Last week I went on my first real vacation since I joined the working world. It’s been a long time since I was last at the beach, and it particularly struck me when I stepped onto the sand and thought, “Whoa, this stuff is hard to walk on.” I don’t remember that being a thing as a kid.

I also completely noobed it up by getting a sunburn on the first day, which got me thinking: “Is that an angry mole? Where’s the sunscreen? Am I gonna see God, Mommy? Am I gonna die?*”

Then I thought, “How does Sunscreen work?**”

Sunburns are caused by Ultraviolet radiation from the Sun. Sitting just beyond our visual range on the electromagnetic spectrum, UV light, while mostly non-ionizing, is just energetic enough to deal some damage. Also, while most of the UV light emitted is blocked by the Earth’s sweet, sweet Ozone layer, enough gets through to ruin your vacation.

The Goal: Block UV light. The Challenge: Do it without looking like you’re hiding from the Predator.

“Just catching some rays, dude.”

Early zinc oxide sunscreens weren’t far off and they had the added benefit of making you look like Ug in Salute Your Shorts. Thankfully, these physical blockers can now be added to sunscreen as nanoparticles. Ooh.

Then there are the chemical blockers, with names like Octyl Salicylate and Avobenzone. There are a lot of them, too, because no one compound blocks the entire UV spectrum. Which means that when you go about making your sunscreen, you need to bring all the chemicals.

Last week, after getting burned, I started using Sun Bum’s SPF 50. I liked it, even though it made me smell like a bottle of Malibu rum. But upon looking at the ingredients while researching this post, I discovered it’s exclusively a chemical blocker, which made me retroactively sad. Next time I’ll be sure to bring to big guns.

I bought SPF 50 at the time because I figured more is better. While sort of true, it’s trickier than that. In this informative Q&A on the FDA website, they explain there is “not sufficient data to show that products with SPF values higher than 50 provide greater protection for users than products with SPF values of 50.” According to the American Melanoma Foundation, this is mostly because SPF values are logarithmic in nature, wherein SPF 2 blocks 50% of UV light, SPF 15 blocks 93%, and SPF 34 blocks 97%. The FDA change in labeling is mostly to protect consumers from unrealistic claims.

Which explains why I couldn’t find any SPF 3000 for my paranoid skin.

Though my desire to have no errant photons touch my skin was justified when I learned that as it stands, most people are doing it wrong. Slather that stuff on, folks.

As with all things, there have been concerns raised over the toxicity of the sunscreen itself, but so far none of the risks have been deemed greater than unprotected exposure to UV radiation. The effects of titanium dioxide, zinc oxide nanoparticles, and oxybenzone are still being studied, and it’s important not to freak out quite yet. In the meantime, if you’re worried about the possible harmful effects of sunscreen, you’re better off sitting under an umbrella and skipping those tanning sessions.


This post was brought to you by Boy I Bet You Wish I Wrote This in May—Sorry


**PBS has a great article about how they work, and how they may not.