What is Sunscreen?

What is Sunscreen?

woman applying sunblock onto arms and legs

Sunscreen is most commonly understood to be a topical skin care product that helps protect the skin from sunburns. SPF (sun protection factor) is usually how we know we won’t get sunburnt. But what is sunscreen actually? 

What makes a sunscreen different from a regular cream is the addition of “active ingredients” which have been tested by the FDA and Health Canada for their ability to either absorb or reflect UV (ultraviolet) radiation. UV radiation is the radiation we can’t see, but emits from the sun and is absorbed into our skin.

There are different kinds of UV radiation (UVA, UVB, and UVC). 

What makes them different is their wavelengths. Longer wavelengths (UVA - ultraviolet A) can penetrate deeper into the skin's dermis causing more permanent damage. While shorter wavelengths (UVB - ultraviolet B) only penetrate the epidermis and are responsible for sunburns. 

We like to remember this by thinking UVA (A) aging, UVB (B) burns. 

UVC (ultraviolet C) has the shortest wavelength and is absorbed by the stratosphere, it does not make it to the skin.  

uv radiation in the skin

Image from Miiko Skin Co Summer Zinc Cream Guidebook [Click here for free download]

There are just over a dozen “active” sunscreen ingredients in the market. 

Some active ingredients are designed to protect the skin from UVB radiation, and some are designed to protect against UVA radiation. Understanding the difference can help you choose the safest and most effective sun protection for you! 

Have you ever seen “Broad Spectrum Sunscreen” on a label? This is a product with active ingredients to protect against the broader spectrum of UV radiation. 

visible light and uv spectrum

To recap, sunscreen is a sunscreen because it has “active ingredients” that protect against UV radiation. There are different types of radiation and different types of “active ingredients” to protect against either UVA or UVB radiation. 

Now, let’s talk a little more about the different types of active ingredients in sunscreens. Some are chemical absorbers, and some are physical filters (mineral sunblocks). Which means some sunscreen ingredients absorb into the skin and absorb UV radiation, while others sit on top of the skin and reflect UV radiation. You may put sunscreen on and think you're fully protected, but there are some things that might help you understand what protection really is and where to find it. 

graphic image of chemical vs physical sunscreen from Miiko Safe Summer Skin Guidebook

Image from Miiko Skin Co Summer Zinc Cream Guidebook [Click here for free download]

Here is an image we developed at Miiko Skin Co to highlight the 8 most common active ingredients in sunscreen and what kind of UV radiation they protect against:

8 most common active ingredients in sunscreen

What is our take home message about sunscreen?

Chemical absorbers are the most common “active ingredients” used in commercial sunscreens because they are more appealing and convenient. They absorb quickly and can last longer on the skin. However, scientists are finding these ingredients can be dangerous for the marine environment and even humans. 

Sunscreens that are designed to absorb UVA radiation are engineered to penetrate the skin barrier easily. As a result, so many other “inactive ingredients” in sunscreen, and all skin care products we use that day (think deodorant), are being absorbed more readily into the body. 

So it isn’t just the sunscreen ingredient, but how it changes the skin’s chemistry in such a way that other ingredients can penetrate into the skin and into the bloodstream more easily. Many sunscreen chemicals can be measured in blood, breast milk, and urine samples.

To learn more about how to choose a good natural sunscreen check out this blog.

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