Sunscreen: Friend or Foe?

Look at the skin on the back of your hand. Then look at the skin on your inner thighs. Which would you rather have on your face? Thought so.

This test should demonstrate that sunscreen is the most effective beauty tool that you have at your disposal. All the laser resurfacing and facelifts in the world can’t replace healthy skin. It’s a heck of a lot easier to prevent wrinkles than to repair them.

Okay! Now that I’ve convinced you to use sunscreen, have a nice week and I’ll see you on Monday.

Or you can check out the deets. The rest of this post covers how the sun causes skin damage, as well as how sunscreen works and how to buy it.  Learning the science behind beauty; it’s what this blog is all about.

How Sunlight Works

Obviously, sunlight is overall a very good thing. I’m definitely not here to trash the sun. However, specific components of the sun can be dangerous. Think of it as a really good-looking boy in a nice car – something awesome that might just kill you.

The sun emits radiation from the entire electromagnetic spectrum, including, of course, the visible spectrum. What we care about is the frequency of the waves, as shown in the following diagram: (1)

Frequency is speed; how long does it take a wave to repeat itself? You can see in the diagram how the frequency of the electromagnetic waves increases from left to right.
Waves with a higher frequency than visible light are dangerous (see next section). When people talk about the harmful effects of the sun, they’re talking about ultraviolet (UV) rays. Higher frequency waves can’t pass through the Earth’s atmosphere.

There are two kinds of UV rays (actually, more than that, but I’ll spare you): UVA and UVB. This is important to know when you’re choosing a sunscreen. Table I highlights the major differences between them:  (2)

Table I:  UVA and UVB Rays

UVA 95% of UV radiation Penetrates skin more deeply Causes tanning Less likely to cause skin cancer Lower frequency waves
UVB <5% of UV radiation Mostly affects epidermis Causes burning More likely to cause skin cancer Higher frequency waves

How Does the Sun Cause Skin Cancer?

High-frequency waves have a lot of energy, and that energy can do work, including making or breaking chemical bonds. Now, this happens all the time in your body; it’s what’s known as being alive. The problem is that it’s a numbers game. The more chemical bonds that are altered in your body increases the number of bonds that are altered in your DNA. The more your DNA molecules change, the more likely it is that some of those cells will become mutagens.  You get where I’m going here, right?  The more mutagens you have running around, the more likely it is that one will become a carcinogen.  And I think we can all agree that that would be bad.

It’s just like cigarettes. Yes, there are people with lung cancer who never smoked, and people who have smoked three packs a day for 50 years who are just fine (they look like sh*t, though). Whatever. The fact is that smoking greatly increases your chances of getting lung cancer (or any of a number of disgusting diseases) for exactly the same reasons that I described above. Think of UV rays as cigarettes for the skin.  It’s true that you could never use sunscreen and not develop any nasty side effects.  It’s just unlikely.

How Does the Sun Damage Your Skin?


With all due respect to the survivors out there, I have more fear of lip wrinkles than I do of cancer.  I blame it on the media.  Or maybe I’m just super shallow.  Anyhoo …

The outer layer of the skin contains a dark pigment called melanin which functions as natural protection against the sun. The more you’re in the sun, the more melanin your body produces, leading to age spots and uneven skin tone. (3)

UV rays also damage collagen, the main protein responsible for keeping skin firm. Now, proteins are degraded and resynthesized in the body on a daily basis, but the idea is that the amount of any given protein should remain roughly the same. For reasons not entirely understood, UV causes increased degradation and decreased synthesis of collagen. The absence of collagen under the skin causes the epidermis to sag and wrinkle, a phenomenon known as photoaging. Aging itself also causes loss of collagen, but not nearly at the rate that photoaging does. (4)

The good news is … now you can judge people who think that microwaves are bad for you, which is super fun. Oh, and there’s some more good news: Sunscreen!

How Sunscreen Works

Sunscreen usually works by absorbing the energy from UV waves and then releasing the energy at a lower frequency. Some sunscreens can also reflect or scatter UV rays.

Either way, sunscreen prevents UV rays from touching the skin, so yay. Also, UV rays do not change the chemical structure of sunscreen. Sunscreen continues to protect you for as long as it’s on the skin. (5)

How to Buy Sunscreen

I don’t see the point of listing the various ingredients of sunscreen as there’s no evidence that some are more or less effective than others. However, if you’d like to read about them, have at it. Here’s Wikipedia’s list.

(BTW, a search for “ingredients in sunscreen” and the like will bring back a long list of articles about how certain ingredients are unsafe or even cancerous.  This is because people are idiots.  The FDA and the Skin Cancer Foundation have an enormous interest in making sure that sunscreen protects people from skin cancer, and deep pockets to perform as many studies as they need to make sure they can endorse sunscreen products.  You can trust the data from those studies.  More generally, if you read anything that begins “Studies indicate that … ” or “Experts say that … “and lacks a citation, you should regard it as garbage. All that crap out there is exactly why I decided to write this blog!)

Moving on …

When buying sunscreen, keep in mind that measurements of the effectiveness of the sunscreen should be thought of as approximations only. Most sun damage is invisible and even the visible effects, such as wrinkles, can’t be measured precisely. Certainly, the FDA sets guidelines and ensures that sunscreen labels are truthful, it’s just that you can’t measure five minutes of sun damage the way you can measure the weight of butter. Make sense?

Here is the definitive guide, according to moi, on what to look for in a sunscreen:

  • SPF (Sun Protection Factor): SPF is supposedly a measure of the fraction of UV rays that reach the skin. However, this also depends on many other variables such as time of day, location, when the sunscreen was applied and so on. The only real value of this measurement is to pick out which sunscreen offers the most protection. Just buy the highest SPF there is. I mean, why wouldn’t you?
  • Broad-Spectrum: This means that the sunscreen protects against both UVA and UVB light (remember those?). This is the most important thing to look for on a sunscreen bottle! Always buy broad-spectrum sunscreen.
  • Water-resistant: As all sunscreens eventually wash off, the FDA does not allow the term “waterproof” on sunscreen. In order to be “water-resistant”, the sunscreen is in theory expected to be effective for 40 minutes while swimming and 80 minutes while sweating. (Sweating for 80 minutes is kind of gross, btw.) Always buy water-resistant sunscreen. (6)
  •  Buy a sunscreen you enjoy wearing: Because you’re going to be wearing this stuff all day, every day, RIGHT??? Most importantly, get something that feels good on your skin. You might also want additional items in your sunscreen, like tint or moisturizer or the ground up skulls of your enemies. If you can’t find something you like in your drugstore, hit Amazon. Putting on your daily sunscreen should feel like angel’s wings fluttering all over your body. At the very least, you shouldn’t hate putting it on.
  • Anti-aging: Please don’t waste your money on anti-aging sunscreen. At least not until my article on anti-aging products comes out. K?
  • More expensive doesn’t mean better: If you compare the ingredients of the brand name sunscreen to the generic sunscreen, they’re super likely to be exactly the same.
  • Don’t forget your lip balm: Ick, who wants wrinkly lips? Pony up for the balm.

How to Apply Sunscreen


  • Remember that no sunscreen can protect you completely. Your best protection is clothing and shade. Also wear a hat and UV-blocking sunglasses (you want to keep the skin under your eyes smooth and wrinkle-free, right? Plus, I hear hats are making a comeback.)
  • Apply sunscreen every single day, even if you’re not going out, even if it’s blizzarding, even if you’re locked in a cellar in a burka. (Okay, you can skip the sunscreen for that last one.) UV rays don’t care about clouds or glass, they’ll attack you even when you’re sitting innocently in your kitchen drinking coffee. Make it a habit to wake up, pee, wash your face, exfoliate and THEN PUT ON SUNSCREEN. If you like to hang out naked in front of windows, apply sunscreen to your whole body. Otherwise, just apply it to exposed areas.
  • Don’t forget your ears, lips, back of neck, hands, feet, back, hairline and parts of the head that don’t have hair.
  • Use enough to thoroughly cover exposed areas. According to the American Cancer Society, about 1 ounce of sunscreen should be used to cover the arms, legs, neck, and face of the average adult. Okay, that’s not super helpful; what’s an average adult and for that matter, what’s an ounce? Nothing against the ACS, but I’d stick with “thoroughly cover”.  (7)
  • Rub the sunscreen into your skin thoroughly.  Your skin will absorb it faster and your clothes will thank you.
  • Wait about 30 minutes after applying to go out into the sun. Again, according to the ACS, this is in order to allow the ingredients to “fully bind to the skin”. I don’t know exactly what that means, but if the ACS says to do it, I’ll do it.  (7)
  • Reapply your sunscreen every two hours. It’s important to remember that you need to reapply as much as you needed to apply it in the first place.
  • Reapply immediately after swimming, sweating or pole dancing.

Reference List

Okay, that’s it! Next week I’m planning on continuing my anti-aging campaign by talking about Retinol.  What is it?  Why all the hype?  Does it actually work and if so how and if not why do I spend half my paycheck on it?  Etc.

As always, please get in touch if you have questions, comments, requests or if you just want to say hey. I’d love to hear from you.

Air kisses! See you on Monday.

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