Summer is for long days out in the sun tanning and playing. By the end of it, many look bronzed and have a healthy glow. We all know that that much time in the sun, especially the hot summer sun, can make it very important to put on sunscreen. But why exactly are we rubbing this lotion all over our skin?
First, it’s important to know about the different type of ultraviolet radiation – more commonly known as UV Radiation. UV radiation falls on what is called the electromagnetic spectrum – a spectrum of different “waves.”
Different waves, like radio wave, microwaves, and light waves travel with different wavelengths. A wavelength is the distance between one peak/crest of a wave to the next. Think of it like hills or mountains – the distance from one summit to the next. So, the longer the distance, the higher the wavelength, the slower the wave.
There are 3 types of UV radiation, UVA, UVB, UVC, and the only difference between the three at a fundamental level is the wavelength. (This is where “UVA/UVB protection” comes from!)
UVA falls between 320-400 nanometers, nm (nano = 10^-9 or 0.000000001, so really really small). This is actually the largest of the three wavelengths. These account for about 95% of the UV radiation that actually reaches the Earth’s surface, reaching us. It also penetrates deepest into the skin.
UVB falls between 290-320 nm, so the wavelengths are slightly shorter, or closer together. These waves account for about 5% of the solar UV radiation that reaches us, and though it does not penetrate as deep as UVA, it can still penetrate the skin to some extent.
UVC has a wavelength between 290-100 nm. These are the smallest UV wavelengths and do not reach the surface. They are filtered out by the ozone in the atmosphere.
Why does this all matter though? Why does it matter if waves are penetrating the skin? Well, these waves can actually mess with your DNA – which can cause skin cancer. When DNA is damaged, the cells affected cannot function right, and many times can go “rogue.” Cancer is essentially rogue cells that have multiplied. So, because UVA and UVB can damage skin cells, they can contribute to skin cancer.
This is why we use sunscreen! It has some important blockers in it! There are different types of active ingredients in sunscreen – at this point 17 have been approved for use in the US, and the EU has approved 28! These chemicals can absorb and scatter the various waves.
Normally, several different chemicals are in your basic sunscreen to ensure full protection. Some chemicals block UVA, some block UVB, and some block both!
It’s okay to spend plenty of time in the sun this summer – enjoy yourself! Just make sure that you are protected now that you know why we use sunscreen.
