- UVA-UVB Sun Rays
UVA-UVB Sun Rays
Author: Mary Gillespie
"U" ltra "V" iolet Light Rays
Skincare is concerned with three categories of light rays, ultra-violet, visible and infra-red rays. Ultra-violet or UV is divided into three sections according to their wavelengths from the sun to the earth. We are addressing the effects of UV rays on your skin, aging of your skin, why you should regulate your exposure, and sun protection use.
The longest ray was touted in the 1980's as the "safe" ray and sun beds were the rage. Some dermatologist backed this idea as a safe and healthy way to look your best. Since then, science has found this ray actually does more damage to the body than the shorter UVB ray. UVA is the same strength year round, it does not matter how close or how far away the sun is from the earth, and considered a light X ray penetrating light clothing, wind shields, office windows, and hats, to name a few. You can test this by putting a color bound book or fabric covered furniture in a sunny window for a few months. You will start to see the color fade as the rays work on the book or furniture. Often, busy women tell me they never go out in the sun, but their chest is permanently red and wrinkled, and their hands look old which I usually categorize as "free-way" or "commuter" aging. A pulled down head visor in a vehicle does not protect your hands on the steering wheel or exposed chest driving into the sun. Car pooling, commuting, or traveling congested areas, even several times a week, is enough to cause aging. When taking the train or plane is the sunlight on your hands or chest? Male skin is thicker, "free-way" or "commuter" aging affects them mostly by more brown spots on the exposed side of their face. Living in a sun state or country like, Mexico, and equator countries provide a constant sunny environment making a daily full spectrum sunscreen a necessity.
“Recent studies show that it takes relatively small amounts of repeated UVA exposure to cause photoaging in human skin. Only nine moderate dosages of UVA are necessary before changes are evident. (Lavker et al., J Am Acad Dermatol, 1995: Lowe et al., J Invert Dermatol, 1995)”. Reference, The Science Supporting Skinceuticals Sunblock Products, page 3.
A cause of cancer is UVA damage to cellular DNA. Dr. Marc Siegel, America Live, Fox News, 6/8/2012.
Body's Reaction to UVA
UVA shoots through the epidermis, disperses in the second major layer of your skin, the dermis, and accelerates the aging process. The dermis is called the "true skin" and slows its replacement or renewing rate around the age of 28 years. Skin after this age is considered "mature skin" and damage is not mended as well, if at all, fair skin people look in the mirror asking "What happened?”. The dermis is composed of collagen, elastin, blood vessels, nerve endings and ground substances, glycosaminoglycans (glahy-kohs-uh-mee-noh-glahy-kan) and mucopolysaccharides (myoo-koh-pol-ee-sak-uh-rahyd), providing a firm youthful mattress for your skin. Prolonged exposure to UVA cracks and shrinks collagen and elastin causing reduction, and allows the epidermis (top layer) to start drooping or hanging off the body, like baggy clothing. Blood vessels become permanently dilated giving a constant red flush to the skin. The few remaining melanocyte cells that are scattered in the dermis can either die making a permanent white spot or become over active leaving a brown spot. There are no lasers or procedure available at the moment guaranteeing the removal of these brown spots and some procedures make them worse. The water binding ground substances are less and ineffective making the skin dry. In the end, over exposure to this ray can put you in the dermatologist or plastic surgeon's office faster than any other aggravator. Not to mention the reported deaths of radiation poisoning from tanning beds. Be very careful and wear your sunscreen when exposed.
Skin, the protective covering of the body, is like paint on a new car and needs to be protected. Over time, leaving a new car in an over crowded parking lot with reckless drivers will certainly cause paint damage. Overtime, not protecting your skin from UVA rays will certainly cause sun or photodamage.
Long considered the "tanning ray" is strongest in northern hemisphere summer months or when parts of the earth orbit closest to the sun. When the earth orbits away from the sun in the northern hemisphere winter months it is harder to get a "suntan" because the rays can not easily reach the earth's surface. Sunblocks and sunscreens for many years only blocked the UVB ray as science was not clear on the body's reaction to UVA.
Body's Reaction to UVB
This ray only has the strength to penetrate the very top layer of your body called the epidermis which has the same thickness as a silk scarf. No blood vessels or nerve endings are present and is composed of keratinocytes (skin cells), basal cells and melanocyte cells. Melanocyte cells synthesize tyrosinase and the pigment melanin that is transferred to the keratinocytes or skin cells for color. UVB rays simulate the melanocyte cells to produce more melanin which is more color known as a suntan or if a very small area known as a freckle, brown or age spot, chloasma (usually hormones and sun), melasma, or hyperpigmentation in medical terms. Over exposure will cause tough, leathery skin and a coarse texture. Lines or winkles in a criss-cross pattern are a dead give away to sun damage.
The shortest from the sun, usually does not reach the earth's surface being absorbed by the ozone layer above the earth. Occasionally, articles are written on the ozone depletion and the possible exposure to UVC where only brief exposure can cause light sunburn. Prolonged exposure to UVC is considered fatal.
Sunlight regulates our biological clock and provides essential vitamin D. Common sense should be used in regulating your amount of time in the sun.