It's about halfway through the summer which mean that the average American has approximately three mosquito bites. (Not true.) After all, nothing says summer like bites, an obsessive reliance on air conditioning, and melanin production in overdrive. From sunburn to sunkissed, why does skin brown (or burn) like a thanksgiving bird?
The main players here are melanin and the Sun. Melanin is the pigment that gives hair, eye, and skin color. While most humans have similar concentrations of melanin in their skin, on an ethnic group and individual level, people produce different amounts of melanin.
When the Sun throws down it’s rays to give that special cowabunga feel to beach day, two different UV radiations interact with your skin – UVA and UVB. While both UVA and UVB are found near the surface of the Earth, UVB is partially absorbed by the ozone layer. (Thanks, dude!) Once the radiation touches your skin, your cells respond with either “Yo, we need to ramp up melanin production stat!” if you have fairer skin or “Man, glad we have this melanin to protect us!” if you have darker skin. No matter your skin tone, too much exposure means a swift exit to sunburn city.
UVA and UVB interact differently with your skin, however. Think of UVA and UVB like a fly and a bee, respectively. UVA is there most of the time, isn’t blocked as easily from sunscreen, and gives you a nice glow that is also damaging to your DNA and carcinogenic. After damaging your DNA, which happens even to people with darker skin, UVA makes your body produce melanin, but the tan will fade after a short bit. Just like the fly, it's there and an annoying part of life where we gotsta deal.
UVB, on the other hand, can be useful like our bee friends. It helps produce Vitamin D in skin, is blocked by most sunscreens, and creates a deeper tan that protects you better in the future from the sun’s rays. But when UVB strikes, it strikes hard. While you can get a sunburn from both sets of UV rays, you’re more likely to get a sunburn from overexposure to UVB rays and it may cause skin cancer as well.
So while you get your summer on before pumpkin-spiced-cable-knit boots make their return, remember to wear sunscreen, sunglasses, and chapstick when going out in the sun. Better over protected than burnt now and leathery later!