Ultraviolet radiation from the sun, also called UV radiation, is quite harmful to our skin. Unfortunately, this is more than people might think. I have written this article so that my readers can better understand the effects of sun exposure. As you will see, although tanned skin can be considered socially desirable by many, its definitely a price to pay!
Its helpful to first know the skins basic anatomy, even though Ill keep it as easy as possible!
There are three layers on the skin:
Epidermis: This is the outer surface layer and it is generally about the thickness of a sheet of paper. It contains cells called melanocytes that produce a brown pigment called melanin. Melanin is what gives our skin the familiar tan look. Each individual has a natural amount of melanin that helps to give his skin it is a natural distinctive staining. When exposed to the sun, the melanocytes respond to the suns ultraviolet radiation and produce more melanin as a way to protect the skin against radiation damage.
Dermis: This is the next layer under the epidermis. Although quite complicated, some of the main topics in dermis blood vessels, hair follicles, nerve endings, collagen and elastin are. This is the layer that mainly gives the skin its substance and youthful appearance.
Subcutaneous: This layer is technically not really skin, but rather it goes to the skin against deeper tissues with fibrous bands. It is also called hypodermis. This layer usually contains fat cells, nerve endings, blood vessels and hair follicles. We are not really worried about this layer when we consider UV damage to the skin.
The sun is emitting constant electromagnetic radiation, most of which are blocked by different gases in our atmosphere, such as ozone. UV radiation is part of this electromagnetic radiation that passes through the atmosphere and reaches us.
We usually see the terms UVA and UVB used when referring to sunscreen. These terms refer to specific types of UV radiation that reach us and affect our skin. The following are the important differences between the two.
UVA: Most of the radiation that reaches us is UVA. It is a longer wavelength than UVB and therefore can penetrate the atmosphere, cloud cover and window glass much lighter than UVB. UVA radiation can easily penetrate the skin and reach the deeper layer, dermis, where it damages collagen and elastin, and indirectly leads to DNA damage through the production of free radicals. UVA does not cause tanning so it causes damage in secret without any immediate evidence such as tan. In fact, the SPF value of sunscreen solely refers to the blocking of UVB radiation.
UVB: It is UVB radiation that causes tanning. UVB penetrates the skin, causing collagen and elastin damage, and also directly causes DNA damage. It is this direct DNA damage that leads to what we know as tan. UVB radiation does not penetrate glass. This can give a false sense of security because you will not burn sunlight passing through glass, and you may think you are not affected by the sun. This is a terrible misconception because UVA radiation passes through glass and it will damage your skin.
As I mentioned earlier, UVA and UVB cause both damage to our DNA, but they do it differently. UVA radiation indirectly causes DNA damage by producing free radicals which in turn damages DNA. UVB radiation directly causes DNA damage when it contacts DNA. Much of UVB as when our skin is converted to heat, but some of it damages our DNA and causes tanning. The damage to the DNA causes cell death, and then conceals the dead skin as it is usually seen after tanning.
I mentioned earlier that our skin produces melanin as a way to protect our skin against sun damage. Our skin responds to the attack of UVB radiation and increases melanin production in an effort to protect itself from potential damage. This is because melanin absorbs UV radiation and loses it as heat, which essentially neutralizes UV radiation. Melanin is what gives our skin a sunburnt look. This extra melanin production is why exposure to the sun will give us a tan.
A tan is actually a protective mechanism, and is proof that damage has already been done. It takes a few days for a sunrise to develop because the body needs time to produce additional melanin. Although mainly UVB rays cause sunburn, UVA rays can produce something of a fast but much shorter lasting tan by oxidizing the existing melanin, which makes it more noticeable.
Sunscreens provide protection against UVA and UVB radiation from the sun, but it has limitations, and there will still be some damage to the skin. Sunscreens only work as intended when they cover the skin, and they lose their effectiveness when they absorb the skin. When sunscreen absorbs the skin, they still help prevent sunburn, but they can lead to deeper damage to the skin.