science of sunscreen

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With the official start to summer next week I’ve decided to devote the rest of my posts this week to sun products & safety. As a pale and blonde haired girl, I’ve had my fair (pun intended) share of sunburns, mole scares and lots of learning experiences. So today I’ve decided to share some sun safety basics, as well as some of the science behind sunscreen!

sunscreen types

There are essentially two types of sunscreen (chemically speaking) that can protect our skin from UV rays. The first is physical sunscreen, which is classified as any sunscreen that contains a metal compound, most commonly titanium dioxide, and zinc oxide. These compounds work by physically covering our skin in small particles that block/reflect the UV rays from penetrating and damaging our skin (hence the white color). Secondly is chemical sunscreen, which includes compounds that soak into our skin to protect cells and repair any damage that may happen. Chemical sunscreens often include compounds such as oxybenzone and avobenzone. In addition to these sunscreen types, it’s important to keep your skin protected with clothing, hats, and sunglasses.

sun protection factor (SPF)

According to the FDA, the definition of SPF is “a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin”. However, and the FDA notes this in their article, SPF values can be altered by a variety of factors. These factors can include; time of day, skin type, sunscreen brand, sunscreen ingredients, amount applied, time of application, etc.

  • The American Academy of Dermatology recommends using SPF 30 or higher
  • a shot glass’s worth of sunscreen is a good guideline for how much you should be applying to your body in one application

The next sunscreen basic is something I’m sure everyone has seen before, the term broad spectrum. Broad spectrum refers to the sunscreen’s ability to block both UVA and UVB rays. I’ve heard the following phrase so many times, and it’s a great way to remember the difference between the two UV rays.

UV-A = aging, these ultraviolet rays will cause skin damage and lead to aging issues such as dark spots, wrinkles and sagging

UV-B = burning, these ultraviolet rays are the ones that cause your skin to turn red, peel, and scar

sunscreen marketing

Just like every other cosmetic product, sunscreen marketers have a lot of tricks they follow.

  • A myth the Beauty Brains once busted, “cloud sunscreen” is not anything special, nor should you buy into it
  • the FDA does not allow sunscreens to be labeled as “waterproof” anymore and only certain ones can be labeled “water resistant”
  • “Sport” sunscreen is simple marketing
  • “Baby” sunscreen contains less harsh ingredients (typically only has physical sunscreen in it), and can actually be used by anyone and is great for those with sensitive skin

The most important things to look for in sunscreen is the SPF value (30+), the term broad spectrum, the active ingredients used, and it’s water resistance, or how long it lasts against sweat before you need to reapply.

sun safety tips

When I originally wrote this post more than half of it was me ranting about sun safety and giving a million tips. I decided to alter my post a bit and share some super helpful links for learning about sun safety instead. But first, I’ll quickly share the most important sun safety tips, in my opinion.

  • Wear sunscreen daily, especially on your face, neck, and chest. It is the easiest anti-aging prevention you can take
  • Everyone needs to wear sunscreen, skin cancer currently is the most common form of cancer in the country, and it’s not determined by your skin color/tone
  • See a dermatologist once a year to get your skin checked, it is our biggest organ and should be treated as such

The Skin Cancer Foundation

FDA guidelines and regulations for sunscreen use 

American Academy of Dermatology 

CDC sun safety guidelines

American Cancer Society 

I hope you enjoyed this post and that my sun safety tips weren’t too mom-like. Let me know if you have any question or comments below! and be safe this summer!

11 thoughts on “science of sunscreen

  1. Block Island Organics says:

    Great tips! Particularly like the advice to look for a “Broad Spectrum” sunscreen as many folks are unaware of this. It’s the only way to make sure you are getting UVB and UVA protection. Just check the label. Our suncare products are broad spectrum for example.

    Liked by 1 person

    • Paige DeGarmo says:

      Because there are so many broad spectrum sunscreens, that contain both physical and chemical ingredients, I would say that it might be a better use of your time and money to just use on of these. If you applied a chemical first you’d have to wait for that to absorb (~15 mins) then apply the physical and wait for that to dry. Thanks for asking!


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