How does sunscreen work?

The white goopy stuff does more than prevent sunburns. It's a crucial defense against the sun's rays, protecting your skin at the cellular level.

The sun, like every star out there, is constantly spewing out a spectrum of light. Some of this light, particularly ultraviolet (UV) rays, has some serious power. When UV light hits your skin cells, it wreaks havoc, smashing through cell walls and even damaging DNA. Your body responds with inflammation. Blood vessels dilate, skin turns red and hot, and those damaged nerve endings start screaming. Get the aloe.

But UV rays don't just cause burns - they also prematurely age the skin. UV exposure breaks down collagen and elastin, the proteins that keep your skin firm and elastic. This leads to wrinkles, sagging, and that leathery texture that screams "I've surfed here since you were born." 

So how does sunscreen keep you from looking aged and burnt? There are two main types: chemical and mineral. Chemical sunscreens, the ones with that classic beach-day smell, rely on energy conversion. They penetrate the skin and absorb UV radiation, then dissipate it as heat. It's similar to how melanin, the pigment that gives skin its color, protects your skin naturally. Darker skin tones have more melanin, which is why it has some built-in sun protection.

Mineral sunscreens, on the other hand, rely on reflection instead of absorption. They sit on top of your skin, scattering and reflecting UV rays before they can even touch your cells. Think of it as a cream made of tiny mirrors.

Chemical sunscreen dissipates the UV energy as heat, while mineral sunscreen reflects it away.

But not all skin is created equal when it comes to sun protection. Your lips, ears, and the skin around your eyes are especially vulnerable to UV damage. These areas have thinner skin and fewer melanocytes (the cells that produce melanin), so are particularly important to protect. 

Some chemical sunscreen ingredients, particularly oxybenzone and octinoxate, have been linked to coral bleaching. Not exactly what you want to be leaving behind in the lineup. Mineral sunscreens aren't totally in the clear either - there's ongoing research into whether nanoparticle forms might be small enough to cause physical damage to marine organisms.

So what's an environmentally conscious surfer to do? If you're going the chemical route, look for formulas without oxybenzone and octinoxate. For mineral options, consider non-nano versions. But the best bet for both your skin and the ocean? Cover up when you can. Use a topper during the summer, throw on a hat between sets, and remember - the best protection is staying real deep in the pocket.

Further Reading:

Light Spectrum

Chemical vs. Mineral Sunscreen