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Sunscreen 101: Understand and Decode Sunscreen Terms

Are you a skincare beginner trying to wrap your head around all the terminologies when it comes to understanding everything about sunscreen? We’re here to decode the jargon, the acronyms, the symbols on sunscreen labels to help you make informed decisions on what is best for your skin.


What does SPF stand for?

SPF stands for Sun Protection Factor and it is a measure of a sunscreen’s ability to protect your skin against ultraviolet B (UVB) rays, which are responsible for sunburn and skin damage. We’ll explain more about UVB rays further in this guide. The number that follows this acronym represents the amount of time you can stay in the sun before burning, compared to the amount of time it would take without any sunscreen. For example, if your skin takes 20 minutes to turn pink or darken without sun protection, using a sunscreen with SPF15 would provide 300 minutes of protection (15x20=300). This number increases as you use sunscreens with higher SPF.

Although this simple math calculation can help to estimate the duration of how long the SPF factor can last on the skin, it is important to understand that the intensity of the ultraviolet rays are the same based on different hours of the day. For example, the exposure of the skin to UVB rays in the morning at 9am for one hour is the same as the exposure of the skin to UVB rays at 1pm for 15 minutes. The SPF is not just about the amount of time that the skin is exposed to UV radiation, but rather the amount of time and the intensity (amount of exposure) of UVB rays that are penetrating the skin based on environmental factors and the impact these solar energy rays have on the skin.


What do the different levels of SPF mean?

In the past research has shown that an SPF of 100 only provides marginally higher levels of protection when compared to sunscreens with SPF of 50. However, there is a recent research that showed greater efficacy of SPF100+ sunscreen when compared to SPF50+. Although the results were intriguing, this research has a few limitations that could have affected the results of this trial and in the world of science, recommendations should be made based on data and not the result of one research study. It is important to remember that using a sunscreen with SPF100 does not mean that the sunscreen provides 100% of coverage or you can neglect the reapplication of sunscreen on the skin. Don’t let the SPF number trick you into providing you with a false sense of security. Regardless of what SPF sunscreen you choose to use, reapplying your sunscreen depending on your environmental exposure is important to ensure that your skin is fully protected.

  • SPF15: This level of SPF blocks approximately 93% of UVB rays. This is a good option for daily activities with brief periods of sun exposure.
  • SPF30: This level of SPF blocks approximately 97% of UVB rays. The American Academy of Dermatology recommends using sunscreen with SPF30 or higher for sufficient protection when spending extended periods of time outdoors.
  • SPF50: This level of SPF blocks approximately 98% of UVB rays.
  • SPF100: This level of SPF blocks approximately 99% of UVB rays.


What does PA+ mean?

PA+, decoded as Protection Grade of UVA is a Japanese measurement system used to indicate the level of protection a sunscreen provides against Ultraviolet A (UVA) rays, the type of rays that contribute to skin aging, wrinkles and other types of skin damage deeper in the skin layers. The symbol “+” that comes after PA indicates the hierarchy of protection. The more pluses, the higher the UVA protection. It is helpful to note that PA+ only measures the level of protection against UVA rays and not UVB rays. This is why it is important to make educated choices based on both SPF and PA ratings on the sunscreen. We will explain more about how UVA affects the skin further in this guide.

  • PA+: Very low level of UVA protection
  • PA++: Low level of UVA protection
  • PA+++: Average level of UVA protection
  • PA++++: High level of UVA protection


What is PPD in sunscreen terminology?

PPD stands for Persistent Pigment Darkening. It is indicated by the “+” symbol following the protection grade of UVA (PA). This method measures that amount of UVA radiation required to cause a persistent darkening of the skin. In simple terms, PPD measures the time it takes for the skin to tan when protected versus unprotected. For example, a PPD of 6 means that it takes 6 times longer for the skin to tan when compared to unprotected skin.

  • + : 2 to less than 4
  • ++: 4 to less than 8
  • +++: 8 to less than 16
  • ++++: 16 or higher


What is UVA?

UVA, deciphered as Ultraviolet A rays are a type of UV radiation with long wavelength ranging from 320 to 400 nanometers and is present more abundantly (~95%) in sunlight. They have better ability to penetrate deeper into the skin layers and are responsible for the aging effects of sun exposure such as wrinkles, fine lines and age spots. When UVA penetrates the skin, it is absorbed by molecules in the cells and the free radicals generated from these interactions can cause damage to DNA, membranes and cellular components such as collagen fibers and elastin, leading to signs of premature skin aging. UVA rays are also responsible for the tan that you get when exposed to tanning beds or sunlight. They trigger the melanocytes, which are cells that produce skin pigmentations known as melanin that give the skin a tanned appearance.


What is UVB?

UVB, deciphered as Ultraviolet B rays are a type of UV radiation with short wavelength ranging from 290 to 320 nanometer and is present about 5% in sunlight. The shorter wavelength means that this type of radiation tends to only penetrate the top layer of the outer layer of the skin known as the epidermis. In contrast to UVA, UVB radiation can damage and mutate the DNA by creating lesions on the helix structure of the DNA.


What is organic sunscreen?

Organic or chemical sunscreens use organic UV filters to absorb UV radiation. The term comes from the fact that this group of filters use carbon-based chemicals to absorb UV radiation and turn it into heat. With the advancement in technology, the new generation of organic filters are less absorbed into the bloodstream, more photostable and provide a higher range of protection than traditional organic filters. They are also less allergenic and irritating to sensitive skin


What is inorganic sunscreen?

Inorganic sunscreen or physical (mineral) sunscreen uses inorganic UV filters such as titanium dioxide and zinc oxide to deflect and scatter UV rays from the skin. Although physical sunscreen can provide an instant barrier between your skin and the sun's UV ray, it is still recommended that you give time for products to settle onto your skin before going out into the sun. Inorganic sunscreen also tends to create a white cast effect after application. A white cast is a white layer with a purplish or greyish hue that is usually the result of the deflection of sun rays caused by inorganic filters that remain on the skin’s surface.


What does broad spectrum mean in sunscreen terms?

This term refers to products that have the ability to protect your skin from UVA and UVB radiation. Depending on which country you are residing, the term broad-spectrum can be rated differently and it does not give a good understanding of how much UVA protection you are getting from the product of choice. It is definitely recommended to look into additional specific rankings for UVA protection to get a better understanding of the product in use.

Now that you’ve learned all about sunscreens, check out our Korean sunscreen collection to find the best sunscreen that your skin will love.



De Gruijl, FR. Photocarcinogenesis: UVA vs UVB. Methods Enzymol
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Rünger TM., Epe, B., Möller, K.. Processing of directly and indirectly ultraviolet-induced DNA damage in human cells. Recent Results Cancer Res. 1995;139:31-42. doi: 10.1007/978-3-642-78771-3_3.


Kohli, I., Nicholson, CL., Williams, JD., Lyons, AB., Seo, IS., Maitra, P., Tian, X., Atillasoy, E., Lim, HW., Hamzavi, IH. Greater efficacy of SPF 100+ sunscreen compared with SPF 50+ in sunburn prevention during 5 consecutive days of sunlight exposure: A randomized, double-blind clinical trial. J Am Acad Dermatol . 2020 Apr;82(4):869-877. doi: 10.1016/j.jaad.2019.09.018


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