As summer vastly approaches it is within our human nature to get outside and explore, be by the water, or do the oh so famous one, SUNTAN. Millennials are famous for believing that having a nice tan is attractive and makes you look healthier. Thus resulting in relaxing outside under the sun with a nice drink and a good book. Thus also resulting in the most common form of cancer in the USA, skin cancer. Don't worry, I'm not going to lecture you on the importance of sunscreen and staying in the shade. Instead this article is going to go more into biology, chemistry and physics behind the sunburn from the start of the sun all the way down to your skin cells, change of skin color and a little bit of what makes sunscreen effective(because what's a sunburn article without mentioning sunscreen). Now there is no such thing as a healthy or safe suntan but I will go into how to get a suntan while avoiding skin aging, skin wrinkling and reducing risk of skin cancer.
Let's start with the source of a sunburn, the sun. Many people ask, why does the sun emit that causes sunburns? Well, the sun emits many different photons, wavelengths, and electromagnetic energies. However, only three out of all the different energies hit the ground. Of that 53% is IR or infrared, 43 % is visible light(see article on visible light) and just only 4% is UV(ultraviolet) rays. Check out figure 1 below I drew up for a quick visual and explanation of what those three energies are.
As you may have observed in figure 1, the ultraviolet(UV) radiation from the sun is what penetrates the skin and causes sunburns. Invisible to the human eye, up to 80% of UV can penetrate through clouds and can reflect off snow and sand. So even when it's cloudy out or you're under the shade you still are exposed to the UV rays.
Now that we have learned the sun emits ultraviolet radiation, lets go into how it penetrates our skin. There are two types of UV rays that reach our skin, UVB and UVA.
UVB is what gives you vitamin D. It has a shorter wavelength so it only affects the outer layers of your skin causing sunburns, blisters, skin cancer, and suntans. However, 90% of UVB is absorbed by the ozone layer and does not penetrate through glass. So you're safe from UVB while driving.
UVA is the more dangerous one. It has a longer wavelength and penetrates right through the atmosphere making up 90% of the UV. UVA also penetrates deeper through your skin producing free radicals that damage the DNA of your skin cells causing your skin to age quicker and develop wrinkles, we definitely don't want old and wrinkly looking suntans. This also causes sunburns and develops skin cancer as well. Check out figure 2 below for a visual of how far UVA penetrates through your skin
Our bodies do have a defense mechanisms to protect ourselves from UV rays called melanin. Melanin are little molecules present in our skin cells that absorbs the UV rays and protects your DNA for as long as it can. Melanin also defines our skin color, the more melanin we have the darker our skin becomes. So the reason why we get tans is because after your skin cells get damaged your body will produce more melanin than before to protect your skin cells DNA thus making your skin color darker.
This Melanin does have it's limits and eventually breaks. There are a few ways the UV rays can break through. One way is that the UV rays causes your skin cells to produce free radicals which then excites your melanin to the point were it kills your skin cells DNA. While this is happening your skin cells start producing warning molecules and eventually your body will rush blood cells to the area where the skins cells are being damaged so they can be repaired, this is what causes the redness. It's at this point were it's really best to wait until your skin is fully repaired before UV exposure.
Remember having to peel off dead skin after a sunburn? In general, your stem cells produced layers of keratinocytes. But during UV damage to your skin cells the keratinocytes don't mature properly thus bunching up at the surface of the skin and starts to peel off.
Now let's go into the repair process. Your body have enzymes which repair a lot of the DNA damage caused by the UV. However, the enzymes don't always repair all of the DNA which becomes the real problem. The unfixed DNA cells will then start to replicate itself and can produce a mutating of the damaged. This can become cancerous sometime down the road. So it is absolutely important to take care of your skin and limit all UV exposure during the repair process for enzymes to repair as much skin cell DNA as possible. After your skin cells are repaired and the melanin has tanned you up it's time to put on that sunscreen and not risk skin cancer anymore!
Telling some people, especially millennials to put as much sunscreen on as possible is a loosing battle. Why? Because you don't get as much of a suntan. There is no sunscreen that protects you 100% so yeah you'll still get a slight tan but for some people that's not good enough. So I'll talk of a more safer way of tanning even though we discourage damaging your skin.
So we want to make sure your sunscreen has the the ingredient avobenzone in it to protect you from UVA. As stated ealier, UVA causes your skin to age and wrinkle and penetrates deep into the dermis layer of your skin. Aside from zinc oxide which is the best and will protect you from both UVA and UVB, avobenzone is second best for UVA. The SPF rating of a sunscreen only protects you from UVB but not so much UVA. So if you really really want to suntan make sure your sunscreen has high avobenzone and lower SPF of 15, 10 or even 5. That way you will have more protection of UVA and still some protection of UVB.
So that concludes this article for now. I wanted to go a little deeper into the biology of skin cells but I've realized this article is getting pretty long. Did you like what you read? Awesome don't hesitate to subscribe! Didn't like what you read? Awesome feel free to contact me!
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