caused by the sun. With proper sun protection, most premature aging of the skin can be avoided!
If you aren't concerned with the esthetic effects of UVA than hopefully the health effects will cause you to take notice. According to the Skin Cancer Foundation, UVA contributes to and may even initiate the development of skin cancers. What's worse, most of us are exposed to large amounts of UVA throughout our lifetime because they are 30 to 50 times more prevalent than UVB rays. UVA rays are the same strength year round and penetrate clouds & glass making UVA rays much more insidious than UVB rays. That means you still need to wear sunscreen while driving to and from work on a rainy day.
Notice I only mentioned UV rays from the sun thus far. Think you're safe indoors? As Marta mentioned in a previous post "Even those that shy away from the sun should be cautious." Research from the FDA's Center for Devices and Radiological Health showed that although indoor workers typically receive 3 to 9 times less UV exposure than those outdoors, only the indoor group had an increased incidence of malignant skin cancer." Don't work in the corner office with the fabulous view? Most UVA light is also emitted by fluorescent lamps due to the peak emission of mercury within the bulb. According to the FDA, other sources of UV rays include mercury vapor lighting often found in stadiums and school gyms. All fluorescent tubes used for domestic and commercial lighting are mercury UV emission bulbs at heart. Yes, I even wear sunscreen when I attend New York Ranger hockey games.
What's even more alarming is that the incidents of skin cancer have increased approximately 300% over the last 15+ years according to the Archives of Dermatology. The latest Skin Cancer Foundation figures confirm that skin cancer, the world's most common cancer, is truly an epidemic. 1 in 5 Americans will develop skin cancer over the course of a lifetime. How is this possible when we currently have unprecedented access to sunscreen? In my view, there are 2 primary reasons: UVA is the most commonly encountered type of UV light, and the ozone layer is slowly depleting, thereby enabling more UVB rays to reach the earth's surface.
Do you need to run from the sun? No, but being aware of how much sun exposure you actually receive and counteracting it by protecting yourself with a daily "broad spectrum" sunscreen is key. It's important to keep in mind that Sun Protection Factor (SPF) only addresses UVB rays, meaning the average amount of time you can be exposed to UVB rays before burning. Think of it this way: A is for 'aging' rays & B is for 'burning' rays - but both cause skin cancer! Only within the last few years have US manufacturers started formulating "broad spectrum" sunscreens to address both UVA & UVB rays. Unfortunately, the active UVA blocking ingredients used in the US are often avobenzone & oxybenzone. Check this out on Neutrogena before you slather on sunscreens with those ingredients. The best sun protection options in the US are sunscreens with zinc oxide and/or titanium dioxide which are both very effective physical blockers.
I hope that the above will encourage you to wear sunscreen daily, both from a health & esthetic viewpoint. And for those inclined to go the extra mile, read on about how antioxidants make sunscreen even better!