Skin and Sun Tanning (or Burning) and What About Sunscreen

Skin, the body’s largest organ, is its protective covering that receives external sensory stimuli. It consists of the outer layer, or epidermis, over a thicker layer, the dermis.

Epidermis is made of cells that include immune defenses, sensory receptors, pigments cells and keratin producing cells. Keratin producing cells migrate to the surface and form a dead, relatively dry outer layer that continuously sloughs off.

Dermis contains sensory nerves and blood vessels within connective tissue. Fibers of collagen and elastin make skin tough yet elastic.

Is a suntan, as opposed to sunburn, good for you?

No, because there is no safe way to tan. Melanin is the body’s substance that gives pigmentation to skin and helps protect the skin from sun. A tan is a telltale sign of skin damage. When ultraviolet rays penetrate the epidermis, the skin’s outer layer, the body produces more melanin in response to the injury.

With each tan, damage accumulates. It increases your risk for all types of skin cancer. The U.S. Department of Health and Human Services and International Agency for Research on Cancer panel have declared ultraviolet radiation from the sun and from artificial sources, such as tanning beds and sunlamps, to be a known carcinogen (cancer-causing substance).

Ultraviolet light damage also accelerates the aging process. Chronic exposure to ultraviolet light, both natural and artificial, changes the skin’s texture, causing wrinkles and age spots.

What in ultraviolet light causes the damage?

Ultraviolet A and ultraviolet B rays can each cause harm.

  • UVA rays penetrate deeper into the dermis, the thickest layer of the skin. UVA rays can cause suppression of the immune system, making it harder for your body to protect against development and spread of skin cancer. UVA rays also lead to premature aging of the skin through wrinkling and age spots.
  • UVB rays are the burning rays. They are the primary cause of sunburn.

How do you treat sunburn?

  • It can take up to 24 hours for all of the effects of sunburn to show.
  • The two most common types are first-degree and second-degree burns.
  • First-degree sunburns cause redness, but will heal, sometimes with peeling, within a few days. Cool baths, moisturizers and over-the-counter hydrocortisone creams can help.
  • Avoid “caine” products, such a benzocaine, as they might cause sensitivity to broad range of chemicals. Anti-inflammatories, such as aspirin or ibuprofen, can help ease the pain.
  • Second-degree sunburns cause blisters. Such burns can be considered an emergency, if a large area of skin is affected. Don’t break the blisters because it can delay healing and lead to infection. A layer of gauze may be used to cover the area until healed.
  • If severe sunburn is accompanied by headache, chills or fever, seek medical help immediately.

What about sun and vitamin D?

  • Sun exposure prompts vitamin D production in the skin.
  • Wearing sunscreen does decrease the production of vitamin D. Those who worry about not getting enough vitamin D should talk to their doctors about getting sufficient vitamin D from food and vitamin supplements.

Now what about Sunscreen


Is SPF 30 twice as protective as SPF 15?  Sadly no,

Definition and Workings of Sunscreen:

  • Sunscreen is a lotion formulated with unique chemical components to absorb UV light.
  • When sunscreen is applied to the skin, the chemical molecules form an invisible, protective layer on the skin that protects from penetrating UV rays.
  • All sunscreens protect from UVB rays, but only “Broad-Spectrum” sunscreens protect from both UVB and UVA rays.
  • UVB rays affect the top layers of the skin and are responsible for Burning.
  • UVA rays affect the lower layers of the skin and are responsible for Aging.
  • Remember to always buy a sunscreen that is broad-spectrum!

SPF… What’s it All About?

  • SPF stands for “Sun Protection Factor.”
  • Always wear a sunscreen with an SPF 15 or higher!
  • SPF was developed to describe the amount of protection that a sunscreen provides. No sunscreen can protect your skin from all of the UV rays, but a higher SPF number indicates protection from more rays.
  • The SPF number tells you how much longer you can stay outside without burning while wearing the sunscreen product as opposed to not wearing any sun protection product. SPF measures “time to burn.”

SPF Math

SPF Number x Time to Burn Without Sun Protection = Time to Burn while wearing sunscreen*

*assuming that sunscreen is applied properly

Example: If your skin would burn in 10 minutes in the afternoon sun without any sun protection, and you applied a sunscreen with an SPF 15, you would have 15 x 10 = 150 minutes (2.5 hours) before you would burn.

Percentage of Protection from damaging UV rays:
SPF 15 = 92%
SPF 30 = 97%
SPF 40 = 97.5%

There is some controversy about very high SPF numbers and just how much more protection they provide. As you can see from the percentages of protection of the different SPF numbers, the difference in UV ray protection in SPF numbers becomes minimal as the number increases past about 30 or 40. The difference of protection between SPF 15 and SPF 30 is great (5%), but the difference between SPF 30 and SPF 40 is minimal (0.5%).


The Confusing Part About Sunscreen

  • Many people think that SPF values can be added. Actually, SPF values cannot be added – if you apply a sunscreen of 8 and then one of 12, you will not have the protection of an SPF 20. You will only be getting the protection of an SPF 12.
  • Reapplication only helps to ensure that you have the amount of protection and time before you burn that you calculated when you first applied sunscreen that day. Since no sunscreens can protect your skin from all UV rays, some rays will get through.
  • After your calculated “time to burn” has expired, your skin has absorbed all the UV rays that it can handle before it will start to burn. Even if you reapply sunscreen at this point, you will still burn because some rays will get through to your skin and your skin has already been saturated with UV. Therefore, you need to get out of the sun at this point and let your skin rest before exposing it to more rays.
  • Reapplication only ensures that you have your original time outside – sunscreen can wear off because of sweat, wind, and other factors you need to reapply in order to be protected.
  • So what’s the lesson to be learned about sunscreen? If you know that you will be in the sun for a long period of time, start with a higher-SPF sunscreen in order to have protection for the entire time that you are exposed.

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