UVA, UVB, SPF, and Sunless Tanning

Ultraviolet radiation has two main components which are important to developing a tan and developing skin cancer, premature aging of the skin, and the breakdown of the supporting elements of the skin. These two components are UVA and UVB.

In very simple terms UVB is responsible for the development of tanned skin and sunburns. UVB stimulates cells within the skin called melanocytes that then produce a substance called melanin. Melanin has a dark pigmentation giving the skin the appearance of a tan. Melanin can also cause unevenness in skin color, which may be especially noticeable in the face. This unevenness of facial skin color is often referred to as melasma. Too much UVB and skin damage occurs leading to a sunburn. UVB exposure may also lead to the development of squamous cell skin cancer and is a major source of skin cell DNA damage.

Sunburns can be avoided and melasma can be improved by using a sunscreen with a high SPF (sun protection factor) rating. Generally a sunscreen with a SPF rating of 20 or higher is adequate to protect the skin from burning. (It must be reapplied regularly when sweating and/or swimming) Be aware, however, that the SPF rating applies only to the ability of the sunscreen to block UVB. It has no relationship to the ability of the sunscreen to block UVA.

In simple terms, UVA is the largest portion of UV radiation that reaches the earth and may play a role in immunosupression and the development of melanomas Melanomas are deadly skin cancers which even when relatively small can spread (commonly to the lymph nodes and then to the brain) and lead to incurable disease and death. UVA can pass through glass and penetrates deep into the skin leading to skin wrinkling and aging. SPF ratings of sunscreens give no indication of how well they protect from UVA radiation. It is always important to read the fine print of the sunscreen to see if UVA protection is also given. Ingredients such as zinc oxide and avobenzone offer excellent UVA protection.

UV radiation also causes a breakdown in the collagen and elastin of the skin. This leads to premature aging of the skin, an acceleration of wrinkle development and loss of skin elasticity and resiliency. Unfortunately, the damage caused by UV radiation is not simply reversed by stopping or decreasing UV exposure. Much of the damage can be permanent and may not show up for several years. Those of us who grew up in the 60’s are now seeing and realizing the damage that all that sun exposure has done to the skin.

Sunscreens are considered “water resistant” if they retain their SPF protection after two 20 minute periods of water immersion. If a sunscreen retains its SPF protection after four 20 minute periods of water immersion they may be classified as “very water resistant”.

Sunless tans are the solution for the desire for color without the risk of skin damage. The spray on or rub-on tanning formulations offer the ability to have a brown color without damaging the skin. Today’s formulations are much improved over those a decade ago and the appearance of orange stripes is a thing of the past. You must, however, be aware that a sunless tan also offers NO protection from UV radiation. Wear a sunscreen over the sunless tan to protect the skin.

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