Tanning Series: Indoor UV Tanning


I am not condoning UV exposure or unnecessary use of tanning beds. Tan at your own risk if you are choosing to do so. Overexposure of UV light can cause skin damage, premature aging and increase the risk of skin cancer. Those who are required to use UV light as part of medical treatment should have a doctor's permission to do so and have regular body checks for any signs of skin cancer. If you are using UV light recreationally, please make sure you do not burn, use proper tanning products before entering the bed and wear eye protection. 

   Now that I have that out of the way, lets get into the ins and outs of tanning! I have much experience with every sort of type of tanning there is out there. I used to work in a tanning salon full-time for awhile and recently started back working at a salon about one day a week. I am going to cover UV tanning in this post, all other types/categories of tanning will be in the next set of posts in this series.

How UV Tanning Works 


   The epidermis of the human skin contains 5 layers: Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidia, and Stratum Corneum. These layers consist of mainly four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans cells. Keratinocytes are the most abundant of these cells in the epidermis. 

   Keratinocytes are the cells in the skin that produce keratin. Keratin is a tough, fibrous protein that gives the skin its protection. These cells are held together by desmosomes, the keratinocytes are pushed from the lowest layer of the epidermis, where the almost continuous mitosis occurs, to the highest layer. The further these cells are pushed and age, they begin to fill the cytoplasm of the cell with keratin. Once keratinocytes reach the surface, they are dead. The cells are flat sacs filled with keratin. Millions of these cells rub off our skin on a daily basis, and about every 30-45 days we have an entirely new epidermis. In a healthy epidermis, the cells generated match those that are lost at the skin's surface. Wherever the skin experiences friction, cell production and keratin formation are accelerated (ex. exfoliation) 

1. Stratum Basale (Basal Layer) 

   This is the deepest layer of the epidermis, it is firmly attached to the dermis in a wavy-like pattern. The Basal layer is known as the germinating layer, it consists of a single row of cells that are the youngest keratinocytes. Mitosis occurs almost continuously in this layer. About 10%-25% of the cells in this layer are melanocytes aka "melanin cells" that give our skin color. Melanocytes are spider-shaped and branch out to the keratinocytes in the Basal layer. Melanin is created in membrane lined granules which are then transferred through the cell to nearby keratinocytes. Basal layer keratinocytes end up containing more melanin than melanocytes. Melanin granules gather on the surface of the keratinocyte and form a protective layer over the cell's nucleus. 

2. Stratum Spinosum (Spiny Layer)

   This layer is the thickest of all five in the epidermis. Mitosis occurs in this layer, but not as frequently as the Basal layer. The keratinocytes in this layer have many spine-like extensions.

3. Stratum Granulosum (Granular Layer) 

   This layer consists of three to five layers of flattened keratinocytes. These cells provide the formation of keratin in the upper layers of the epidermis. The keratin in this layer secretes a waterproofing substance into the spaces between the cells which slows down water loss from the epidermis. That being said, the external walls of the cells thicken and become more resistant to destruction. Simply, the further the keratinocytes move up the layers, the stronger they become. 

4. Stratum Lucida (Clear Layer) 

   This is a layer only found in thicker skin (heels of feet, palms of hands, knees, etc...) This is a row of flat, dead keratinocytes. If put under an electron microscope, the cells look identical to the stratum corneum. 

5. Stratum Corneum (Horny Layer) 

   This is the outer most part of the epidermis, the top layer. It is very thick and the cells are completely filled with keratin. All organelles in the cells were digested away by the lysosome enzymes upon death, leaving only keratin behind. The keratin combined with the thickened plasma membranes of the cells defend the skin against minor abrasions and penetration. That is a prime example of one of our body's defense mechanisms! The average person will shed off 40lbs of dead skin in a life time.

   Skin color has 3 main contributors: melanin, carotene and hemoglobin. Carotene is a yellow to orange pigment derived from certain plant products, such as carrots or sweet potatoes. It will gather in the stratum corneum and in the fat tissue of the hypodermis. In Caucasian skin, hemoglobin from oxygenated blood gives a pink tone to those who do not have as much melanin as others. Melanin is the most abundant pigment in the skin, it is made from the amino acid Tyrosine and generated by melanocytes. All individuals have about the same amount of melanocytes, but heredity determines how much melanin is produced. There are 2 colors of melanin found in the skin: eumelanin and pheomelanin. Eumelanin can be black or brown, and pheomelanin can be a red tone. Depending on your ethnicity and genetics, you will have a certain combination of these melanins.  

   A person's skin type is determined by their genetics, skin type does not change due to tanning. This is your constitutive pigmentation you were born with. 

Electromagnetic Spectrum

   There are 4 general types of UV radiation on the Electromagnetic Spectrum (shown above): UVA, UVB, UVC and VUV. 

UVA (315-400 nm): The longest wavelength of the UV rays, closest to visible light. This wavelength is responsible for completing the tanning process and causes IPD (Immediate Pigment Darkening) within the epidermis. 

UVB (315-280 nm): Medium wavelength responsible for initiating the tanning process and is the primary wavelength for delayed tanning. This wavelength causes sunburn (erythema). 

UVC (280-200 nm): Short wavelength that is most harmful. This wavelength is virtually stopped by the ozone layer. It is use in sterilization and germicidal irradiation. NOT USED IN TANNING.

VUV (100-200 nm): Ozone production (can also occur within 240nm wavelength range from UVC) NOT USED IN TANNING.


Tanning Process

   When the skin is exposed to UV radiation, the epidermis of the skin synthesizes Vitamin D and performs melanogenesis. This is the process of tanning in the human body, which is a natural defense mechanism against the sun's rays. Constitutive pigmentation is the person's skin color determined by their genetics, which is a large factor in how dark and fast a person can tan, as well as their skin type. Facultative pigmentation is the level of a tan developed by a person who has been exposed to UV radiation, which is determined by constitutive pigmentation. 

   The body begins the process of melanogenesis when it is exposed to UVA and UVB radiation. In the base layer of the epidermis (Basal layer) is where the melanocytes generate melanin to be transferred to the keratinocytes, which will slowly move up each layer of the skin until it is shed off. The tanning process occurs in two phases: Immediate Pigment Darkening (IPD) and Delayed Tanning.

   Immediate pigment darkening occurs the moment the skin is exposed to UV radiation, specifically UVA. This is when the existing pigment in the skin is oxidized (aka darkened) giving an immediate color result. This can last a few minutes or a few days depending on previous exposure and skin type. Delayed tanning occurs 48-72 hours after exposure and increases over the course of 7-10 days. This is primarily caused by UVB rays, much less UVB is needed than UVA to start this process. The duration of delayed tanning depends mainly on repeat exposure to UV radiation. The duration of this process can last for several weeks or month depending on how frequent a person is tanning. This is due to the increase in the size of the melanocyte cells and abundance of melanosomes inside these cells. 


UV Tanning/Tanning Beds

   Tanning beds are a convenient way to get a sun-kissed glow even when there is no sun or bad weather! Some use tanning beds for medical purposes at the direction of a doctor. For example, I have severe psoriasis and with the help of medications and regular tanning, my body is completely clear of any lesions! Tanning was a safer option for me rather than continuing biologic injections and small doses of chemotherapy, the side effects were outweighing the benefits. UV exposure is used for many other medical conditions like eczema, vitamin D deficiency, seasonal affective disorder etc...

Indoor VS. Outdoor Tanning

   There are advantages with indoor tanning over outdoor tanning! A person has access to the following controls that goes into the process: Timer, eye protection, temperature control, electrical safety, lamp protection, equipment access/support etc...

Here are variables associated with outdoor UV exposure:

1. Solar Elevation (height of sun in the sky)

-This can determine the intensity of the outdoor UV depending on where it is located in the sky.

-Can vary by location, time of day, latitude and season.

-UV intensities are highest during summer in a 4hr period around noon, or 1pm if daylight savings is going on.

-UVB varies more with the time of day than UVA.

-When your shadow is shorter than your own height, you may receive half or more UVB during the 4hrs around solar noon on a clear, summer day. 

-During summertime, UVB is 2-3 times more intense in equatorial areas than Northern Europe. 

-At about 60° latitude the total UVB exposure during January-February can be less than one clear day's exposure during midsummer. 

2. Latitude and Altitude 

-UV intensity at earth's surface is related to the angle where the UV rays enter the atmosphere.

-In the tropics (near equator) the solar UV is more intense since it has less distance to enter the atmosphere.

-UV intensities increase with altitude since the amount of atmosphere able to absorb UV is lessened, this gives shorter UV wavelengths ability to reach higher altitude areas. 

-Skiers in high altitudes can be exposed to higher intensities of UV with snow as a excellent reflector.

3. Atmospheric Scattering

-Solar UV is made up of direct and scattered radiation.

-The sky appears blue since the blue rays from the sunlight are scattered by the atmosphere.

-UV is scattered even more than blue light and can lead to an increase in exposure. 

4. Clouds/Haze

-UV intensity is highest under cloudless skies.

-Clouds reduce UV intensity, thin clouds have little effect and under certain conditions can enhance UV intensity.

-Haze has higher amounts of water vapor, UV scatter increases and will result in a higher UV exposure.

-Haze and cloud cover can make a person feel cooler but the UV exposure can be high. 

5. Ground Reflection

-Reflective properties on the ground influence UV exposure.

-Most natural surfaces (grass, soil, water, etc.) reflect less than 10% of UV.

-Sand reflects 10-25% of UV.

-Fresh snow reflects 80% of UV.

-During spring in higher altitudes and under clear skies, reflection from snow can increase UV exposure to levels encountered during summertime. 

-Reflected UV is a key source of exposure to the eye, like acute effects such as snow blindness while skiing and photokeratitis at the beach, can result from reflected UV. 

Tanning Beds

   When using a tanning bed, it is always important to use the proper lotions and gradually increase your time in the beds to avoid sunburn.  Typically the tanning consultants at your salon are knowledgeable on the level of bed and time of exposure right for your skin type at that given moment. You will most likely fill out a consent form and a skin type questionnaire to give them an idea of where you are at then help you achieve your goal. Just remember: DO NOT BURN!!! 

   Let's go over the types of "levels" that you will find in salon beds. Levels are a simpler way to differentiate between bulbs.  

Base level: These usually contain more UVB than any other level, this is a base building level you should start out at to build color. The UVB rays are known as "burn rays" or "reddening rays" which means the pigment in your skin is increasing. Higher quantities of pigment generated from this bed will oxidize on higher levels leaving a deeper, long lasting color. 

Mid-level: These bulbs will generally contain less UVB rays and more UVA rays. This is a good transition bed when looking to further deepen your color you developed on a lower level bed containing more UVB. 

High-level: This level of bed will contain little to no UVB and contain mostly UVA rays. UVA rays oxidize the pigment that is already present in your skin making it a darker color. It is important to rotate levels between the base and high to prevent a decrease in the quantity of pigment in your skin. 

   For first time tanners or those coming back to tanning, you always should build a base on the lowest level of beds to create pigment in your body. The color will last longer when it is done this way. Many people will immediately choose a higher level bed and get good color, but it fades quickly. You can avoid this happening by building a base first, then alternating beds to deepen and prolong your color. 


Overview of MED and MMD/Exposure Schedule

   MMD (minimal melanogenic dose) is the lowest dose of UV to develop a visible tan and MED (minimal eyrthemal dose) is the threshold dose of UV to produce a sunburn. Both of these factors depend on a person's skin type and vary for each skin type. These values are standardized to help categorize sunlamps to give a more accurate depiction of how they should be used for certain skin types. Most tanning units will have a small information panel with a chart. These charts usually show skin type, recommended exposure types along with time frames of continuous exposure. Sessions cannot exceed more than once in a 24hr period. This is determined by the FDA and a strictly enforced law in tanning salons in the USA. 

      When a person starts UV exposure, it is a fraction of the maximum exposure time. As time goes on with regular exposure, the time can increase since a tan is being built, reducing the risk of burning and increasing a visible tan. Everyone has a different skin type and reaction to UV exposure. By following the printed chart on the tanning equipment, you can best determine how long your sessions should be. If your skin is pink 24hrs after your session, you are burnt. Keep in mind you should NEVER tan when you are burnt, no matter how minor it may be. 


Indoor Tanning Products

   It is imperative that you use tanning products that are meant for INDOOR tanning!!! If you do not, some products will deteriorate the acrylic in the tanning bed which makes it crack and all of the products that aren't formulated for indoor tanning will actually reduce your color. There are people think it is a way for the tanning consultant to make money, but it is actually to replace lost nutrients in your skin as well as to help you achieve the color you want quickly. Lotion will also help extend your tan!

   The products you have available for purchase in a tanning salon can consist of indoor tanning lotion (accelerators/intensifiers, natural bronzers, bronzers etc...) facial tanning lotions, tan extenders, specially formulated body lotions, self tanners, spray tan maintenance products, teeth whitening kits, tattoo protection, and skincare. Some salons offer many more products for an array of different skincare and cosmetic needs.


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