What's the Difference Between Sunscreen and Sunblock and Which One Should I Pick?

While trying to find a suitable SPF product, we're left confused by so many different labels - sunscreen or sunblock, chemical or physical sunscreen. So how are they different, and is the one better than the other?

September 11, 2021 5 minutes read

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Exposure to UV radiation influences the DNA in our skin, causing cells mutations and major damage. It speeds up the process of skin aging, often referred to as photoaging, and it's one of the main factors responsible for skin cancer. As a result, we're becoming more aware of the importance of protecting and pampering our skin and putting some effort into including sunscreen in our daily skincare routine.

But with supermarket and drugstore aisles stocked up with different types of products, we quickly start to wonder: Is there any difference between sunscreen and sunblock? And which one is better for me?

In this article, we'll explain the difference between the two and try to clarify the confusion.

But first, let's talk about the importance of sun protection and when you should be wearing it.

When Should I Wear Sun Protection?

The majority of us reach for sun protection only once the summer starts approaching. However, you should know that you need to protect your face, neck, ears, lips, and hands – basically everything that isn't covered with clothing – throughout the year.

This might come as a shock to you, but research shows that skin cancer rates in Idaho, Minnesota, and Utah are actually higher than those in southern states, such as California, Florida, and New Mexico. This is partly because many people neglect to wear sunscreen or sunblock during the winter months.

Even though you might not feel it, UV rays are equally as strong during colder seasons. They penetrate the clouds, plus the snow reflects up to 80% of the UV radiation; which is far more than sand, reflecting only about 25%. For this reason, wearing a cream or lotion with a high SPF is paramount throughout the year, including sunny and cloudy days in the summer and winter months.

Here are some general sun safety guidelines dermatologists recommend:

#1: Wear sun protection when the sun is the most intense, between 11 AM and 3 PM;

#2: Use it when you're spending time outside, regardless of the time of the day;

#3: Don't neglect to wear SPF when inside, especially if you're in a direct sun-line or close to a window;

#4: Use sunscreens or sunblocks with a high protection factor, at least 30;

#5: Reapply it every two hours when outside; or right after swimming;

#6: Make sure to apply enough of the product; for best protection, apply approximately half a teaspoon for the whole face, another half for the neck, and at least two teaspoons for each limb;

#7: Wear a wide-brimmed hat whenever possible, as well as protective clothing, sunglasses, and others;

#8: Remember to stay hydrated.

Now, when we covered the basics, we can go on and clarify the difference between the two types of sun protectants – sunscreens and sunblocks.

What's the Difference Between Sunscreen and Sunblock?

We often use the word sunscreen when talking about sun protection, but sunscreen and sunblock have different active ingredients and the key difference between them lies in the way they protect the skin against damaging UV rays.

Sunscreens, also called chemical sunscreens, absorb the UV rays like a sponge, convert them into heat and then dissipate them. On the other hand, sunblocks, also known as physical or mineral sunscreens, form a physical shield and, as their name suggests, they reflect the visible light and block the UV rays from penetrating our skin.

Generally, we use the more loose term sunscreen interchangeably to describe both physical and chemical UV protection products, while sunblock is solely used for physical sun protectants.

Sunscreen: Pros and Cons

Sunscreens usually contain organic chemical SPF filters, such as Oxybenzone, Octisalate, Avobenzone, Octocrylene, Octinoxate, and Homosalate.

Chemical sunscreens are usually lighter in texture and easier to apply. Our skin absorbs them quicker, and they don't leave a white cast, making them a preferred option for everyday protection around the city.

On the downside, some people can be sensitive to certain sunscreen ingredients and find them particularly irritating around the eyes. Besides, after prolonged sun exposure, they tend to break down and lose their potency, so you'll have to reapply your sunscreen more often.

It's also important to note that recent studies have shown that certain chemical compounds found in sunscreens aren't environmentally friendly. Oxybenzone and Octinoxate are suspected to damage and kill coral reefs. That's why these chemicals are prohibited in Hawaii, with the goal to preserve the marine ecosystem.

Sunblock: Pros and Cons

Sunblocks, or as everybody calls them, mineral sunscreens, usually contain non-organic mineral compounds, such as Zinc Oxide and Titanium Dioxide.

They act as a physical barrier that stands between our skin and the damaging UV rays. However, recent studies have shown that sunblocks do a little bit of both, reflecting but also absorbing the UV light at the same time.

So, to some extent, we have a double defense with sunblocks. Additionally, the active ingredients in sunblocks or mineral sunscreens are less irritating and are usually found in sun protectants for kids.

However, these are far from being ideal cosmetically since they are much thicker in texture than chemical sunscreens and often leave a white cast.

For this reasons, many brands are coming up with new formulas for mineral sunscreens, breaking the zinc or titanium down to nanoparticles, making them easier for our skin to absorb. This has also been a cause for a lot of discussion since it's suspected that these nanoparticles cause damage to the marine ecosystem and coral reefs.

The Verdict: Is Sunscreen or Sunblock Better?

One isn't better than the other because both sunscreens and sunblocks offer reliable protection against UV light. When determining which form of sun protectant is better for you, it's best to check out the ingredients list and see which will suit your skin better.

So, base your decision on your skin type, not the type of sun block. If you have sensitive skin, mineral and hypo-allergenic sunscreens might be an ideal solution for you. People with sensitive and dry skin can benefit from mineral sunscreens in a moisturizing form.

On the other hand, if you are someone with oily and acne-prone skin, look for sunscreens that are lighter in texture, such as gels or fluids.

And finally, before buying sunscreen or sunblock, read the labels and make sure that it covers a broad spectrum of UV rays and has a high protection factor, from 30 to 50.

SPF, UVA, UVB... What the Heck Does It Mean?

To be armed and ready when shopping for your next favorite SPF product, you should know about the most common terms that will help you better understand the labels and know what you're buying.

What Does UVA Mean?

UVA is a type of ultra-violet radiation with a relatively long wavelength and the ability to penetrate the skin more deeply. These rays break down the collagen within the deeper layers of the skin, cause DNA mutation, and free radical damage, resulting in photoaging, fine lines, wrinkles, and sagging skin, as well as certain types of skin cancer [source].

To remember it, you can think of the A, in UVA, as in Aging. It is also important to note that UVA rays can easily go through glass, which means you need to wear sun protection even when you're inside if you spend time close to a window.

What Does UVB Mean?

Unlike UVA, UVB rays have a shorter wavelength and are partly blocked by the atmosphere. Hence, these rays can't penetrate into the skin's deeper layers and only hit it superficially. These rays are the primary cause for redness and burning but also skin cancer. In this case, you could think of the B, in UVB, as in Burning.

What Does SPF Mean?

SPF is an abbreviation for Sun Protection Factor, and is most commonly followed by a number. This number determines the amount of protection measured in time from the UVB rays the sunscreen can offer.

So, for example, if your sunscreen has an SPF 30 and your skin takes about five minutes to burn without protection, the sunscreen will protect you thirty times longer, which would then be 150 minutes of protected sun exposure. Similarly, if you need five minutes to burn without sun protection and put on sunscreen with an SPF 15, it's supposed to protect you for about 75 minutes.

However, it would be best if you took this calculation with a grain of salt because SPF 15 covers about 95% of UVB rays, SPF 30 covers about 97%, and SPF 50 has up to 98% of protection. And since the difference is minimal, sunscreens with higher SPFs offer just a slightly better protection, and only if you apply a proper amount of the sunscreen to your skin (one shot glass should be enough for an average sized person's body).

Takeaway...

At the end of the day, it doesn't matter whether you'll go for sunscreen or sunblock as long as you apply it correctly, reapply it every two hours, and take other precautions to protect yourself. Additionally, many brands make sun protectants with a combination of chemical and mineral filters.

To get the right product for you, read the labels, go for a broad spectrum of protection, covering both UVA and UVB radiation, and target higher SPFs, from thirty onwards. Target sunblock in the form of a lotion, gel, or cream, and avoid sunscreen sprays or mists as these don't guarantee an even application.

And one final piece of advice – test the product before applying it to your whole face or body. You never know what you might be sensitive or allergic to. So, do a small patch test on the inner side of your arm, wait for 24 hours, and if you don't have any reaction or irritation, you'll know the product will be safe to use on a wider skin area.

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