Most of us have experienced getting a sunburn at least once in our lives, and you don’t even have to go to the beach to get one! From simply driving to work in your car on a hot day to going out for a quick jog, your skin needs protection from the sun. Yet with all the sunscreen options out there, how do you know which one is right for you?
Sunscreen: Decoding the Science of Protection
We’re all familiar with sunscreen and have some basic idea about what it is and what it’s used for, but unbeknownst to many of us, that little bottle of product sitting on your shelf is more than just a liquid sun shield.
What is sunscreen?
Also known as sunblock, sunscreen is a manufactured protective barrier in a bottle. The ingredients in sunscreen form a protective layer that reflects UV radiation before it can penetrate the skin.
What is UVR?
Ultraviolet radiation (UVR) is a type of invisible, non-ionizing radiation. In small doses, UVR can provide some health benefits, such as providing vitamin D. On the other hand, excessive exposure can lead to serious health risks, such as skin cancer.
The Different Classifications of Ultraviolet Radiation
Some of you may not realize that ultraviolet radiation is not all the same. According to the U.S. Center for Disease Control and Prevention, there are three primary types of ultraviolet radiation based on their wavelengths.
- Ultraviolet A (UVA) Radiation – The longest type of wavelengths at 315-400 nm (nanometers), and having approximately 95% of the sun’s UV rays. The ozone layer does not absorb ultraviolet A radiation, which is the type of radiation that penetrates the skin deeply, causing tanning but also skin aging. It can also cause sunburn.
- Ultraviolet B (UVB) Radiation – UVB radiation has medium wavelengths measuring about 280-315 nm. This type of radiation affects the cells on the topmost layer of the skin and causes delayed tanning and blistering.
- Ultraviolet C (UVC) Radiation – Ultraviolet C radiation has the shortest wavelength (100-280 nm), but the highest energy level amongst the three categories. While this type of UVR is completely absorbed by the ozone layer and atmosphere, individuals can still get exposed to artificial sources such as UVC lights, mercury lamps, and welding torches.
Exposure to UVC radiation can lead to serious health conditions such as severe burns, photokeratitis, premature aging, and skin cancer.
What is SPF?
Whenever you pick up a bottle of sunscreen, you’ll most likely see the letters “SPF” followed by a number on the label. SPF stands for Sun Protection Factor, and the number following it indicates the level of protection from the sun the product provides.
The Types of Sunscreen
Now that we know a little bit more about how sunscreen works, it may surprise you to find out that there are actually different kinds of sunscreen. Not all sunscreens are made the same, and the formulation that’s best for you can depend on your needs.
- Mineral Sunscreen – Mineral sunscreens, also referred to as physical or organic sunscreen, these types of sunscreen often have active ingredients like zinc oxide or titanium dioxide that protect the skin by reflecting UVR.
- Chemical Sunscreen – Chemical sunscreen on the other hand, provides protection by absorbing the UVR and preventing them from reaching the skin itself. Just as the name suggests, chemical sunscreen makes use of chemicals such as avobenzone, oxybenzone, and octinoxate.
| Pros | Cons | |
| Mineral Sunscreen | – Good for sensitive skin – Good for acne prone skin – Immediate protection – Generally recognized safe by the FDA | – Thicker consistency, resulting in slower application – Leaves white residue on the skin |
| Chemical Sunscreen | – Lightweight texture for easy application – No residue – Water-resistant formulations – Statistically performs better than mineral sunscreen | – May cause allergic reactions – Not immediately effective. Takes approximately 20 minutes from application for effectivity – Absorbs into skin |
The Truth About SPF Numbers
Imagine you are at the store holding two different bottles of sunscreen. One hand holds a bottle labelled “SPF 15” while the other holds a bottle labelled “SPF 50”, you’re probably thinking that the bottle with SPF 50 will be a better purchase because of the higher number, but it’s actually not that simple.
What do the numbers mean?
In an earlier section, we mentioned that the SPF numbers on sunscreen packaging indicate the level of protection it provides. Contrary to popular belief, that number actually indicates how well the product can protect you from UVR, but not how long one can safely be exposed to UVR.
| SPF Ratings | % of UV Rays Blocked |
| 2 | 50% |
| 4 | 75% |
| 10 | 90% |
| 15 | 93% |
| 30 | 97% |
| 50 | 98% |
| 100 | 99% |
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Does a higher SPF rating mean a better product?
Sunscreens with higher SPF ratings are often more expensive than those with lower SPF ratings, but the truth of the matter is that products higher than SPF 30 are only marginally better at providing protection (as seen in the table above).
What SPF should I choose?
While there are certain factors to consider when purchasing sunscreen, such as lifestyle and how much sun exposure one gets, the consensus when purchasing sunscreen is to choose a product that is at least SPF 30 with the label “broad spectrum”.
Why Does the “Broad Spectrum” Coverage Matter?
We established that manufacturers do not create all sunscreen products equally. Another factor to consider when getting yourself a good quality sunscreen is the coverage it provides.
If a sunscreen has a “broad spectrum” label, it means that it provides protection against both Ultraviolet A (UVA) and Ultraviolet B (UVB) light. These two types of ultraviolet rays are the primary causes of skin damage and skin cancer, respectively.
Sunscreen Facts and Fiction
Even though the use of sunscreen has become more common, there still persist misconceptions and misinformation about the product that can heavily skew people’s perception.
Fiction: All sunscreens are the same.
Fact: As mentioned in the previous section, sunscreens come with different SPF ratings, different coverage, and even use cases. While all sunscreens provide a level of protection against UVR, they can vary greatly depending on their formulation.
Fiction: Sunscreen fully prevents sun damage.
Fact: Whenever people use the analogy of “sunscreen acts like a shield against UV rays”, they aren’t lying. Shields provide protection but also take damage from being hit with weaponry, and this damage gradually weakens with every hit. When we take that concept and apply it to sunscreen, the UVR that hits the layer of sunscreen breaks it down over time. This is why it’s important to choose an SPF that fits your lifestyle.
Fiction: You don’t need to use sunscreen if the sun isn’t out.
Fact: According to an article by the Cleveland Clinic, the Skin Cancer Foundation recommends that individuals older than six months of age should apply sunscreen daily, regardless of the weather.
There exists a misconception that because it’s cloudy, the sun’s rays aren’t as harsh. The actuality is that even on cloudy days, approximately 80% of the UVR can break through and damage the skin.
Fiction: Clothes can protect your skin, so you don’t need to put on sunscreen.
Fact: While clothing can provide a “first line of defense” against UVR, the protection provided is questionable at best. Factors such as the color of the clothing, the material, and even the way it feels on your body can affect how well it protects your skin from UVR.
Fiction: The sunscreen in your makeup is enough.
Fact: The SPF contained in makeup, while usually rated SPF 30+, is not enough to protect your skin. This is primarily because the components in the makeup that compose sunscreen are heavily mixed with the ingredients of the makeup itself and affect its efficacy.
Fiction: Darker skin doesn’t get damaged by the sun and UVR.
Fact: As mentioned earlier, professionals highly recommend that all individuals older than six months of age apply sunscreen daily. This is regardless of age, skin color, environment, etc.
In relation to this fact, a concerning statistic is that the five-year survival rate of melanoma for people of color is 67-70%, a staggering 24%-25% less than the survival rate of caucasian people at 92-94%, according to the Melanoma Research Foundation.
Final Notes
Sunscreen use is commonly misunderstood, leading to misconceptions about its effectiveness and necessity.
Sunscreen is an essential product that forms a protective barrier against harmful ultraviolet radiation (UVR), which can lead to skin cancer and other health risks. UVR is categorized into three types: UVA, UVB, and UVC, each with different effects on the skin.
Manufacturers formulate sunscreens in two types: mineral, which reflects UVR using ingredients like zinc oxide, and chemical, which absorbs UVR with compounds such as avobenzone. The effectiveness of sunscreen is indicated by its Sun Protection Factor (SPF) rating, which highlights the product’s level of protection—though higher SPF numbers indicate only marginally better protection after SPF 30. Broad-spectrum labels denote protection against both UVA and UVB rays, crucial for skin health.
