Tanning is the human body’s natural and intended response to ultraviolet light exposure. Throughout human evolution a tan has served as the body’s natural acquired protection against sunburn and overexposure. Today we know that a suntan achieved in a non-burning fashion, combined with proper use of sunscreen outdoors when sunburn is a possibility, is the best way to maximize the potential benefits of regular sun exposure while minimizing the risks that are associated with overexposure.
This section will explain how your skin develops a tan by first introducing ultraviolet light, introducing parts of the skin and then showing how UV light works with the skin to develop a tan.
Ultraviolet Light: There are several forms of ultraviolet rays emitted from the sun, two of which, UVA and UVB actually penetrate the Earth’s atmosphere. These are the same two UV rays used in tanning equipment. More UVA hits Earth than UVB because the atmosphere prevents the passage of shorter UV rays like UVB while allowing the majority of UVA to pass freely. The human eye cannot see ultraviolet light, however we can see the effects of ultraviolet light such as tan skin on the human body.
UVA and UVB light waves cause skin to tan and promote vitamin D production, an integral part of cellular function and overall metabolic health in the body. These same light rays can be replicated in special lamps used in tanning equipment. The ultraviolet portion of outdoor sunlight is approximately 95 percent UVA and 5 percent UVB, although atmospheric, seasonal and geographic variables change that ratio each time you step outside. So although UVA is the predominant ultraviolet light ray in sunshine that hits Earth, there is still an important percentage of UVB in sunshine.
Today’s indoor tanning units utilize a carefully controlled mix of both rays to help prevent indoor tanners from burning as easily or as quickly as they could by tanning outside, and also to create cosmetic tans in a controlled environment that minimize the risk of sunburn.
Why is the ratio of UVA to UVB important? While UVB is the portion of sunlight responsible for natural Vitamin D production in the body, it is also more intense than UVA light. Being more intense, UVB is significantly more effective at causing sunburn than UVA. Very few people realize that UVA emissions outdoors are virtually unchanged throughout the year. That is because the ozone layer does not block UVA rays at all. However, UVB levels change seasonally and throughout the day making one more prone to sunburn at peak times such as noon versus dusk. In a tanning salon, these levels are fixed in a controlled manner.
Understand Your Skin, Skin is the largest organ in the human body and protects it from harmful pollutants found in air, water and other things people come in contact with every day. Skin performs many other functions such as regulating body temperature, houses sensory receptors that help you feel things and synthesizes various body chemicals necessary for life. That’s why the condition of the skin is so important to good health.
Skin has many sections, but it generally is divided into three layers:
The top layer, or epidermis, is the one that produces a tan.
The middle layer, or dermis, contains collagen and other elastic materials important to the skin’s strength, and to its ability to fight off infection and repair itself. Blood vessels, nerve fibers and other structures are embedded in this layer.
The bottom layer, or subcutaneous tissue, primarily is composed of fat that binds the skin to the body. Subcutaneous tissue serves as the body’s food reserve, insulation and shock absorber.
Skin cells in the epidermis are constantly reproducing and pushing older cells upward to the surface of your skin where they are sloughed off daily. This top layer, the epidermitis contains special skin cells called melanocytes, which lie on the bottom of the epidermis. Melanocytes are pigment cells that help the skin tan once exposed to UV light.
Melanocytes produce melanin – a protein pigment which performs the very specific body function of protecting skin from overexposure to ultraviolet light. Thus, the presence of melanin in the skin colors it and protects it. Your body’s melanocytes naturally will produce a certain amount of melanin based on your heredity, which is why people have different skin types.
UVA, UVB and Their Role in Tanning
Melanocytes are prompted to produce additional melanin whenever ultraviolet light waves touch them, thereby making the skin darker to protect the body from overexposure. This produces a tan—literally, a browning of the skin. The color of the tan ultimately depends on heredity and previous exposure to ultraviolet light, two factors which predetermine the amount of melanin your skin will contain. This explains why some fair-skinned people can get dark tans and others cannot.
Of course, ultraviolet light can affect the skin in other ways. In excessive doses, it can cause sunburn – a reddening caused by the swelling or bursting of tiny blood vessels in the skin. Repeated burning is believed to be the greatest risk factor for long-term skin damage, which is why it is so important to prevent sunburn.
UVA and UVB waves have specific roles in the tanning process which are determined by their effects on skin. Although all ultraviolet light is capable of tanning skin, UVA and UVB are each efficient at different functions in the tanning process. For instance, melanin produced when your skin is exposed to UV light is naturally pinkish in tone. But ultraviolet light also oxidizes the melanin, turning it brown. UVB is more efficient at signaling melanocytes in your skin to begin producing more melanin, whereas UVA is more efficient at oxidizing the melanin your skin has already produced, turning it brown.
Therefore, your tanning packages should address a balance of exposure to UVA and UVB based on skin type. Understanding the balance between the amount of UVB exposure to promote melanin and UVA to turn it brown is important for picking which tanning package is right for you. There are also a range of lotions, moisturizers, and bronzers to aid in protecting the skin and replenishing nutrients while optimizing your tan.